This is a photometric zeropoint server, using cataloged magnitudes from SDSS, USNOB1, APASS and 2-MASS to either lookup or calculate the SEDs for sources detected in an image, then using their cataloged/calculated magnitudes in a passband to calculate an estimate of the photometric zeropoint for a set of instrumental magnitudes. (E.G. SExtractor output.)
The main zeropoint.py script assumes that input files are readable with numpy.loadtxt --- i.e. #-commented, tab-or-space-delimited, and uniform. The first column should be RA, the second DEC, the third the instrumental mag, and the rest are arbitrary and unused.
REQUIRES commmand line tools findsdss8, find2mass, findusnob1. These should be available from http://cdsarc.u-strasbg.fr/doc/cdsclient.html
It was developed as part of my graduate work at UC Berkeley and is here released for anyone to use under the MIT licence.
Isaac Shivvers
To calculate the zeropoint for a field of y-band instrumental magnitudes (in the properly-formatted file `00146952_z_DECam.16.p.w.txt'):
python zeropoint.py 00146952_z_DECam.16.p.w.txt y
To save the result as a catalog:
python zeropoint.py 00146952_z_DECam.16.p.w.txt y catalog.txt
To produce a catalog of all objects possible in a field, run:
import get_SEDs as gs
c = gs.catalog( (314.136483, -6.081352), 900. )
# catalog of objects in a 1/4 degree (900") field centered at RA,Dec = 314.136483, -6.081352
# can run anywhere in the sky, in or out of SDSS footprint
Catalog entries are accessible as:
c.coords
c.SEDs
And you can save the catalog to an ascii file:
c.save_catalog( 'catalog.txt' )