calc_astrometric_error

rubin_sim.phot_utils.calc_astrometric_error(mag, m5, fwhm_geom=0.7, nvisit=1, systematic_floor=10)

Calculate an expected astrometric error. Can be used to estimate this for general catalog purposes (use typical FWHM and n_visit=Number of visit). Or can be used for a single visit, use actual FWHM and n_visit=1.

Parameters:

mag: `float`

Magnitude of the source

m5: `float`

Point source five sigma limiting magnitude of the image (or typical depth per image).

fwhm_geom: `float`, optional

The geometric (physical) FWHM of the image, in arcseconds. Default 0.7.

nvisit: `int`, optional

The number of visits/measurement. Default 1. If this is >1, the random error contribution is reduced by sqrt(nvisits).

systematic_floor: `float`, optional

The systematic noise floor for the astrometric measurements, in mas. Default 10mas.

Returns:

astrom_errfloat

Astrometric error for a given SNR, in mas.