JWSTSourceCatalog

class jwst.source_catalog.source_catalog.JWSTSourceCatalog(model, catalog, kernel_fwhm, aperture_params, abvega_offset, ci_star_thresholds)[source]

Bases: object

Class for the JWST source catalog.

Parameters:

modelImageModel: The input ImageModel. The data is assumed to be background-subtracted. Units are expected to be Jy.
catalogQTable: Source catalog table, e.g., as output from make_tweakreg_catalog().
kernel_fwhmfloat: The full-width at half-maximum (FWHM) of the 2D Gaussian kernel. This is needed to calculate the DAOFind sharpness and roundness properties (DAOFind uses a special kernel that sums to zero).
aperture_paramsdict: A dictionary containing the aperture parameters (radii, aperture corrections, and background annulus inner and outer radii).
abvega_offsetfloat: Offset to convert from AB to Vega magnitudes. The value represents m_AB - m_Vega.
ci_star_thresholdsarray-like of 2 floats: The concentration index thresholds for determining whether a source is a star. The first threshold corresponds to the concentration index calculated from the smallest and middle aperture radii (see aperture_params). The second threshold corresponds to the concentration index calculated from the middle and largest aperture radii. An object is considered extended if both concentration indices are greater than the corresponding thresholds, otherwise it is considered a star.

Notes

model.err is assumed to be the total error array corresponding to the input science model.data array. It is assumed to include all sources of error, including the Poisson error of the sources, and have the same shape and units as the science data array.

Attributes Summary

`aper_bkg_flux`	Return aperture local background fluxes (per pixel).
`aper_bkg_flux_err`	Return aperture local background flux errors (per pixel).
`aper_total_abmag`	Return the aperture-corrected total AB magnitude.
`aper_total_abmag_err`	Return the aperture-corrected total AB magnitude error.
`aper_total_flux`	Return the aperture-corrected total flux for sources.
`aper_total_flux_err`	Return the aperture-corrected total flux error for sources.
`aper_total_vegamag`	Return the aperture-corrected total Vega magnitude.
`aper_total_vegamag_err`	Return the aperture-corrected total Vega magnitude error.
`aperture_abmag_colnames`	Return the aperture AB magnitude column names.
`aperture_abmag_descriptions`	Return the aperture AB magnitude column descriptions.
`aperture_colnames`	Update the column_desc dictionary to include background flux information.
`aperture_flux_colnames`	Return the aperture flux column names.
`aperture_flux_descriptions`	Return the aperture flux column descriptions.
`aperture_vegamag_colnames`	Return the aperture Vega magnitude column names.
`aperture_vegamag_descriptions`	Return the aperture Vega magnitude column descriptions.
`catalog`	Build the final source catalog.
`ci_colname_descriptions`	Return the concentration indices column descriptions.
`ci_colnames`	Return the column names of the three concentration indices.
`colnames`	Return the column names in order for the final source catalog.
`concentration_indices`	Determine the concentration indices.
`extras_colnames`	Update the column_desc dictionary to include DAO starfinder computed quantities.
`is_extended`	Return a boolean indicating whether the source is extended.
`isophotal_abmag`	Return the isophotal AB magnitudes.
`isophotal_abmag_err`	Return the isophotal AB magnitude errors.
`isophotal_vegamag`	Return the isophotal Vega magnitudes.
`isophotal_vegamag_err`	Return the isophotal Vega magnitude errors.
`nn_dist`	Return the distance in pixels to the nearest neighbor for each source.
`nn_label`	Return the label number of the nearest neighbor for each source.
`roundness`	Compute the DAOFind source roundness statistic based on symmetry.
`segment_colnames`	Update the `column_desc` dictionary to include column names and descriptions.
`sharpness`	Compute the DAOFind source sharpness statistic.
`sky_centroid`	Compute the sky coordinate of the source centroid.
`sky_orientation`	Compute the orientation of the source major axis.
`xypos`	Return the (x, y) source centroids defined from the segmentation image.

Methods Summary

`convert_flux_to_abmag`(flux, flux_err)	Convert flux (and error) to AB magnitude (and error).
`convert_jy_to_mjysr`(model)	Convert data and errors from Jy to MJy/sr, and from `Quantity` to ndarray.
`convert_mjysr_to_jy`(model)	Convert data and errors from MJy/sr to Jy, and into `Quantity` objects.
`format_columns`(catalog)	Format the values in the output catalog.
`set_aperture_properties`()	Calculate the aperture photometry and set the values as dynamic attributes.
`set_ci_properties`()	Set the concentration indices as dynamic attributes.
`set_segment_properties`()	Calculate the segment-based source photometry and morphologies.

Attributes Documentation

aper_bkg_flux

Return aperture local background fluxes (per pixel).

Returns:

Quantity: The aperture local background fluxes.

aper_bkg_flux_err

Return aperture local background flux errors (per pixel).

Returns:

Quantity: The aperture local background flux errors.

aper_total_abmag

Return the aperture-corrected total AB magnitude.

Should be used only for unresolved sources.

Returns:

ndarray: The aperture-corrected total AB magnitude.

aper_total_abmag_err

Return the aperture-corrected total AB magnitude error.

Should be used only for unresolved sources.

Returns:

ndarray: The aperture-corrected total AB magnitude error.

aper_total_flux

Return the aperture-corrected total flux for sources.

Computed based on the flux in largest aperture. Should be used only for unresolved sources.

Returns:

Quantity: The aperture-corrected total flux

aper_total_flux_err

Return the aperture-corrected total flux error for sources.

Computed based on the flux in largest aperture. Should be used only for unresolved sources.

Returns:

Quantity: The aperture-corrected total flux error

aper_total_vegamag

Return the aperture-corrected total Vega magnitude.

Should be used only for unresolved sources.

Returns:

ndarray: The aperture-corrected total Vega magnitude.

aper_total_vegamag_err

Return the aperture-corrected total Vega magnitude error.

Should be used only for unresolved sources.

Returns:

ndarray: The aperture-corrected total Vega magnitude error.

aperture_abmag_colnames

Return the aperture AB magnitude column names.

Returns:

list of str: The aperture AB magnitude column names.

aperture_abmag_descriptions

Return the aperture AB magnitude column descriptions.

Returns:

list of str: The aperture AB magnitude column descriptions.

aperture_colnames

Update the column_desc dictionary to include background flux information.

Returns:

colnameslist of str: A list of the column names that were updated by this function.

aperture_flux_colnames

Return the aperture flux column names.

Returns:

list of str: The aperture flux column names.

aperture_flux_descriptions

Return the aperture flux column descriptions.

Returns:

list of str: The aperture flux column descriptions.

aperture_vegamag_colnames

Return the aperture Vega magnitude column names.

Returns:

list of str: The aperture Vega magnitude column names.

aperture_vegamag_descriptions

Return the aperture Vega magnitude column descriptions.

Returns:

list of str: The aperture Vega magnitude column descriptions.

catalog

Build the final source catalog.

Returns:

catalogTable: The final source catalog.

ci_colname_descriptions

Return the concentration indices column descriptions.

Returns:

list of str: The concentration indices column descriptions.

ci_colnames

Return the column names of the three concentration indices.

Returns:

list of str: The concentration indices column names.

colnames

Return the column names in order for the final source catalog.

Returns:

list of str: The column names.

concentration_indices

Determine the concentration indices.

These are calculated as the flux ratios of:

the middle / smallest aperture radii/EE, e.g., CI_50_30 = aper50_flux / aper30_flux
the largest / middle aperture radii/EE, e.g., CI_70_50 = aper70_flux / aper50_flux
the largest / smallest aperture radii/EE, e.g., CI_70_30 = aper70_flux / aper30_flux

Returns:

list of float: The concentration indices.

extras_colnames

Update the column_desc dictionary to include DAO starfinder computed quantities.

Returns:

colnameslist of str: A list of the column names that were updated by this function.

is_extended

Return a boolean indicating whether the source is extended.

Returns:

ndarray: A boolean array where True values denote extended sources.

isophotal_abmag

Return the isophotal AB magnitudes.

Returns:

ndarray: The isophotal AB magnitudes.

isophotal_abmag_err

Return the isophotal AB magnitude errors.

Returns:

ndarray: The isophotal AB magnitudes.

isophotal_vegamag

Return the isophotal Vega magnitudes.

Returns:

ndarray: The isophotal Vega magnitudes.

isophotal_vegamag_err

Return the isophotal Vega magnitude errors.

Returns:

ndarray: The isophotal Vega magnitude errors.

nn_dist

Return the distance in pixels to the nearest neighbor for each source.

Returns NaN if there is only one detected source or for non-finite xypos.

Returns:

Quantity: The distances in pixels to the nearest neighbors.

nn_label

Return the label number of the nearest neighbor for each source.

A label value of -1 is returned if there is only one detected source and for sources with a non-finite xcentroid or ycentroid.

Returns:

ndarray: The label number of the nearest neighbor.

roundness

Compute the DAOFind source roundness statistic based on symmetry.

The roundness characteristic computes the ratio of a measure of the bilateral symmetry of the object to a measure of the four-fold symmetry of the object.

“Round” objects have a roundness close to 0, generally between -1 and 1.

Returns:

ndarray: The DAOFind source roundness statistic.

segment_colnames

Update the column_desc dictionary to include column names and descriptions.

Returns:

colnameslist of str: A list of the column names that were updated by this function.

sharpness

Compute the DAOFind source sharpness statistic.

The sharpness statistic measures the ratio of the difference between the height of the central pixel and the mean of the surrounding non-bad pixels to the height of the best fitting Gaussian function at that point.

Stars generally have a sharpness between 0.2 and 1.0.

Returns:

ndarray: The DAOFind source sharpness statistic.

sky_centroid

Compute the sky coordinate of the source centroid.

The output coordinate frame is the same as the input wcs.

Returns:

SkyCoord or None: The sky coordinate of the source centroid, or None if the WCS is not set.

sky_orientation

Compute the orientation of the source major axis.

Returns:

Quantity: The position angle of the source major axis, measured East of North.

xypos

Return the (x, y) source centroids defined from the segmentation image.

Returns:

xyposndarray: A 2D array of the (x, y) source positions.

Methods Documentation

static convert_flux_to_abmag(flux, flux_err)[source]

Convert flux (and error) to AB magnitude (and error).

Parameters:

flux, flux_errQuantity: The input flux and error arrays in units of Jy.

Returns:

abmag, abmag_errndarray: The output AB magnitude and error arrays.

static convert_jy_to_mjysr(model)[source]: Convert data and errors from Jy to MJy/sr, and from Quantity to ndarray.

static convert_mjysr_to_jy(model)[source]: Convert data and errors from MJy/sr to Jy, and into Quantity objects.

static format_columns(catalog)[source]

Format the values in the output catalog.

Parameters:

catalogTable: The catalog to format.

Returns:

resultTable: The formatted catalog.

set_aperture_properties()[source]: Calculate the aperture photometry and set the values as dynamic attributes.

set_ci_properties()[source]: Set the concentration indices as dynamic attributes.

set_segment_properties()[source]

Calculate the segment-based source photometry and morphologies.

The values are set as dynamic attributes.