create_astrometric_catalog

stcal.tweakreg.astrometric_utils.create_astrometric_catalog(wcs, epoch, catalog='GAIADR3', output='ref_cat.ecsv', gaia_only=False, table_format='ascii.ecsv', num_sources=None)[source]

Create an astrometric catalog that covers the inputs’ field-of-view.

Parameters:

  • wcs (~astropy.wcs.WCS) – WCS object specified by the user as generated by resample.resample_utils.make_output_wcs. This will typically have the same plate-scale and orientation as the first member in the list of input images to make_output_wcs. Fortunately, for alignment, this doesn’t matter since no resampling of data will be performed.

  • epoch (float) – Reference epoch used to update the coordinates for proper motion (in decimal year).

  • catalog (str, optional) – Name of catalog to extract astrometric positions for sources in the input images’ field-of-view. Default: GAIADR3. Options available are documented on the catalog web page.

  • output (str, optional) – Filename to give to the astrometric catalog read in from the master catalog web service. If None, no file will be written out.

  • gaia_only (bool, optional) – Specify whether or not to only use sources from GAIA in output catalog

  • num_sources (int) – Maximum number of brightest/faintest sources to return in catalog. If num_sources is negative, return that number of the faintest sources. By default, all sources are returned.

Notes

This function will point to astrometric catalog web service defined through the use of the ASTROMETRIC_CATALOG_URL environment variable.

Returns:

ref_table – Astropy Table object of the catalog

Return type:

~astropy.table.Table