# Reference/API¶

## pysynphot.binning¶

Utilities related to wavelength bin calculations.

pysynphot.binning.calculate_bin_centers(edges)

Calculate the centers of wavelengths bins given their edges.

Parameters: edges (array_like) – Sequence of bin edges. Must be 1D and have at least two values. centers – Array of bin centers. Will be 1D and have one less value than edges. ndarray
pysynphot.binning.calculate_bin_edges(centers)

Calculate the edges of wavelength bins given the centers.

The algorithm calculates bin edges as the midpoints between bin centers and treats the first and last bins as symmetric about their centers.

Parameters: centers (array_like) – Sequence of bin centers. Must be 1D and have at least two values. edges – Array of bin edges. Will be 1D and have one more value than centers. ndarray
pysynphot.binning.calculate_bin_widths(edges)

Calculate the widths of wavelengths bins given their edges.

Parameters: edges (array_like) – Sequence of bin edges. Must be 1D and have at least two values. widths – Array of bin widths. Will be 1D and have one less value than edges. ndarray

## pysynphot.Cache¶

This module is a container for IO-intensive items that should be read in only once, and then re-used from memory.

This includes the reddening laws (pysynphot.locations.RedLaws) and some indices for the catalog model atlases (pysynphot.Cache.CATALOG_CACHE).

pysynphot.Cache.reset_catalog_cache()

Empty the CATALOG_CACHE global variable.

## pysynphot.catalog¶

This module is useful for working with catalog spectra such as Castelli-Kurucz Atlas, Kurucz Atlas, and Phoenix Models.

Spectra are constructed from basis spectra which are indexed for various combinations of effective temperature ($$T_{\mathrm{eff}}$$), metallicity ([M/H]), and log surface gravity ($$\log g$$). The user may specify any combination of $$T_{\mathrm{eff}}$$, [M/H], and $$\log g$$ so long as each parameter is within the range for that parameter defined by the catalog.

For example, the Castelli-Kurucz Atlas catalog contains spectra for effective temperatures between 3500 and 50000 K. In this case, no spectrum can be constructed for $$T_{\mathrm{eff}}$$ of 50001 K or 3499 K. The range of parameters available may vary from catalog to catalog.

More information on catalogs can be found in Appendix A: Catalogs and Spectral Atlases.

class pysynphot.catalog.Icat(catdir, Teff, metallicity, log_g)

This class constructs a model from the grid available in catalogs. Specifically, they are Castelli-Kurucz Atlas, Kurucz Atlas, and Phoenix Models.

Each grid contains a master file named “catalog.fits”, as defined by pysynphot.locations.CAT_TEMPLATE. The basis spectra are located at pysynphot.locations.KUR_TEMPLATE. You may inspect the data files in CRDS to see how they are formatted.

Parameters: catdir ({'ck04models', 'k93models', 'phoenix'}) – Name of directory holding the catalogs. Teff (float) – Effective temperature of model, in Kelvin. metallicity (float) – Metallicity of model. log_g (float) – Log surface gravity of model.
name

Short description of the spectrum.

Type: str
parameter_names

Names for model parameters. This is used for error reporting.

Type: list of str
warnings

To store warnings.

Type: dict
isAnalytic

This is always False.

Type: bool
waveunits, fluxunits

Catalog units for wavelength and flux.

Type: Units
wave, flux

Wavelength set and associated flux in catalog units.

Type: array_like
Raises: pysynphot.exceptions.ParameterOutOfBounds – Given parameter value is out of bounds.

Examples

>>> spec = S.Icat('k93models', 6440, 0, 4.3)


## pysynphot.exceptions¶

Custom exceptions for pysynphot to raise.

class pysynphot.exceptions.PysynphotError(msg)

Bases: Exception

Parent class for pysynphot exceptions.

Parameters: msg (str) – Error message.
class pysynphot.exceptions.TableFormatError(msg, rows=None)

Exception to do with table access.

Parameters: msg (str) – Error message. rows (list) – Rows with wrong values.
class pysynphot.exceptions.DuplicateWavelength(msg, rows=None)

Exception for duplicate wavelength values in table.

class pysynphot.exceptions.ZeroWavelength(msg, rows=None)

Exception for wavelength values containing zero.

class pysynphot.exceptions.UnsortedWavelength(msg, rows=None)

Exception for wavelength values not in ascending or descending order.

class pysynphot.exceptions.BadRow(msg, rows=None)

Exception for invalid row in table.

class pysynphot.exceptions.OverlapError(msg)

Exception to do with overlap checking.

class pysynphot.exceptions.PartialOverlap(msg)

Exception for partial overlap between two spectra.

class pysynphot.exceptions.DisjointError(msg)

Exception for no overlap between two spectra.

class pysynphot.exceptions.GraphtabError(msg)

Exception to do with graph table traversal.

class pysynphot.exceptions.UnusedKeyword(msg)

Exception for unused keyword in graph table lookup.

class pysynphot.exceptions.IncompleteObsmode(msg)

Exception for incomplete observation mode in graph table lookup.

class pysynphot.exceptions.AmbiguousObsmode(msg)

Exception for ambiguous observation mode in graph table lookup.

class pysynphot.exceptions.UndefinedBinset(msg)

Exception for undefined binset in bandpass or observation.

class pysynphot.exceptions.ExtrapolationNotAllowed(msg)

Exception for invalid extrapolation.

class pysynphot.exceptions.ParameterOutOfBounds(msg)

Exception for invalid parameter value in a catalog.

class pysynphot.exceptions.IncompatibleSources(msg)

Exception for operation on two incompatible spectra types.

## pysynphot.extinction¶

This module handles deprecated extinction models for backward compatibility with IRAF STSDAS SYNPHOT.

class pysynphot.extinction.DeprecatedExtinction(extval, redlaw)

This class handles deprecated extinction models from IRAF STSDAS SYNPHOT like a spectral element.

Parameters: extval (float) – Extinction in magnitude. redlaw ({'gal1', 'smc', 'lmc', 'xgal'}) – Reddening law (Gal1, Smc, Lmc, or Xgal).
name

Name of the extinction law.

Type: str
citation

The publication where this curve was obtained from.

Type: str
isAnalytic

This is always False.

Type: bool
warnings

To store warnings

Type: dict
binset

This is reserved to be used by ObsModeBandpass.

Type: None
waveunits

This is set to Angstrom at initialization.

Type: Units
wave, throughput

Wavelength set in waveunits and associated unitless extinction.

Type: array_like

Examples

>>> extinction = S.Extinction(0.3, 'gal1')

class pysynphot.extinction.Gal1(extval)

Deprecated Milky Way extinction curve (Seaton 1979).

Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes.
name

Name of the extinction law.

Type: str
citation

The publication where this curve was obtained from.

Type: str
transparencytable

This is the same as $$\mathrm{THRU}$$ defined in reddening().

Type: array_like
class pysynphot.extinction.Smc(extval)

Deprecated SMC extinction curve (Prevot et al. 1984).

Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes.
name

Name of the extinction law.

Type: str
citation

The publication where this curve was obtained from.

Type: str
transparencytable

This is the same as $$\mathrm{THRU}$$ defined in reddening().

Type: array_like
class pysynphot.extinction.Lmc(extval)

Deprecated LMC extinction curve (Howarth 1983).

Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes.
name

Name of the extinction law.

Type: str
citation

The publication where this curve was obtained from.

Type: str
transparencytable

This is the same as $$\mathrm{THRU}$$ defined in reddening().

Type: array_like
class pysynphot.extinction.Xgal(extval)

Deprecated Extra-galactic extinction curve (Calzetti et al. 1994).

Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes.
name

Name of the extinction law.

Type: str
citation

The publication where this curve was obtained from.

Type: str
transparencytable

This is the same as $$\mathrm{THRU}$$ defined in reddening().

Type: array_like

## pysynphot.locations¶

This module handles locations of data files.

Global Variables

• pysynphot.locations.rootdir - Root directory for TRDS/CRDS data files. By default, it is extracted from your PYSYN_CDBS environment variable.
• pysynphot.locations.specdir - Data directory for data files distributed with this software.
• pysynphot.locations.CAT_TEMPLATE and pysynphot.locations.KUR_TEMPLATE - String templates used for Icat to select spectra from catalogs.
• pysynphot.locations.VegaFile - Vega spectrum to use for vegamag calculations.
• pysynphot.locations.EXTDIR - Directory containing extinction curves.
• pysynphot.locations.RedLaws - Dictionary mapping reddening laws to data files or cached instances (see Cache).
• pysynphot.locations.wavecat - Data file for wavetable.
• pysynphot.locations.CONVERTDICT - Dictionary mapping IRAF-style directory shortcuts to actual paths.
pysynphot.locations.get_data_filename(filename)

Map filename to its actual path.

Parameters: filename (str) – Filename to search. path – Full path to the file in data directory. str
pysynphot.locations.get_latest_file(template, raise_error=False, err_msg='')

Find the filename that appears last in sorted order based on given template.

Parameters: template (str) – Search template in the form of path/pattern where pattern is acceptable by fnmatch. raise_error (bool, optional) – Raise an error when no files found. Otherwise, will issue warning only. err_msg (str) – Alternate message for when no files found. If not given, generic message is used. filename – Latest filename. str IOError – No files found.
pysynphot.locations.irafconvert(iraffilename)

Convert the IRAF file name to its Unix equivalent.

Input can be in directory$file or $directory/file format. If '' is not found in the input string, it is returned as-is. Parameters: iraffilename (str) – Filename in IRAF format. unixfilename – Filename in Unix format. str AttributeError – Input is not a string. ## pysynphot.obsbandpass¶ This module handle bandpass of observation modes. pysynphot.obsbandpass.ObsBandpass(obstring, graphtable=None, comptable=None, component_dict={}) Generate a bandpass object from observation mode. If the bandpass consists of multiple throughput files (e.g., “acs,hrc,f555w”), then ObsModeBandpass is returned. Otherwise, if it consists of a single throughput file (e.g., “johnson,v”), then TabularSpectralElement is returned. See Observation Mode and Appendix B: OBSMODE Keywords for more details. Parameters: obstring (str) – Observation mode. comptable, component_dict (graphtable,) – See ObservationMode. bp Examples >>> bp1 = S.ObsBandpass('acs,hrc,f555w') >>> bp2 = S.ObsBandpass('johnson,v')  class pysynphot.obsbandpass.ObsModeBandpass(ob) Bandpass instantiated from an obsmode string. Also see Observation Mode, Appendix B: OBSMODE Keywords, and Appendix C: TMG, TMC, and TMT Files. Parameters: ob (str) – Observation mode. obsmode, name Same as input ob. component1, component2 Components and sub-components that belong to the observation mode. Type: CompositeSpectralElement or SpectralElement isAnalytic This is always False. Type: bool warnings To store warnings, which are inherited from all inputs. If they have the same warning keyword, the one from most recently read component is used. Type: dict primary_area See Area for how this is set. Type: float binset This is set with bandWave(), as described in Reference Data. Type: array_like waveunits User unit inherited from inputs, where all inputs are required to have the same unit or an exception will be raised. Type: Units throughputunits This is only to inform user that throughput is unitless. Type: None wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like Raises: NotImplementedError – Inputs have different wavelength units. TypeError – Both input spectra must be bandpasses. pysynphot.exceptions.IncompatibleSources – Input spectra have different telescope areas defined. pixel_range(waverange, waveunits=None, round='round') Returns the number of wavelength bins within waverange. Note This calls pixel_range() with self.binset as the first argument. Parameters: round (waverange,) – See pixel_range(). waveunits (str, optional) – The units of the wavelengths given in waverange. If None (default), the wavelengths are assumed to be in the units of self.waveunits. num – Number of wavelength bins within waverange. int or float pysynphot.exceptions.UndefinedBinset – If self.binset is None. showfiles() thermback() Calculate thermal background count rate for self.obsmode. Calculation uses ThermalSpectrum() to extract thermal component source spectrum in photlam per square arcsec. Then this spectrum is integrated and multiplied by detector pixel scale and telescope collecting area to produce a count rate in count/s/pix. This unit is non-standard but used widely by STScI Exposure Time Calculator. Note Similar to IRAF STSDAS SYNPHOT thermback task. Returns: ans – Thermal background count rate. float NotImplementedError – Bandpass has no thermal information in graph table. wave_range(cenwave, npix, waveunits=None, round='round') Get the wavelength range covered by the given number of pixels centered on the given wavelength. Note This calls wave_range() with self.binset as the first argument. Parameters: npix, round (cenwave,) – See wave_range(). waveunits (str, optional) – Wavelength units of cenwave and the returned wavelength range. If None (default), the wavelengths are assumed to be in the units of self.waveunits. waverange – The range of wavelengths spanned by npix centered on cenwave. tuple of floats pysynphot.exceptions.UndefinedBinset – If self.binset is None. pysynphot.obsbandpass.pixel_range(bins, waverange, round='round') Returns the number of wavelength bins within waverange. Parameters: bins (ndarray) – Wavelengths of pixel centers. Must be in the same units as waverange. waverange (array_like) – A sequence containing the wavelength range of interest. Only the first and last elements are used. Assumed to be in increasing order. Must be in the same units as bins. round ({‘round’, ‘min’, ‘max’, None}, optional) – How to deal with pixels at the edges of the wavelength range. All of the options, except None, will return an integer number of pixels. Defaults to 'round'. 'round' - Wavelength ends that fall in the middle of a pixel are counted if more than half of the pixel is within waverange. Ends that fall in the center of a pixel are rounded up to the nearest pixel edge. 'min' - Only pixels wholly within waverange are counted. 'max' - End pixels that are within waverange by any margin are counted. None - The exact number of encompassed pixels, including fractional pixels, is returned. num – Number of wavelength bins within waverange. int or float ValueError – If round is not an allowed value. pysynphot.exceptions.OverlapError – If waverange exceeds the bounds of bins. pysynphot.obsbandpass.wave_range(bins, cenwave, npix, round='round') Get the wavelength range covered by the given number of pixels centered on the given wavelength. Parameters: bins (ndarray) – Wavelengths of pixel centers. Must be in the same units as cenwave. cenwave (float) – Central wavelength of range. Must be in the same units as bins. npix (int) – Number of pixels in range, centered on cenwave. round ({‘round’, ‘min’, ‘max’, None}, optional) – How to deal with pixels at the edges of the wavelength range. All of the options, except None, will return wavelength ends that correpsonds to pixel edges. Defaults to 'round'. 'round' - A wavelength range is returned such that the ends are pixel edges and the range spans exactly npix pixels. Ends that fall in the center of bins are rounded up to the nearest pixel edge. 'min' - The returned wavelength range is shrunk so that it includes an integer number of pixels and the ends fall on pixel edges. May not span exactly npix pixels. 'max' - The returned wavelength range is expanded so that it includes an integer number of pixels and the ends fall on pixel edges. May not span exactly npix pixels. None - An exact wavelength range is returned. The wavelength ends returned may not correspond to pixel edges, but will cover exactly npix pixels. waverange – The range of wavelengths spanned by npix centered on cenwave. tuple of floats ValueError – If round is not an allowed value. pysynphot.exceptions.OverlapError – If cenwave is not within bins, or the returned waverange would exceed the limits of bins. ## pysynphot.observationmode¶ This module handles observation modes that are defined in graph tables. Global Variables • pysynphot.observationmode.rootdir - Same as pysynphot.locations.rootdir. • pysynphot.observationmode.datadir - Same as pysynphot.locations.specdir. • pysynphot.observationmode.wavecat - Same as pysynphot.locations.wavecat. • pysynphot.observationmode.CLEAR - String to represent a clear filter in an observation mode, i.e., ‘clear’. class pysynphot.observationmode.BaseObservationMode(obsmode, method='HSTGraphTable', graphtable=None) Class that handles the graph table, common to both optical and thermal observation modes. Also see Appendix C: TMG, TMC, and TMT Files. Parameters: obsmode (str) – Observation mode. method ({'HSTGraphTable'}) – Not used. graphtable (str or None) – Graph table name. If None, it is taken from refs. pardict Stores parameterized keywords and their values. For example, aper#0.1 would result in {'aper':0.1}. Type: dict modes Individual keywords that make up the observation mode. This includes parameterized ones. Type: list of str gtname Graph table name. Type: str compnames, thcompnames Optical and thermal component names based on keyword look-ups. The look-up is done using GetComponentsFromGT(). Type: list of str primary_area See Area for how this is set. Type: float components, pixscale Reserved to be used by sub-classes. Type: None binset Filename containing the optimal wavelength set, or a string defining it. Type: str GetFileNames() Return throughput files of this observation mode. Returns: throughput_filenames list bandWave() Return the binned wavelength set most appropriate for the observation mode, as defined by pysynphot.locations.wavecat. Also see Reference Data. Returns: bandwave array_like showfiles() Like GetFileNames() but print the filenames instead. 'clear' components are not printed. Note Similar to IRAF STSDAS SYNPHOT showfiles task. class pysynphot.observationmode.ObservationMode(obsmode, method='HSTGraphTable', graphtable=None, comptable=None, component_dict={}) Class to handle optical observation mode. Parameters: method, graphtable (obsmode,) – See BaseObservationMode. comptable (str or None) – Component table name. If None, it is taken from refs. component_dict (dict) – Maps component filename to corresponding component object. pardict Stores parameterized keywords and their values. For example, aper#0.1 would result in {'aper':0.1}. Type: dict modes Individual keywords that make up the observation mode. This includes parameterized ones. Type: list of str gtname, ctname Graph and component table names. Type: str compnames, thcompnames Optical and thermal component names based on keyword look-ups. The look-up is done using GetComponentsFromGT(). Type: list of str primary_area See Area for how this is set. Type: float components List of component objects. Each object has throughput_name (str), throughput (SpectralElement), and waveunits (Units) attributes. Type: list pixscale Detector pixel scale, if applicable. Type: number or None binset Filename containing the optimal wavelength set, or a string defining it. Type: str Raises: IndexError – Component look-up failed. ThermalSpectrum() Calculate thermal spectrum. Returns: sp – Thermal spectrum in photlam. CompositeSourceSpectrum IndexError – Calculation failed. Throughput() Combined throughput from multiplying all the components together. Returns: throughput – Combined throughput. TabularSpectralElement or None ## pysynphot.observation¶ This module handles an observation and related calculations. class pysynphot.observation.Observation(spec, band, binset=None, force=None) Class to handle an observation. An observation is the end point of a chain of spectral manipulation. Most ObsBandpass objects have a built-in binset that is optimized for use with the specified observing mode (also see Wavelength Table). Specifying the binset here would override the built-in one. Parameters: spec (SourceSpectrum) – Source spectrum. band (SpectralElement) – Bandpass. binset (array_like or None) – Wavelength values to be used for binning when converting to counts. See initbinset(). force – See validate_overlap(). spectrum Same as input spec. bandpass Same as input band. binset Same as input binset. component1, component2 Components and sub-components that belong to the observation. operation This is always “multiply”. Type: str name Short description of the observation. Type: str warnings To store warnings, which are inherited from all inputs. If they have the same warning keyword, the one from most recently read component is used. Type: dict isAnalytic Flag to indicate whether this is an analytic spectrum. This is only True if both inputs are analytic. Type: bool primary_area Area of the telescope. This is inherited from either of the inputs, if available (not None). If inputs have different values, an exception is raised. Type: number or None waveunits, fluxunits User units inherited from source spectrum. Type: Units wave, flux Wavelength set and associated flux in user units. This is the native dataset. Type: array_like binwave, binflux Binned dataset. Type: array_like Raises: pysynphot.exceptions.IncompatibleSources – Input spectra have different telescope areas defined. as_spectrum(binned=True) Reduce the observation to a simple spectrum object. An observation is a complex object with some restrictions on its capabilities. At times, it would be useful to work with the simulated observation as a simple object that is easier to manipulate and takes up less memory. Parameters: binned (bool) – If True (default), export binned dataset. Otherwise, native. result – Observation dataset as a simple spectrum object. ArraySourceSpectrum countrate(binned=True, range=None, force=False) Calculate effective stimulus in count/s. Also see Count Rate and Effective Stimulus. Note This is the calculation performed when the ETC invokes countrate. Parameters: binned (bool) – If True (default), use binned data. Otherwise, use native data. range (tuple or None) – If not None, it must be a sequence with two floating-point elements specifying the wavelength range (inclusive) in the unit of self.waveunits in the form of (low, high); This is the range over which the integration will be performed. If the specified range does not exactly match a value in the wavelength set: If binned=True, the bin containing the range value will be used. This assumes self.binwave contains bin centers. If binned=False, native dataset will be interpolated to the specified values. (Not Implemented.) force (bool) – If False (default), partially overlapping ranges will raise an exception. If True, a partial overlap will return the calculated value instead. Disjoint ranges raise an exception regardless. ans – Count rate. float NotImplementedError – Wavelength range is defined for unbinned data. pysynphot.exceptions.DisjointError – Wavelength range does not overlap with observation. pysynphot.exceptions.PartialOverlap – Wavelength range only partially overlaps with observation. efflam(binned=True) Calculate effective wavelength of the observation. Calculation is done in the flux unit of flam. Note Similar to IRAF STSDAS SYNPHOT efflphot task. Parameters: binned (bool) – Use binned dataset for calculations. Otherwise, use native dataset. ans – Effective wavelength. float effstim(fluxunits='photlam') Compute effective stimulus. Calculations are done in given flux unit, and wavelengths in Angstrom. Native dataset is used. Parameters: fluxunits (str) – Flux unit. ans – Effective stimulus. float ValueError – Invalid integrated flux. initbinflux() Calculate binned flux and edges. Flux is computed by integrating the spectrum on the specified binned wavelength set, using information from the natural wavelength set. Native wave/flux arrays should be considered samples of a continuous function, but not their binned counterparts. Thus, it makes sense to interpolate (wave, flux) but not (binwave, binflux). Note Assumes that the wavelength values in the binned wavelength set are the centers of the bins. Uses pysynphot.pysynphot_utils.calcbinflux() C-extension, if available, for binned flux calculation. initbinset(binset=None) Set self.binwave. By default, wavelength values for binning are inherited from bandpass. If the bandpass has no binning information, then source spectrum wavelengths are used. However, if user provides values, then those are used without question. Parameters: binset (array_like or None) – Wavelength values to be used for binning when converting to counts. pivot(binned=True) Calculate pivot wavelength of the observation. Note This is the calculation performed when ETC invokes calcphot. Parameters: binned (bool) – Use binned dataset for calculations. Otherwise, use native dataset. ans – Pivot wavelength. float pixel_range(waverange, waveunits=None, round='round') Calculate the number of wavelength bins within given wavelength range. Note This calls pysynphot.obsbandpass.pixel_range() with self.binwave as the first argument. Parameters: round (waverange,) – See pysynphot.obsbandpass.pixel_range(). waveunits (str, optional) – The unit of the wavelength range. If None (default), the wavelengths are assumed to be in the units of self.waveunits. num – Number of wavelength bins within waverange. int or float pysynphot.exceptions.UndefinedBinset – No binned dataset. sample(swave, binned=True, fluxunits='counts') Sample the observation at the given wavelength. Also see Sampling. Parameters: swave (float) – Wavelength to sample. binned (bool) – Sample binned dataset (no interpolation). Otherwise, native (perform interpolation). fluxunits ({'counts'}) – Only the unit of counts is supported for now. ans – Sampled flux in given unit. float NotImplementedError – Flux unit is not supported or non-scalar wavelength is given. ValueError – Given wavelength out of range. validate_overlap(force) Validate that spectrum and bandpass overlap. Warnings are stored in self.warnings. Parameters: force ({‘extrap’, ‘taper’, None}) – If None, it is required that the spectrum and bandpass fully overlap. Partial overlap is allowed if this is set to 'extrap' or 'taper'. See validate_overlap(). wave_range(cenwave, npix, waveunits=None, round='round') Calculate the wavelength range covered by the given number of pixels, centered on the given wavelength. Note This calls pysynphot.obsbandpass.wave_range() with self.binwave as the first argument. Parameters: npix, round (cenwave,) – See pysynphot.obsbandpass.wave_range(). waveunits (str, optional) – Wavelength unit of the given and the returned wavelength values. If None (default), the wavelengths are assumed to be in the unit of self.waveunits. waverange – The range of wavelengths spanned by npix centered on cenwave. tuple of floats pysynphot.exceptions.UndefinedBinset – No binned dataset. writefits(fname, clobber=True, trimzero=True, binned=True, hkeys=None) Like pysynphot.spectrum.SourceSpectrum.writefits() but with binned=True as default. pysynphot.observation.check_overlap(a, b) Check for wavelength overlap between two spectra. Parameters: b (a,) – Typically a source spectrum, spectral element, observation, or bandpass from observation mode. result – Full, partial, or no overlap. {‘full’, ‘partial’, ‘none’} AttributeError – Given spectrum does not have flux or throughput. pysynphot.observation.validate_overlap(comp1, comp2, force) Validate the overlap between the wavelength sets of the two given components. Parameters: comp2 (comp1,) – Source spectrum and bandpass of an observation. force ({‘extrap’, ‘taper’, None}) – If not None, the components may be adjusted by extrapolation or tapering. comp1, comp2 – Same as inputs. However, comp1 might be tapered if that option is selected. warnings (dict) – Maps warning keyword to its description. KeyError – Invalid force. pysynphot.exceptions.DisjointError – No overlap detected when force is None. pysynphot.exceptions.PartialOverlap – Partial overlap detected when force is None. ## pysynphot.planck¶ This module handles Planck’s law of blackbody radiation. Global Variables • pysynphot.planck.H - Planck’s constant in CGS units. • pysynphot.planck.HS - Planck’s constant in SI units. • pysynphot.planck.C - Speed of light in SI units. • pysynphot.planck.K - Boltzmann constant in SI units. These are used in calculations to prevent floating point overflow, as defined in IRAF STSDAS SYNPHOT bbfunc task: • pysynphot.planck.LOWER • pysynphot.planck.UPPER These are constants used in llam_SI(): • pysynphot.planck.C1 - Power $$\times$$ unit area per steradian. • pysynphot.planck.C2 This is used in bb_photlam_arcsec(): • pysynphot.planck.F - Factor for conversion from $$\mathrm{m}^{2} \; \mathrm{sr}^{-1} \; \mathrm{m}^{-1}$$ to $$\mathrm{cm}^{2} \; \mathrm{arcsec}^{-2} \; \AA^{-1}$$. pysynphot.planck.bb_photlam_arcsec(wave, temperature) Evaluate Planck’s law in photlam per square arcsec. Note Uses llam_SI() for calculation, and then converts SI units back to CGS. Parameters: wave (array_like) – Wavelength values in Angstrom. temperature (float) – Blackbody temperature in Kelvin. result – Blackbody radiation in photlam per square arcsec. array_like pysynphot.planck.bbfunc(wave, temperature) Evaluate Planck’s law in photlam (per steradian). Note Adapted from IRAF STSDAS SYNPHOT bbfunc task. Parameters: wave (array_like) – Wavelength values in Angstrom. temperature (float) – Blackbody temperature in Kelvin. result – Blackbody radiation in photlam per steradian. array_like pysynphot.planck.llam_SI(wave, temperature) Like bbfunc() but in SI units. Note Adapted from SSP code by Dr. Anand Sivaramakrishnan in IRAF STSDAS SYNPHOT. Parameters: wave (array_like) – Wavelength values in meters. temperature (float) – Blackbody temperature in Kelvin. result – Blackbody radiation in SI units. array_like ## pysynphot.reddening¶ This module handles reddening laws and extinction calculations. pysynphot.reddening.print_red_laws() Print available extinction laws to screen. Available extinction laws are extracted from pysynphot.locations.EXTDIR. The printed names may be used with Extinction() to retrieve available reddening laws. Examples >>> S.reddening.print_red_laws() name reference -------- -------------------------------------------------------------- None Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 3.10. gal3 Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 3.10. lmc30dor Gordon et al. (2003, ApJ, 594, 279) R_V = 2.76. lmcavg Gordon et al. (2003, ApJ, 594, 279) R_V = 3.41. mwavg Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 3.10. mwdense Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 5.00. mwrv21 Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 2.1. mwrv4 Cardelli, Clayton, & Mathis (1989, ApJ, 345, 245) R_V = 4.0. smcbar Gordon et al. (2003, ApJ, 594, 279) R_V=2.74. xgalsb Calzetti et al. (2000. ApJ, 533, 682)  pysynphot.reddening.Extinction(extval, name=None) Generate extinction curve to be used with spectra. By default, reddening() is used to generate the extinction curve. If a deprecated reddening law is given, then DeprecatedExtinction is used instead. Note Reddening laws are cached in pysynphot.Cache.RedLaws for better performance. Repeated calls to the same reddening law here returns the cached result. Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes. name (str or None) – Name of reddening law (see print_red_laws()). If None (default), the average Milky Way extinction ('mwavg') will be used. ext – Extinction curve. ValueError – Invalid reddening law. Examples >>> ext = S.Extinction(0.3, 'mwavg')  class pysynphot.reddening.CustomRedLaw(wave=None, waveunits='InverseMicrons', Avscaled=None, name='Unknown Reddening Law', litref=None) Class to handle reddening law. Parameters: wave (array_like) – Wavelength values. waveunits (str) – Wavelength unit, as accepted by Units. By default, it is $$\mu m^{-1}$$. Avscaled (array_like) – Values of $$A(V)/E(B-V)$$. name (str) – Short description of the reddening law. litref (str) – Literature reference of the reddening law. wave, waveunits, name, litref Same as inputs. obscuration Same as input Avscaled. reddening(extval) Compute the reddening for the given extinction. \begin{align}\begin{aligned}A(V) = R(V) \; \times \; E(B-V)\\\mathrm{THRU} = 10^{-0.4 \; A(V)}\end{aligned}\end{align} Note self.litref is passed into ans.citation. Parameters: extval (float) – Value of $$E(B-V)$$ in magnitudes. ans – Extinction curve to apply to a source spectrum. ArraySpectralElement class pysynphot.reddening.RedLaw(filename) CustomRedLaw from a FITS file. Table must be in EXT 1 and contains the following columns: 1. WAVELENGTH 2. Av/E(B-V) Wavelength unit is extracted from TUNIT1 keyword in EXT 1 header. The primary header (EXT 0) must have SHORTNM and LITREF keywords. Parameters: filename (str) – FITS table filename. wave Wavelength values from the WAVELENGTH column in EXT 1. Type: array_like waveunits Value of TUNIT1 in EXT 1 header. Type: str name Value of SHORTNM in EXT 0 header. Type: str litref Value of LITREF in EXT 0 header. Type: str obscuration Values from the Av/E(B-V) column in EXT 1. ## pysynphot.refs¶ This module handles constants and look-up tables used in calculations. Global Variables • pysynphot.refs._default_waveset - Default wavelength set to use if no instrument-specific values found. • pysynphot.refs._default_waveset_str - Description of the default wavelength set above. • pysynphot.refs.PRIMARY_AREA - Telescope collecting area, i.e., the primary mirror, in $$\mathrm{cm}^{2}$$. The value for HST is 45238.93416. These are used in observationmode to look up throughput files for a given bandpass: • pysynphot.refs.GRAPHTABLE • pysynphot.refs.GRAPHDICT • pysynphot.refs.COMPTABLE • pysynphot.refs.COMPDICT • pysynphot.refs.THERMTABLE • pysynphot.refs.THERMDICT pysynphot.refs.getref() Current default values for graph and component tables, primary area, and wavelength set. Note Also see setref(). Returns: ans – Mapping of parameter names to their current values. dict pysynphot.refs.showref() Like getref() but print results to screen instead of returning a dictionary. pysynphot.refs.setref(graphtable=None, comptable=None, thermtable=None, area=None, waveset=None) Set default graph and component tables, primary area, and wavelength set. This is similar to setting refdata in IRAF STSDAS SYNPHOT. If all parameters set to None, they are reverted to software default. If any of the parameters are not None, they are set to desired values while the rest (if any) remain at current setting. Parameters: comptable, thermtable (graphtable,) – Graph, component, and thermal table names, respectively, for observationmode throughput look-up. Do not use “*” wildcard. area (float or None) – Telescope collecting area, i.e., the primary mirror, in $$\mathrm{cm}^{2}$$. waveset (tuple or None) – Parameters for set_default_waveset() as follow: (minwave, maxwave, num) - This assumes log scale. (minwave, maxwave, num, 'log') (minwave, maxwave, num, 'linear') ValueError – Invalid waveset parameters. pysynphot.refs.set_default_waveset(minwave=500, maxwave=26000, num=10000, delta=None, log=True) Set the default wavelength set, pysynphot.refs._default_waveset. Parameters: maxwave (minwave,) – The start (inclusive) and end (exclusive) points of the wavelength set. Values should be given in linear space regardless of log. num (int, optional) – The number of elements in the wavelength set. Only used if delta=None. delta (float, optional) – Delta between values in the wavelength set. If log=True, this defines wavelegth spacing in log space. log (bool, optional) – Determines whether the wavelength set is evenly spaced in log or linear space. ## pysynphot.renorm¶ This module handles normalization of source spectrum flux. pysynphot.renorm.DefineStdSpectraForUnits() Define StdSpectrum attribute for all the supported Flux Units. This is automatically done on module import. The attribute stores the source spectrum necessary for normalization in the corresponding flux unit. For photlam, photnu, flam, fnu, Jy, and mJy, the spectrum is flat in the respective units with flux value of 1. For counts and obmag, it is flat in the unit of counts with flux value of $$1 / N$$, where $$N$$ is the size of default wavelength set (see refs). For abmag and stmag, it is flat in the respective units with flux value of 0 mag. That is equivalent to $$3.63 \times 10^{-20}$$ fnu and $$3.63 \times 10^{-9}$$ flam, respectively. For vegamag, it is simply Vega. pysynphot.renorm.StdRenorm(spectrum, band, RNval, RNunitstring, force=False) This is used by SourceSpectrum for renormalization. Parameters: spectrum (SourceSpectrum) – Spectrum to renormalize. RNval, RNunitstring, force (band,) – See renorm(). newsp – Renormalized spectrum. CompositeSourceSpectrum ## pysynphot.spark¶ SPARK 0.6.1 is obtained from John Aycock (1998-2000). It is the underlying engine used by pysynphot.spparser. ## pysynphot.spectrum¶ This module contains the basis for all spectra classes, including source spectra and bandpasses. It also pre-loads the built-in Vega spectrum to pysynphot.spectrum.Vega. class pysynphot.spectrum.Integrator Integrator engine, which is the base class for SourceSpectrum and SpectralElement. trapezoidIntegration(x, y) Perform trapezoid integration. Parameters: x (array_like) – Wavelength set. y (array_like) – Integrand. For example, throughput or throughput multiplied by wavelength. sum – Integrated sum. float validate_fluxtable() Check for non-negative fluxes. If found, the negative flux values are set to zero, and a warning is printed to screen. This check is not done if flux unit is a magnitude because negative magnitude values are legal. validate_wavetable() Enforce monotonic, ascending wavelength array with no zero or negative values. Raises: pysynphot.exceptions.DuplicateWavelength – Wavelength array contains duplicate entries. pysynphot.exceptions.UnsortedWavelength – Wavelength array is not monotonic ascending or descending. pysynphot.exceptions.ZeroWavelength – Wavelength array has zero or negative value(s). class pysynphot.spectrum.SourceSpectrum This is the base class for all source spectra. addmag(magval) Add a scalar magnitude to existing flux values. $\mathrm{flux}_{\mathrm{new}} = 10^{-0.4 \; \mathrm{magval}} \; \mathrm{flux}$ Parameters: magval (number) – Magnitude value. sp – New source spectrum with adjusted flux values. CompositeSourceSpectrum TypeError – Magnitude value is not a scalar number. convert(targetunits) Set new user unit, for either wavelength or flux. This effectively converts the spectrum wavelength or flux to given unit. Note that actual data are always kept in internal units (Angstrom and photlam), and only converted to user units by getArrays() during actual computation. User units are stored in self.waveunits and self.fluxunits. Parameters: targetunits (str) – New unit name, as accepted by Units. flux Flux property. getArrays() Return wavelength and flux arrays in user units. Returns: wave (array_like) – Wavelength array in self.waveunits. flux (array_like) – Flux array in self.fluxunits. When necessary, self.primary_area is used for unit conversion. integrate(fluxunits='photlam') Integrate the flux in given unit. Integration is done using trapezoidIntegration() with x=wave and y=flux, where flux has been convert to given unit first. $\mathrm{result} = \int F_{\lambda} d\lambda$ Parameters: fluxunits (str) – Flux unit to integrate in. result – Integrated sum. Its unit should take account of the integration over wavelength. For example, if fluxunits='photlam' is given, then its unit is photon/s/cm^2. float redshift(z) Apply redshift to the spectrum. Redshifted spectrum is never analytic even if the input spectrum is. Output units are always Angstrom and PHOTLAM regardless of user units. Parameters: z (number) – Redshift value. copy – Redshifted spectrum. ArraySourceSpectrum renorm(RNval, RNUnits, band, force=False) Renormalize the spectrum to the specified value, unit, and bandpass. This wraps StdRenorm() for convenience. Basically, the spectrum is multiplied by a numeric factor so that the total integrated flux will be the given value in the given unit in the given bandpass. When force=False, if spectrum is not fully defined within the given bandpass, but the overlap is at least 99%, a warning is printed to screen and self.warnings['PartialRenorm'] is set to True. Parameters: RNval (number) – Flux value for renormalization. RNUnits (str) – Unit name, as accepted by Units, for RNval. band (SpectralElement) – Bandpass that RNval is based on. force (bool) – Force renormalization regardless of overlap status with given bandpass. If True, overlap check is skipped. Default is False. newsp – Renormalized spectrum. CompositeSourceSpectrum ValueError – Integrated flux is zero, negative, NaN, or infinite. pysynphot.exceptions.DisjointError – Spectrum and bandpass are disjoint. pysynphot.exceptions.OverlapError – Spectrum and bandpass do not fully overlap. sample(wave, interp=True) Sample the spectrum at given wavelength(s). This method has two behaviors: • When interp=True, wavelength(s) must be provided as a Numpy array. Interpolation is done in internal units (Angstrom and photlam). • When interp=False, wavelength must be a scalar number. The flux that corresponds to the closest matching wavelength value is returned. This option should only be used for sampling binned data in Observation. Parameters: wave (number or array_like) – Wavelength(s) to sample, given in user unit. interp (bool) – Allow flux interpolation. Default is True. ans – Sampled flux in user unit. number or array_like NotImplementedError – Non-scalar wavelength set provided when interpolation is not allowed. validate_units() Ensure that wavelenth and flux units belong to the correct classes. Raises: TypeError – Wavelength unit is not WaveUnits or flux unit is not FluxUnits. wave Wavelength property. writefits(filename, clobber=True, trimzero=True, binned=False, precision=None, hkeys=None) Write the spectrum to a FITS table. Primary header in EXT 0. FILENAME, ORIGIN, and any extra keyword(s) from hkeys will also be added. Table header and data are in EXT 1. The table has 2 columns, i.e., WAVELENGTH and FLUX. Data are stored in user units. Its header also will have these additional keywords: • EXPR - Description of the spectrum. • TDISP1 and TDISP2 - Columns display format, always “G15.7”. • GRFTABLE and CMPTABLE - Graph and component table names to use with associated observation mode. These are only added if applicable. If data is already double-precision but user explicitly set output precision to single, pysynphot.spectrum.syn_epsilon defines the allowed minimum wavelength separation. This limit ($$3.2 \times 10^{-4}$$) was taken from IRAF STSDAS SYNPHOT FAQ. Values equal or smaller than this limit are considered as the same, and duplicates are ignored, resulting in data loss. In the way that this comparison is coded, when such precision clash happens, even when no duplicates are detected, the last row is always omitted (also data loss). Therefore, it is not recommended for user to force single-precision when the data is in double-precision. Parameters: filename (str) – Output filename. clobber (bool) – Overwrite existing file. Default is True. trimzero (bool) – Trim off duplicate rows with flux values of zero from both ends of the spectrum. This keeps one row of zero-flux at each end, if it exists; However, it does not add a zero-flux row if it does not. Default is True. binned (bool) – Write self.binwave and self.binflux (binned) dataset, instead of self.wave and self.flux (native). Using this option when object does not have binned data will cause an exception to be raised. Default is False. precision ({‘s’, ‘d’, None}) – Write data out in single ('s') or double ('d') precision. Default is None, which will enforce native precision from self.flux. hkeys (dict) – Additional keyword(s) to be added to primary FITS header, in the format of {keyword:(value,comment)}. class pysynphot.spectrum.TabularSourceSpectrum(filename=None, fluxname=None, keepneg=False) Base class for ArraySourceSpectrum and FileSourceSpectrum. Parameters: filename (str or None) – File with spectral data (can be ASCII or FITS). If not None, data will be loaded from file at initialization. fluxname (str or None) – Column name containing flux data. This is only used if filename is given and is of FITS format. keepneg (bool) – Keep negative flux values instead of setting them to zero with a warning. Default is False. filename, name Same as input. warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like GetWaveSet() Return the wavelength set for the spectrum. Returns: waveset – Wavelength set (a copy of the internal wavelength table). array_like resample(resampledWaveTab) Resample the spectrum for the given wavelength set. Given wavelength array must be monotonically increasing or decreasing. Flux interpolation is done using numpy.interp(). Parameters: resampledWaveTab (array_like) – Wavelength set for resampling. resampled – Resampled spectrum. ArraySourceSpectrum taper() Taper the spectrum by adding zero flux to each end. This is similar to SpectralElement.taper(). There is no check to see if the spectrum is already tapered. Hence, calling this on a tapered spectrum will result in multiple zero-flux entries at both ends. The wavelengths to use for the new first and last points are calculated by using the same ratio as for the two interior points used at each end. Returns: OutSpec – Tapered spectrum. TabularSourceSpectrum class pysynphot.spectrum.ArraySourceSpectrum(wave=None, flux=None, waveunits='angstrom', fluxunits='photlam', name='UnnamedArraySpectrum', keepneg=False) Class to handle source spectrum from arrays. Parameters: flux (wave,) – Wavelength and flux arrays. fluxunits (waveunits,) – Wavelength and flux units, as accepted by Units. Defaults are Angstrom and photlam. name (str) – Description of the spectrum. Default is “UnnamedArraySpectrum”. keepneg (bool) – Keep negative flux values instead of setting them to zero with a warning. Default is False. name Same as input. warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like Raises: ValueError – Mismatched wavelength and flux arrays. class pysynphot.spectrum.FileSourceSpectrum(filename, fluxname=None, keepneg=False) Class to handle source spectrum loaded from ASCII or FITS table. Also see File I/O. Parameters: filename (str) – File with spectral data (can be ASCII or FITS). fluxname (str or None) – Column name containing flux data. This is only used if the given file is in FITS format. keepneg (bool) – Keep negative flux values instead of setting them to zero with a warning. Default is False. name Resolved filename; i.e., IRAF-style directory name is expanded to actual path name. Type: str fheader For FITS file, this contains headers from both extensions 0 and 1. If the extensions have the same keyword, the one from the latter is used. Type: dict warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like class pysynphot.spectrum.AnalyticSpectrum(waveunits='angstrom', fluxunits='photlam') Base class for analytic source spectrum. This includes BlackBody, FlatSpectrum, GaussianSource, and Powerlaw. Parameters: fluxunits (waveunits,) – Wavelength and flux units, as accepted by Units. Defaults are Angstrom and photlam. warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like GetWaveSet() Return the wavelength set for the spectrum. Returns: waveset – Wavelength set (a copy of the default wavelength table). array_like class pysynphot.spectrum.GaussianSource(flux, center, fwhm, waveunits='angstrom', fluxunits='flam') Class to handle a Gaussian source. Parameters: flux (float) – Total flux under the Gaussian curve, in given flux unit. center (float) – Central wavelength of the Gaussian curve, in given wavelength unit. fwhm (float) – FWHM of the Gaussian curve, in given wavelength unit. fluxunits (waveunits,) – Wavelength and flux units, as accepted by Units. Defaults are Angstrom and flam. total_flux Same as input flux. center, fwhm Same as inputs. sigma, factor These are $$\sigma$$ and $$A$$ as defined in Gaussian Emission. Type: float name Description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like GetWaveSet() Return the wavelength set that optimally samples the Gaussian curve. It has 101 values, as defined below: \begin{align}\begin{aligned}x_{\mathrm{first,last}} = x_{0} \; \pm \; 5 \; \sigma\\\delta x = 0.1 \; \sigma\end{aligned}\end{align} Returns: waveset – Wavelength set in internal unit. array_like class pysynphot.spectrum.FlatSpectrum(fluxdensity, waveunits='angstrom', fluxunits='photlam') Class to handle a flat source spectrum. Parameters: fluxdensity (float) – The constant flux value in the given flux unit. fluxunits (waveunits,) – Wavelength and flux units, as accepted by Units. Defaults are Angstrom and photlam. name Description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like redshift(z) Apply redshift to the flat spectrum. Unlike SourceSpectrum.redshift(), the redshifted spectrum remains an analytic flat source. Parameters: z (number) – Redshift value. ans FlatSpectrum class pysynphot.spectrum.Powerlaw(refwave, index, waveunits='angstrom', fluxunits='photlam') Class to handle a power-law source spectrum. Parameters: refwave (number) – Reference wavelength in the given unit. index (number) – Power-law index. fluxunits (waveunits,) – Wavelength and flux units, as accepted by Units. Defaults are Angstrom and photlam. name Description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like class pysynphot.spectrum.BlackBody(temperature) Class to handle a blackbody source. Flux is evaluated with bbfunc() and normalized with pysynphot.spectrum.RENORM, which is: $\mathrm{RENORM} = \pi \; (\frac{R_{\odot}}{1 \; \mathrm{kpc}})^{2}$ Parameters: temperature (number) – Blackbody temperature in Kelvin. temperature Same as input. name Description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool waveunits, fluxunits User units for wavelength and flux. Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like class pysynphot.spectrum.CompositeSourceSpectrum(source1, source2, operation) Class to handle composite spectrum involving source spectra. Parameters: source2 (source1,) – One or both of the inputs must be source spectrum. operation ({'add', 'multiply'}) – Math operation to perform. component1, component2 Same as input source1 and source2. operation Same as input. name Short description of the spectrum. Type: str warnings To store warnings, which are inherited from both input sources. If inputs have the same warning keyword, the one from source2 is used. Type: dict isAnalytic Flag to indicate whether this is an analytic spectrum. This is only True if both inputs are analytic. Type: bool primary_area Area of the telescope. This is inherited from either of the inputs, if available (not None). If inputs have different values, an exception is raised. Type: number or None waveunits, fluxunits User units inherited from source1 (if available) or source2 (if not). Type: Units wave, flux Wavelength set and associated flux in user units. Type: array_like Raises: pysynphot.exceptions.IncompatibleSources – Input spectra have different telescope areas defined. GetWaveSet() Obtain the wavelength set for the composite spectrum. This is done by using MergeWaveSets() to form a union of wavelength sets from its components. Returns: waveset – Composite wavelength set. array_like complist() Return a list of all components and sub-components. This is for use with __iter__(). tabulate() Return a simplified version of the spectrum. Composite spectrum can be overly complicated when it has too many components and sub-components. This method copies the following into a simple (tabulated) source spectrum: • Name • Wavelength array and unit • Flux array and unit Returns: sp – Tabulated source spectrum. ArraySourceSpectrum class pysynphot.spectrum.SpectralElement This is the base class for all bandpasses and spectral elements (e.g., filter and detector response curves). binset This is reserved to be used by ObsModeBandpass. Type: None GetThroughput() Obtain throughput for the spectrum. Returns: throughput – Throughput values. array_like GetWaveSet() Obtain the wavelength set for the spectrum. Returns: wave – Wavelength set in internal unit. array_like avgwave() Calculate Bandpass Average Wavelength. Returns: ans – Average wavelength. float check_overlap(other) Check overlap with another spectrum. Also see Overlap Checks. This checks whether the wavelength set of the given spectrum is defined everywhere within self. Wavelength values where throughput is zero are excluded from the check. Typical use case is for checking whether a source spectrum is fully defined over the range of a bandpass. This check is asymmetric in the sense that if self is fully defined within the given spectrum, but not the other way around, it will still only return “partial”. If the given spectrum is analytic, the result is always “full”. Example of full overlap: |---------- other ----------| |------ self ------|  Examples of partial overlap: |---------- self ----------| |------ other ------| |---- other ----| |---- self ----| |---- self ----| |---- other ----|  Examples of no overlap: |---- self ----| |---- other ----| |---- other ----| |---- self ----|  Parameters: other (SourceSpectrum or SpectralElement) – The other spectrum. ans – Overlap status. {‘full’, ‘partial’, ‘none’} check_sig(other) Check overlap insignificance with another spectrum. Also see Overlap Checks. Note Only use when check_overlap() returns “partial”. Parameters: other (SourceSpectrum or SpectralElement) – The other spectrum. ans – True means the lack of overlap is insignificant (i.e., okay to proceed). bool convert(targetunits) Set new user unit, for wavelength only. This effectively converts the spectrum wavelength to given unit. Note that actual data are always kept in internal unit (Angstrom), and only converted to user unit by GetWaveSet() during actual computation. User unit is stored in self.waveunits. Throughput is unitless and cannot be converted. Parameters: targetunits (str) – New unit name, as accepted by Units. efficiency() Calculate Bandpass Dimensionless Efficiency. Returns: ans – Bandpass dimensionless efficiency. float equivwidth() Calculate Bandpass Equivalent Width. This basically just calls integrate(). Returns: ans – Bandpass equivalent width. float integrate(wave=None) Integrate the throughput over the specified wavelength set. If no wavelength set is specified, the built-in one is used. Integration is done using trapezoidIntegration() with x=wave and y=throughput. Also see Bandpass Equivalent Width. Parameters: wave (array_like or None) – Wavelength set for integration. ans – Integrated sum. float photbw(floor=0) Calculate Bandpass RMS Band Width (SYNPHOT). Note For backward-compatibility with IRAF STSDAS SYNPHOT only. Parameters: floor (float) – Same as rmswidth(). ans – RMS band width (deprecated). float pivot(binned=False) Calculate Pivot Wavelength. Parameters: binned (bool) – This is reserved for use by Observation. If True, binned wavelength set is used. Default is False. ans – Pivot wavelength. float AttributeError – Binned wavelength set requested but not found. rectwidth() Calculate Bandpass Rectangular Width. Returns: ans – Bandpass rectangular width. float resample(resampledWaveTab) Resample the spectrum for the given wavelength set. Given wavelength array must be monotonically increasing or decreasing. Throughput interpolation is done using numpy.interp(). Parameters: resampledWaveTab (array_like) – Wavelength set for resampling. resampled – Resampled spectrum. ArraySpectralElement rmswidth(floor=0) Calculate Bandpass RMS Band Width (Koornneef). Parameters: floor (float) – Throughput values equal or below this threshold are not included in the calculation. By default (0), all points are included. ans – RMS band width. float sample(wave) Sample the spectrum. This uses resample() to do the actual computation. Parameters: wave (number or array_like) – Wavelength set for sampling, given in user unit. throughput – Sampled throughput. number or array_like taper() Taper the spectrum by adding zero throughput to each end. This is similar to TabularSourceSpectrum.taper(). There is no check to see if the spectrum is already tapered. Hence, calling this on a tapered spectrum will result in multiple zero-throughput entries at both ends. The wavelengths to use for the new first and last points are calculated by using the same ratio as for the two interior points used at each end. Returns: OutElement – Tapered spectrum. TabularSpectralElement throughput Throughput property. unit_response() Calculate Bandpass Unit Response. Warning Result is correct only if self.waveunits is in Angstrom. Returns: ans – Bandpass unit response. float validate_units() Ensure that wavelenth unit belongs to the correct class. There is no check for throughput because it is unitless. Raises: TypeError – Wavelength unit is not WaveUnits. wave Wavelength property. writefits(filename, clobber=True, trimzero=True, precision=None, hkeys=None) Write the spectrum to a FITS table. Primary header in EXT 0. FILENAME, ORIGIN, and any extra keyword(s) from hkeys will also be added. Table header and data are in EXT 1. The table has 2 columns, i.e., WAVELENGTH and THROUGHPUT. Wavelength data are stored in user unit. Its header also will have these additional keywords: • EXPR - Description of the spectrum. • TDISP1 and TDISP2 - Columns display format, always “G15.7”. • GRFTABLE and CMPTABLE - Graph and component table names to use with associated observation mode. These are only added if applicable. If data is already double-precision but user explicitly set output precision to single, pysynphot.spectrum.syn_epsilon defines the allowed minimum wavelength separation. This limit ($$3.2 \times 10^{-4}$$) was taken from IRAF STSDAS SYNPHOT FAQ. Values equal or smaller than this limit are considered as the same, and duplicates are ignored, resulting in data loss. In the way that this comparison is coded, when such precision clash happens, even when no duplicates are detected, the last row is always omitted (also data loss). Therefore, it is not recommended for user to force single-precision when the data is in double-precision. Parameters: filename (str) – Output filename. clobber (bool) – Overwrite existing file. Default is True. trimzero (bool) – Trim off duplicate rows with flux values of zero from both ends of the spectrum. This keeps one row of zero-flux at each end, if it exists; However, it does not add a zero-flux row if it does not. Default is True. precision ({‘s’, ‘d’, None}) – Write data out in single ('s') or double ('d') precision. Default is None, which will enforce native precision from self.throughput. hkeys (dict) – Additional keyword(s) to be added to primary FITS header, in the format of {keyword:(value,comment)}. class pysynphot.spectrum.TabularSpectralElement(fileName=None, thrucol='throughput') Base class for ArraySpectralElement and FileSpectralElement. Parameters: fileName (str or None) – File with spectral data (can be ASCII or FITS). If not None, data will be loaded from file at initialization. thrucol (str) – Column name containing throughput data. Default is “throughput” (case-insensitive). This is only used if filename is given and is of FITS format. name Same as input fileName. warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units throughputunits This is only to inform user that throughput is unitless. Type: {‘none’, None} wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like class pysynphot.spectrum.ArraySpectralElement(wave=None, throughput=None, waveunits='angstrom', name='UnnamedArrayBandpass') Class to handle bandpass from arrays. Parameters: throughput (wave,) – Wavelength and throughput arrays. waveunits (str) – Wavelength unit, as accepted by Units. Default is Angstrom. name (str) – Description of the spectrum. Default is “UnnamedArrayBandpass”. name Same as input. warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like Raises: ValueError – Mismatched wavelength and throughput arrays. class pysynphot.spectrum.FileSpectralElement(filename, thrucol=None) Class to handle bandpass loaded from ASCII or FITS table. Also see File I/O. Parameters: filename (str) – File with spectral data (can be ASCII or FITS). thrucol (str or None) – Column name containing throughput data. This is only used if the given file is in FITS format. name Resolved filename; i.e., IRAF-style directory name is expanded to actual path name. Type: str fheader For FITS file, this contains headers from both extensions 0 and 1. If the extensions have the same keyword, the one from the latter is used. Type: dict warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like class pysynphot.spectrum.InterpolatedSpectralElement(fileName, wavelength) Class to handle parameterized keyword in an observation mode. Parameters: fileName (str) – Filename followed by a column name specification between square brackets. For example: “mythru_syn.fits[fr388n#]” wavelength (number) – Desired value to interpolate to. This is not restricted to wavelength, but rather whatever parameter the file is parameterized for. name Expanded filename. Type: str interpval Same as input wavelength. warnings To store warnings. When extrapolation is not allowed but a default throughput column is present and used, warnings['DefaultThroughput'] is set to True. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units throughputunits This is only to inform user that throughput is unitless. Type: ‘none’ wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like Raises: Exception – File does not have columns needed for interpolation. pysynphot.exceptions.ExtrapolationNotAllowed – Extrapolation is not allowed and no default throughput column found. class pysynphot.spectrum.UniformTransmission(value, waveunits='angstrom') Class to handle a uniform bandpass. Parameters: value (number) – Constant throughput value for the bandpass. waveunits (str) – Wavelength unit, as accepted by Units. Default is Angstrom. value Same as input. name Short description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always True. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like GetWaveSet() Obtain wavelength set for the spectrum. Returns: waveset – Due to the nature of uniform transmission, this is always undefined. None wave waveset for uniform transmission. writefits(*args, **kwargs) Write to file using default waveset. class pysynphot.spectrum.Box(center, width, waveunits=None) Class to handle a box-shaped bandpass. Parameters: width (center,) – Center and width of the box in the given wavelength unit. waveunits (str or None) – Wavelength unit, as accepted by Units. If not given, assumed to be in Angstrom. name Description of the spectrum. Type: str warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like resample(resampledWaveTab) Resample the spectrum for the given wavelength set. Given wavelength array must be monotonically increasing or decreasing. Parameters: resampledWaveTab (array_like) – Wavelength set for resampling. resampled – Resampled spectrum. This is no longer a real Box spectrum. ArraySpectralElement sample(wavelength) Input wavelengths assumed to be in user unit. class pysynphot.spectrum.ThermalSpectralElement(fileName) Class to handle spectral element with thermal properties read from a FITS table. Note This class does not know how to apply itself to an existing beam. Its emissivity is handled by ThermalSpectrum(). Parameters: fileName (str) – Filename of the thermal emissivity table. name Same as input fileName. temperature Default temperature in Kelvin from header. Type: number beamFillFactor Beam filling factor from header. Type: number warnings To store warnings. Type: dict isAnalytic This is always False. Type: bool binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit for wavelength. Type: Units throughputunits This is only to inform user that throughput is unitless. Type: ‘none’ wave, throughput Wavelength set in user unit and associated unitless emissivity. Type: array_like class pysynphot.spectrum.CompositeSpectralElement(component1, component2) Class to handle composite spectrum involving bandpasses. Parameters: component2 (component1,) – Input bandpass. component1, component2 Same as inputs. name Short description of the spectrum. Type: str isAnalytic Flag to indicate whether this is an analytic spectrum. This is only True if both inputs are analytic. Type: bool warnings To store warnings, which are inherited from both input sources. If inputs have the same warning keyword, the one from component2 is used. Type: dict primary_area Area of the telescope. This is inherited from either of the inputs, if available (not None). If inputs have different values, an exception is raised. Type: number or None binset This is reserved to be used by ObsModeBandpass. Type: None waveunits User unit inherited from inputs, where both inputs are required to have the same unit or an exception will be raised. Type: Units throughputunits This is only to inform user that throughput is unitless. Type: None wave, throughput Wavelength set in user unit and associated unitless throughput. Type: array_like Raises: NotImplementedError – Inputs have different wavelength units. TypeError – Both input spectra must be bandpasses. pysynphot.exceptions.IncompatibleSources – Input spectra have different telescope areas defined. GetWaveSet() Obtain the wavelength set for the composite spectrum. This is done by using MergeWaveSets() to form a union of wavelength sets from its components. Returns: waveset – Composite wavelength set. array_like complist() Return a list of all components and sub-components. pysynphot.spectrum.MergeWaveSets(waveset1, waveset2) Return the union of the two wavelength sets. The union is computed using numpy.union1d, unless one or both of them is None. The merged result may sometimes contain numbers which are nearly equal but differ at levels as small as 1E-14. Having values this close together can cause problems due to effectively duplicate wavelength values. Therefore, wavelength values having differences smaller than or equal to pysynphot.spectrum.MERGETHRESH (defaults to 1E-12) are considered as the same. Parameters: waveset2 (waveset1,) – Wavelength sets to combine. MergedWaveSet – Merged wavelength set. It is None if both inputs are such. array_like or None pysynphot.spectrum.trimSpectrum(sp, minw, maxw) Create a new spectrum with trimmed upper and lower ranges. Parameters: sp (SourceSpectrum) – Spectrum to trim. maxw (minw,) – Lower and upper limits (inclusive) for the wavelength set in the trimmed spectrum. result – Trimmed spectrum. TabularSourceSpectrum ## pysynphot.spparser¶ This module implements the Language Parser. It uses pysynphot.spark. ## pysynphot.tables¶ This module handles graph and component tables. They are discussed in detail in Appendix C: TMG, TMC, and TMT Files. class pysynphot.tables.GraphTable(GFile=None) Class to handle a graph table. Parameters: GFile (str) – Graph table filename. keywords Values from KEYWORD column in EXT 1, converted to lowercase. Type: array_like innodes, outnodes, compnames, thcompnames Values from INNODE, OUTNODE, COMPNAME, and THCOMPNAME columns in EXT 1. Type: array_like primary_area Value from PRIMAREA in EXT 0 header, if exists. Type: number Raises: TypeError – No filename given. GetComponentsFromGT(modes, innode) Obtain components from graph table for the given observation mode keywords and starting node. Note This prints extra information to screen if pysynphot.tables.DEBUG is set to True. Parameters: modes (list of str) – List of individual keywords within the observation mode. innode (int) – Starting node, usually 1. components, thcomponents – List of optical and thermal component names. list of str KeyError – No matches found for one of the keywords. ValueError – Incomplete observation mode or unused keyword(s) detected. class pysynphot.tables.CompTable(CFile=None) Class to handle a component table. Parameters: CFile (str) – Component table filename. name Same as input CFile. compnames, filenames Values from COMPNAME and FILENAME columns in EXT 1. Type: array_like Raises: TypeError – No filename given. ## pysynphot.units¶ This module handles wavelength and flux units. Constants used for unit conversion are also defined here. pysynphot.units.Units(uname) Generate a unit object. Parameters: uname (str) – Wavelength or flux unit name. unit – Unit object. None means unitless. BaseUnit or None ValueError – Unknown unit name. class pysynphot.units.BaseUnit(uname) Base class for all units. Parameters: uname (str) – Unit name. name Same as input uname. Dispatch This is used by sub-classes for unit conversion by mapping target unit name to the relevant conversion method. Type: dict or None Convert(wave, flux, target_units) Perform unit conversion. Note This is only applicable to some of the available flux conversions. All other sub-classes must re-implement this method. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. target_units (str) – Unit to convert to. result – Converted values. number or array_like TypeError – Conversion to given unit is not allowed. class pysynphot.units.WaveUnits Base unit for wavelength. Since Angstrom is the internal unit used by pysynphot calculations, a wavelength unit can always convert to/from Angstrom. Conversion between two arbitrary units uses Angstrom as the intermediate unit. name To be set by sub-class of a specific wavelength unit. Type: None Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool Convert(wave, target_units) Perform unit conversion. Parameters: wave (number or array_like) – Wavelength values to be used for conversion. target_units (str) – Unit to convert to. result – Converted values. number or array_like TypeError – Conversion to given unit is not allowed. class pysynphot.units.Angstrom Class to handle Angstrom unit. Since Angstrom is the internal wavelength unit, it can convert to all the other supported units. name This is always ‘angstrom’. Type: str Dispatch Defines conversion to all supported wavelength units. Type: dict isFlux This is always False. Type: bool ToAngstrom(wave) Convert to Angstrom. Since there is no real conversion necessary, this returns a copy of input (if array) or just the input (if scalar). An input array is copied to avoid modifying the input in subsequent pysynphot processing. Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToCm(wave) Convert to cm. $\mathrm{cm} = 10^{-8} \; \AA$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToHz(wave) Convert to Hz. $\mathrm{Hz} = \frac{c}{\AA}$ where $$c$$ is as defined in Constants. Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToInverseMicron(wave) Convert to inverse micron. $\mu \mathrm{m}^{-1} = 10^{4} \; \AA^{-1}$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToMeter(wave) Convert to meter. $\mathrm{m} = 10^{-10} \; \AA$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToMicron(wave) Convert to micron. $\mu \mathrm{m} = 10^{-4} \; \AA$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToMm(wave) Convert to mm. $\mathrm{mm} = 10^{-7} \; \AA$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like ToNm(wave) Convert to nm. $\mathrm{nm} = 10^{-1} \; \AA$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like class pysynphot.units.Hz Class to handle Hz unit. name This is always ‘hz’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool ToAngstrom(wave) Convert to Angstrom. $\AA = \frac{c}{\mathrm{Hz}}$ where $$c$$ is as defined in Constants. Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like class pysynphot.units.InverseMicron Class to handle inverse micron unit. name This is always ‘1/um’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool ToAngstrom(wave) Convert to Angstrom. $\AA = \frac{10^{4}}{\mu \mathrm{m}^{-1}}$ Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like class pysynphot.units._MetricWavelength Class to handle meter unit and its prefixes. Note Angstrom is not a sub-class of this because as an internal unit, it requires special handling. name To be set by sub-class of a specific wavelength unit. Type: None Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool ToAngstrom(wave) Convert to Angstrom. Conversion is simply the input values multiplied by a factor specific to its sub-class. Parameters: wave (number or array_like) – Wavelength values to be used for conversion. result – Converted values. number or array_like class pysynphot.units.Nm Class to handle nm unit. name This is always ‘nm’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool factor Conversion factor. This is always 10. Type: float class pysynphot.units.Micron Class to handle micron unit. name This is always ‘micron’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool factor Conversion factor. This is always $$10^{4}$$. Type: float class pysynphot.units.Mm Class to handle mm unit. name This is always ‘mm’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool factor Conversion factor. This is always $$10^{7}$$. Type: float class pysynphot.units.Cm Class to handle cm unit. name This is always ‘cm’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool factor Conversion factor. This is always $$10^{8}$$. Type: float class pysynphot.units.Meter Class to handle meter unit. name This is always ‘m’. Type: str Dispatch Defines conversion to Angstrom. Type: dict isFlux This is always False. Type: bool factor Conversion factor. This is always $$10^{10}$$. Type: float class pysynphot.units.FluxUnits Base unit for flux. Since photlam is the internal unit used by pysynphot calculations, a flux unit can always convert to/from photlam. Conversion between two arbitrary units uses photlam as the intermediate unit. Note To support source spectrum renormalization without introducing circular import, all supported flux units must have their StdSpectrum attributes defined separately in DefineStdSpectraForUnits(). name To be set by sub-class of a specific flux unit. Type: None Dispatch Defines conversion to photlam. Type: dict isFlux This is always True. Type: bool isMag This is True if this is a magnitude. Type: bool isDensity This is True except for counts and obmag. Type: bool nativewave Native wavelength unit associated with the flux unit. This is for informational purpose only. Type: WaveUnits Convert(wave, flux, target_units, area=None) Perform unit conversion. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. target_units (str) – Unit to convert to. area (number or None) – Telescope area, if applicable. This is only needed for conversions involving counts or obmag. result – Converted values. number or array_like TypeError – Conversion to given unit is not allowed. class pysynphot.units.Photlam Class to handle photlam unit. Since photlam is the internal flux unit, it can convert to all the other supported units. $\mathrm{photlam} = \mathrm{photon} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \; \AA^{-1}$ name This is always ‘photlam’. Type: str Dispatch Defines conversion to all supported flux units. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits ToABMag(wave, flux, **kwargs) Convert to abmag. $\mathrm{AB}_{\nu} = -2.5 \; \log(h \lambda \; \mathrm{photlam}) - 48.6$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToCounts(wave, flux, area=None) Convert to counts. $\mathrm{counts} = \delta \lambda \; \times \; \mathrm{area} \; \times \; \mathrm{photlam}$ where $$\delta \lambda$$ represent bin widths derived from calculate_bin_edges() and calculate_bin_widths(), using the input wavelength values as bin centers. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. area (number or None) – Telescope collecting area. If not given, default value from Reference Data is used. result – Converted values. number or array_like ToFlam(wave, flux, **kwargs) Convert to flam. $\mathrm{flam} = \frac{hc}{\lambda} \; \mathrm{photlam}$ where $$h$$ and $$c$$ are as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToFnu(wave, flux, **kwargs) Convert to fnu. $\mathrm{fnu} = h \lambda \; \mathrm{photlam}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToJy(wave, flux, **kwargs) Convert to Jy. $\mathrm{Jy} = 10^{23} h \lambda \; \mathrm{photlam}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToOBMag(wave, flux, area=None) Convert to obmag. $\mathrm{obmag} = -2.5 \; \log(\delta \lambda \; \times \; \mathrm{area} \; \times \; \mathrm{photlam})$ where $$\delta \lambda$$ represent bin widths derived from calculate_bin_edges() and calculate_bin_widths(), using the input wavelength values as bin centers. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. area (number or None) – Telescope collecting area. If not given, default value from Reference Data is used. result – Converted values. number or array_like ToPhotlam(wave, flux, **kwargs) Convert to photlam. Since there is no real conversion necessary, this returns a copy of input flux (if array) or just the input (if scalar). An input array is copied to avoid modifying the input in subsequent pysynphot processing. Parameters: flux (wave,) – Wavelength (not used) and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToPhotnu(wave, flux, **kwargs) Convert to photnu. $\mathrm{photnu} = \frac{\lambda^{2}}{c} \; \mathrm{photlam}$ where $$c$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToSTMag(wave, flux, **kwargs) Convert to stmag. $\mathrm{ST}_{\lambda} = -2.5 \; \log(\frac{hc}{\lambda} \; \mathrm{photlam}) - 21.1$ where $$h$$ and $$c$$ are as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ToVegaMag(wave, flux, **kwargs) Convert to vegamag. $\mathrm{vegamag} = -2.5 \; \log(\frac{\mathrm{photlam}}{f_{\mathrm{Vega}}})$ where $$f_{\mathrm{Vega}}$$ is the flux of Vega resampled at given wavelength values and converted to photlam. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like TomJy(wave, flux, **kwargs) Convert to mJy. $\mathrm{mJy} = 10^{26} h \lambda \; \mathrm{photlam}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like TomuJy(wave, flux, **kwargs) Convert to $$\mu \mathrm{Jy}$$. $\mu \mathrm{Jy} = 10^{29} h \lambda \; \mathrm{photlam}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like TonJy(wave, flux, **kwargs) Convert to nJy. $\mathrm{nJy} = 10^{32} h \lambda \; \mathrm{photlam}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.Flam Class to handle flam unit. $\mathrm{flam} = \mathrm{erg} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \; \AA^{-1}$ name This is always ‘flam’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{\lambda}{hc} \; \mathrm{flam}$ where $$h$$ and $$c$$ are as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.Photnu Class to handle photnu unit. $\mathrm{photnu} = \mathrm{photon} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \; \mathrm{Hz}^{-1}$ name This is always ‘photnu’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{c}{\lambda^{2}} \; \mathrm{photnu}$ where $$c$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.Fnu Class to handle fnu unit. $\mathrm{fnu} = \mathrm{erg} \; \mathrm{s}^{-1} \mathrm{cm}^{-2} \mathrm{Hz}^{-1}$ name This is always ‘fnu’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{1}{h \lambda} \; \mathrm{fnu}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.Jy Class to handle Jy unit. $\mathrm{Jy} = 10^{-23} \; \mathrm{erg} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \mathrm{Hz}^{-1}$ name This is always ‘jy’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{10^{-23}}{h \lambda} \; \mathrm{Jy}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.mJy Class to handle mJy unit. $\mathrm{mJy} = 10^{-26} \; \mathrm{erg} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \mathrm{Hz}^{-1}$ name This is always ‘mjy’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{10^{-26}}{h \lambda} \; \mathrm{mJy}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.muJy Class to handle $$\mu \mathrm{Jy}$$ unit. $\mu \mathrm{Jy} = 10^{-29} \; \mathrm{erg} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \mathrm{Hz}^{-1}$ name This is always ‘mujy’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{10^{-29}}{h \lambda} \; \mu \mathrm{Jy}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.nJy Class to handle nJy unit. $\mathrm{nJy} = 10^{-32} \; \mathrm{erg} \; \mathrm{s}^{-1} \; \mathrm{cm}^{-2} \mathrm{Hz}^{-1}$ name This is always ‘njy’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isDensity This is always True. Type: bool isMag This is always False. Type: bool nativewave This is Hz by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = \frac{10^{-32}}{h \lambda} \; \mathrm{nJy}$ where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.Counts Class to handle counts unit. See Counts and Magnitudes for more details. name This is always ‘counts’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux This is always True. Type: bool isMag, isDensity This is always False. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits ToPhotlam(wave, flux, area=None) Convert to photlam. $\mathrm{photlam} = \frac{\mathrm{counts}}{\delta \lambda \; \times \; \mathrm{area}}$ where $$\delta \lambda$$ represent bin widths derived from calculate_bin_edges() and calculate_bin_widths(), using the input wavelength values as bin centers. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. area (number or None) – Telescope collecting area. If not given, default value from Reference Data is used. result – Converted values. number or array_like class pysynphot.units.LogFluxUnits Base class for magnitude, which often requires special handling. name, zeropoint To be set by sub-class of a specific magnitude unit. Type: None Dispatch Defines conversion to photlam. Type: dict isFlux, isMag This is always True. Type: bool isDensity This is True except for obmag. Type: bool nativewave Native wavelength unit associated with the flux unit. This is for informational purpose only. Type: WaveUnits linunit Corresponding linear flux unit to be set by sub-class. Type: None class pysynphot.units.ABMag Class to handle abmag unit. See Counts and Magnitudes for more details. name This is always ‘abmag’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isMag, isDensity This is always True. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits linunit Corresponding linear flux unit is Fnu. Type: FluxUnits zeropoint Its zero point is as defined by pysynphot.units.ABZERO. Type: float ToPhotlam(wave, flux, **kwargs) Convert to photlam. \begin{align}\begin{aligned}m = -0.4 \; (\mathrm{AB}_{\nu} + 48.6)\\\mathrm{photlam} = \frac{10^{m}}{h \lambda}\end{aligned}\end{align} where $$h$$ is as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.STMag Class to handle stmag unit. See Counts and Magnitudes for more details. name This is always ‘stmag’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isMag, isDensity This is always True. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits linunit Corresponding linear flux unit is Flam. Type: FluxUnits zeropoint Its zero point is as defined by pysynphot.units.STZERO. Type: float ToPhotlam(wave, flux, **kwargs) Convert to photlam. \begin{align}\begin{aligned}m = -0.4 \; (\mathrm{ST}_{\lambda} + 21.1)\\\mathrm{photlam} = \frac{10^{m} \lambda}{hc}\end{aligned}\end{align} where $$h$$ and $$c$$ are as defined in Constants. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like class pysynphot.units.OBMag Class to handle obmag unit. See Counts and Magnitudes for more details. name This is always ‘obmag’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isMag This is always True. Type: bool isDensity This is always False. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits linunit Corresponding linear flux unit is Counts. Type: FluxUnits zeropoint This is always 0. Type: float ToPhotlam(wave, flux, area=None) Convert to photlam. $\mathrm{photlam} = \frac{10^{-0.4 \; \mathrm{obmag}}}{\delta \lambda \; \times \; \mathrm{area}}$ where $$\delta \lambda$$ represent bin widths derived from calculate_bin_edges() and calculate_bin_widths(), using the input wavelength values as bin centers. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. area (number or None) – Telescope collecting area. If not given, default value from Reference Data is used. result – Converted values. number or array_like class pysynphot.units.VegaMag Class to handle vegamag unit. See Counts and Magnitudes for more details. name This is always ‘vegamag’. Type: str Dispatch Defines conversion to photlam. Type: dict isFlux, isMag, isDensity This is always True. Type: bool nativewave This is Angstrom by default. (Not used.) Type: WaveUnits linunit, zeropoint This is not used. Type: None vegaspec This is set to Vega. ToPhotlam(wave, flux, **kwargs) Convert to photlam. $\mathrm{photlam} = 10^{-0.4 \; \mathrm{vegamag}} \; f_{\mathrm{Vega}}$ where $$f_{\mathrm{Vega}}$$ is the flux of Vega resampled at given wavelength values and converted to photlam. Parameters: flux (wave,) – Wavelength and flux values to be used for conversion. kwargs (dict) – Extra keywords (not used). result – Converted values. number or array_like ## pysynphot.wavetable¶ This module handles selection of the appropriate wavelength table for a given observation mode. This is the same selection as used by ETC. Its wavecat_file (see below) can contain a mix of the following: • Name of the ASCII file containing the wavelength values. The filename can contain IRAF-style path shortcut. The file must only contain one column, with a single wavelength value in Angstrom in each row. The file can also contain comment lines that begin with “#”, which will be skipped. • A string of comma-separated coefficients that describe how to construct the wavelength table in Angstrom, in the format of (c0,c1[,c2[,c3]]), where c2 and c3 are optional. They are used for the following computation. Basically, the wavelength table runs from c0 to c1, with constant $$\delta \lambda$$ if c2 is undefined, or if c2 is given but not c3, or variable $$\delta \lambda$$ if both c2 and c3 are given: \begin{align}\begin{aligned}\begin{split}c_{2} = \left \{ \begin{array}{ll} c_{2} & : \mathrm{if given} \\ (c_{1} - c_{0})/1999 & : \mathrm{else, where 1999 was taken from IRAF STSDAS SYNPHOT} \end{array} \right.\end{split}\\\begin{split}c_{3} = \left \{ \begin{array}{ll} c_{3} & : \mathrm{if given} \\ c_{2} & : \mathrm{else} \end{array} \right.\end{split}\\n = \mathrm{int}(\frac{2 \; (c_{1} - c_{0})}{c_{3} + c_{2}}) + 1\\a = \frac{0.25 \; (c_{3}^{2} - c_{2}^{2})}{c_{1} - c_{0}}\\\lambda_{i=0,n-1} = (a i + c_{2}) i + c_{0}\end{aligned}\end{align} Example contents of a wavecat_file: # OBSMODE FILENAME_OR_COEFFS stis,e140h,c1598 (1497.0,1699.0,0.0066,0.0075) stis,g230l (1568.0,3184.0,1.6) stis,prism synphotdata/prism.dat
stis,prism,c1200    synphot$data/prism.dat  Global Variables • pysynphot.wavetable.wavecat_file - This is the same as pysynphot.locations.wavecat. It is the data file used in this module. • pysynphot.wavetable.wavetable - This is a Wavetable object created using pysynphot.wavetable.wavecat_file. class pysynphot.wavetable.Wavetable(fname) Class to handle wavelength table. __getitem__() is used to look up the wavelength table. It raises KeyError or ValueError if look-up fails. The look-up result is resolved into actual wavelength values by bandWave(). Parameters: fname (str) – Data file. file Same as input fname. lookup Look-up table using obsmode string as key. This is used by default for direct match. Type: dict setlookup Same as lookup but the obsmode string is converted into a frozen set consisting of its components. This is used for partial look-up if there is no direct match. Type: dict Raises: ValueError – Failed to parse input file. Examples >>> wavetab = S.wavetable.Wavetable(S.wavetable.wavecat_file) >>> wavetab['stis,g230l'] '(1568.0,3184.0,1.6)' >>> wavetab['stis,prism'] 'synphot$data/prism.dat'