DESCRIPTION_OF_OUTPUTS.md

What Legacyzpts Creates

Four FITS data tables with the same columns and units for all three cameras.

(1) -zpt.fits

Name	Type	Units	Description
airmass	float32	----	from CP header
avsky	float32	----	from CP header
camera	str	----	decam, mosaic, or 90prime
ccdname	str	----	ccd[1-4] (mosaic,90prime) or [NS][0-9]{2} (decam)
ccdnum	int16	----	ccdname with alphabetic characters removed
cd1_1	float32	----	Astrometric solution
cd1_2	float32	----	Astrometric solution
cd2_1	float32	----	Astrometric solution
cd2_2	float32	----	Astrometric solution
crpix1	float32	----	Astrometric solution
crpix2	float32	----	Astrometric solution
crval1	float64	----	Astrometric solution
crval2	float64	----	Astrometric solution
date_obs	str	----	yyyy-mm-dd
dec	float64	deg	WCS solution center of the CCD
dec_bore	float64	deg	bore sight of telescope
decoff	float32	deg	Median of 3 sigma-clipped ("Gaia Dec" - dec)
decrms	float32	deg	RMS of 3 sigma-clipped ("Gaia Dec" - dec)
decstddev	float32	deg	Std Dev of 3 sigma-clipped ("Gaia Dec" - dec)
err_message	str	----	empty string if no processing problems, otherwise usually describes a reason why this CCD should be excluded from science analysis
expid	str	----	expnum + ccdname
expnum	int32	----	primary key
exptime	float32	sec	exposure time
filter	str	----	g, r, or z
fwhm	float32	pixel	measured by legacyzpts
fwhm_cp	float32	pixel	from CP header
gain	float32	e-/ADU	(Decam) average of GAINA, GAINB, (Mosaic) GAIN, (90prime) 1.4
goodps1	int16	----	number of good PS1 sources in CCD
goodps1_wbadpix5	int16	----	number of good PS1 sources in the CCD that are within 5 pixels of at least bad pixel map == 5 pixel
ha	str	N/A	hh:mm:ss.ss
height	int16	pixel	height of CCD
image_filename	str	----	path to image on NERSC machines, relative to /project/projectdirs/cosmo/staging
image_hdu	int16	----	hdu number for the ccd in the image FITS file
mjd_obs	float64	----	Modified Julian Date
nmatch_astrom	int16	----	number of good detected sources that have good Gaia matches within 1''
nmatch_photom	int16	----	number of good detected sources that have good PS1 matches within 1''
object	str	----	type of exposure (object vs. flat)
phoff	float32	AB mag	Per CCD Median of 2.5 sigma-clipped (PS1 mag - Our mag)
phrms	float32	AB mag	Per CCD Std Dev of 2.5 sigma-clipped (PS1 mag - Our mag)
pixscale	float32	as/pixel	fixed at 0.262 (DECam, Mosaic) and 0.470 (90Prime)
propid	str	----	proposal id for the survey
ra	float64	deg	WCS solution center of the CCD
ra_bore	float64	deg	bore sight of telescope
raoff	float32	deg	Median of 3 sigma-clipped ("Gaia Ra" - ra) * cos(dec)
rarms	float32	deg	RMS of 3 sigma-clipped ("Gaia Ra" - ra) * cos(dec)
rastddev	float32	deg	Std Dev of 3 sigma-clipped("Gaia Ra" - ra) * cos(dec)
skycounts	float32	e-/pixel/sec	Median of 3 sigma-clipped 1000x1000 central pixels of CCD
skymag	float32	AB mag/as^2	skycounts converted to AB mag/as^2
skyrms	float32	e-/pixel/sec	Std Dev of 3 sigma-clipped 1000x1000 central pixels of CCD
transp	float32	----	Relative atmospheric transparency
ut	str	----	hh:mm:ss.ss
width	int16	pixel	width of CCD
zpt	float32	e-/sec	phoff + nominal zeropoint for camera, filter
zptavg	float32	e-/sec	average zpt over all CCDs
zpt_wbadpix5	float32	e-/sec	phoff + nominal zeropoint for camera, filter including sources that have at least one bad pixel map == 5 pixel in their 7'' aperture

(2) -legacyzpt.fits

All of these are duplicates of #1 and are the minimal set required by our legacypipe/Tractor pipeline. Note, the names and units are different from above.

Name	Type	Decam	Mosaic/90Prime	Description
camera	str	----	----	same as above
ccddecoff	float64	deg	deg	decoff
ccdname	str	----	----	same as above
ccdnmatch	int16	----	----	nmatch_photom
ccdraoff	float64	deg	deg	raoff
ccdzpt	float32	ADU/sec	e-/sec	zpt
cd1_1	float32	----	----	same as above
cd1_2	float32	----	----	same as above
cd2_1	float32	----	----	same as above
cd2_2	float32	----	----	same as above
crpix1	float32	----	----	same as above
crpix2	float32	----	----	same as above
crval1	float64	----	----	same as above
crval2	float64	----	----	same as above
dec	float64	deg	deg	same as above
dec_bore	float64	deg	deg	same as above
expnum	int32	----	----	same as above
exptime	float32	sec	sec	same as above
filter	str	----	----	same as above
fwhm	float32	pixel	pixel	same as above
height	int16	pixel	pixel	same as above
image_filename	str	----	----	same as above
image_hdu	int16	----	----	same as above
mjd_obs	float64	----	----	same as above
object	str	----	----	same as above
propid	str	----	----	same as above
ra	float64	deg	deg	same as above
ra_bore	float64	deg	deg	same as above
skyrms	float32	e-/pixel/sec	e-/pixel/sec	same as above
width	int16	pixel	pixel	same as above
zpt	float32	ADU/sec	e-/sec	zptavg

(3) Two stars tables

There are two stars tables: -star-photom.fits and -star-astrom.fits. Both have this base set of columns

Name	Type	Units	Description
ccdname	str	----	same as above
dec	float64	deg	declination of detected source
expnum	int32	----	same as above
expid	str	----	same as above
exptime	float32	sec	same as above
filter	str	----	same as above
gain	float32	----	same as above
image_filename	str	----	same as above
image_hdu	int16	----	same as above
nmatch	int16	----	number of good detected sources with good PS1 (stars-photom.fits) or Gaia (stars-astrom.fits) 1'' matches
ra	float64	deg	right ascension of detected source
x	float64	pixel	x-position of detected source, [0,width]
y	float64	pixel	y-position of detected source, [0,height]

(3a) -star-photom.fits

The photom table has additional photometry information for 1 as matched PS1 sources

Name	Type	Units	Description
apflux	float64	e-	number e- in 7'' aperture minus apskyflux
apmag	float64	AB mag	apflux converted to AB Mag
apskyflux	float64	e-	number e- from local sky in 7'' aperture
apskyflux_perpix	float64	e-/pixel	number e- from local sky per pixel
dmagall	float64	AB mag	PS1 mag minus apmag
gaia_g	float64	AB mag	gaia g-band mag
ps1_mag	float32	AB mag	PS1 mag converted to either decam,mosaic,90prime system
ps1_g	float64	AB mag	PS1 g-mag
ps1_r	float64	AB mag	PS1 r-mag
ps1_i	float64	AB mag	PS1 i-mag
ps1_z	float64	AB mag	PS1 z-mag

(3b) -star-astrom.fits

The astrom table has additional astrometry information for 1 as matched Gaia sources (or PS1 sources if < 20 Gaia sources).

Name	Type	Units	Description
decdiff	float64	deg	"Gaia Dec" - dec
radiff	float64	deg	("Gaia Ra" - ra) * cos(dec)