Data conversions

lsst.cst model for data and format conversions

lsst.cst.conversions.data_id_to_str(data_id)

Converts a data identifier dictionary to a string. Will work on any dict and is not specific to the dataId format.

Parameters:

data_id (dict) – Data identifier dictionary.

Returns:

data_id_str – Data identifier string.

Return type:

str

lsst.cst.conversions.ids_to_str(data_ids)

Transform a numpy array of object identifiers (long integers) to a string of comma-separated values enclosed in parentheses. This is the format required for a WHERE … IN … statement in a TAP query.

Parameters:

data_ids (numpy.ndarray) – Array of object IDs (long int).

Returns:

result – String of comma-separated IDs, in parentheses.

Return type:

str

lsst.cst.conversions.nearest_patch_from_ra_dec(ra, dec)

Return nearest deepCoadd skymap patch, and its tract, for a given RA and Dec.

Parameters:

  • ra (np.float64) – Right ascension, in decimal degrees.

  • dec (np.float64) – Declination, in decimal degrees.

Returns:

nearest_patch – Numerical identifiers for the nearest patch (and its tract), and the distance (in degrees) between the patch center and the input coordinates.

Return type:

dict

lsst.cst.conversions.psf_size_at_pixel_xy(psf, bbox, xy)

Obtains the size of the PSF in an image at a given xy coordinate.

Parameters:

  • psf (lsst.meas.extensions.psfex.PsfexPsf or lsst.meas.algorithms.CoaddPsf) – PSF object from a calexp or deepCoadd respectively; use .getPsf().

  • bbox (lsst.geom.Box2I) – Bounding box for the calexp or deepCoadd; use .getBBox().

  • xy (tuple [int, int]) – Pixel coordinates x and y where PSF size is to be evaluated.

Returns:

psf_size – Size of the PSF in pixels; sigma and FWHM.

Return type:

dict