TILEID-targ.fits

Summary:: This file contains the primary science targets covered by the tile disk-footprint.
Naming Convention:: {TILEID}-targ.fits, where {TILEID} is the zero-padded, 6-digit TILED.
Regex:: [0-9]{6}-targ\.fits
File Type:: FITS, 11 MB

Contents

Number	EXTNAME	Type	Contents
HDU0		IMAGE	Empty HDU
HDU1	TARGETS	BINTABLE	Primary science targets covered by the tile disk-footprint.

FITS Header Units

HDU0

This HDU has no non-standard required keywords.

Empty HDU.

HDU1

EXTNAME = TARGETS

Primary science targets covered by the tile disk-footprint: those are read from the MTL ledgers and desitarget catalogs and provided as input to fiberassign.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	382	int	width of table in bytes
NAXIS2	30866	int	number of rows in table
SURVEY	main	str
RESOLVE	T	bool
MASKBITS	T	bool
BACKUP	F	bool
NOSEC [1]	F	bool
DR	None	Unknown

Required Data Table Columns

Name	Type	Units	Description
RELEASE	int16		Imaging surveys release ID
BRICKID	int32		Brick ID from tractor input
BRICKNAME	char[8]		Brick name from tractor input
BRICK_OBJID	int32		Imaging Surveys OBJID on that brick
MORPHTYPE	char[4]		Imaging Surveys morphological type from Tractor
EBV	float32	mag	Galactic extinction E(B-V) reddening from SFD98
FLUX_G	float32	nanomaggy	Flux in the Legacy Survey g-band (AB)
FLUX_R	float32	nanomaggy	Flux in the Legacy Survey r-band (AB)
FLUX_Z	float32	nanomaggy	Flux in the Legacy Survey z-band (AB)
FLUX_IVAR_G	float32	nanomaggy^-2	Inverse variance of FLUX_G (AB)
FLUX_IVAR_R	float32	nanomaggy^-2	Inverse variance of FLUX_R (AB)
FLUX_IVAR_Z	float32	nanomaggy^-2	Inverse variance of FLUX_Z (AB)
FLUX_W1	float32	nanomaggy	WISE flux in W1 (AB)
FLUX_W2	float32	nanomaggy	WISE flux in W2 (AB)
FLUX_IVAR_W1	float32	nanomaggy^-2	Inverse variance of FLUX_W1 (AB)
FLUX_IVAR_W2	float32	nanomaggy^-2	Inverse variance of FLUX_W2 (AB)
FIBERFLUX_G	float32	nanomaggy	Predicted g-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing
FIBERFLUX_R	float32	nanomaggy	Predicted r-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing
FIBERFLUX_Z	float32	nanomaggy	Predicted z-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing
FIBERTOTFLUX_G	float32	nanomaggy	Predicted g-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing
FIBERTOTFLUX_R	float32	nanomaggy	Predicted r-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing
FIBERTOTFLUX_Z	float32	nanomaggy	Predicted z-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing
MASKBITS	int16		Bitwise mask from the imaging indicating potential issue or blending
SHAPE_R	float32	arcsec	Half-light radius of galaxy model (greater than 0)
SHAPE_E1	float32		Ellipticity component 1 of galaxy model for galaxy type MORPHTYPE
SHAPE_E2	float32		Ellipticity component 2 of galaxy model for galaxy type MORPHTYPE
SERSIC	float32		Power-law index for the Sersic profile model (MORPHTYPE=’SER’)
REF_ID	int64		Tyc11,000,000+Tyc210+Tyc3 for Tycho-2; `sourceid` for Gaia DR2
REF_CAT	char[2]		Reference catalog source for star: ‘T2’ for Tycho-2, ‘G2’ for Gaia DR2, ‘L2’ for the SGA, empty otherwise
GAIA_PHOT_G_MEAN_MAG	float32	mag	Gaia G band magnitude
GAIA_PHOT_BP_MEAN_MAG	float32	mag	Gaia BP band magnitude
GAIA_PHOT_RP_MEAN_MAG	float32	mag	Gaia RP band magnitude
PHOTSYS	char[1]		‘N’ for the MzLS/BASS photometric system, ‘S’ for DECaLS
TARGETID	int64		Unique DESI target ID
RA	float64	deg	Barycentric Right Ascension in ICRS
DEC	float64	deg	Barycentric declination in ICRS
REF_EPOCH	float32	yr	Reference epoch for Gaia/Tycho astrometry. Typically 2015.5 for Gaia
PARALLAX	float32	mas	Reference catalog parallax
PMRA	float32	mas / yr	proper motion in the +RA direction (already including cos(dec))
PMDEC	float32	mas / yr	Proper motion in the +Dec direction
DESI_TARGET	int64		DESI (dark time program) target selection bitmask
BGS_TARGET	int64		BGS (Bright Galaxy Survey) target selection bitmask
MWS_TARGET	int64		Milky Way Survey targeting bits
SUBPRIORITY	float64		Random subpriority [0-1) to break assignment ties
OBSCONDITIONS	int32		Bitmask of allowed observing conditions
PRIORITY_INIT	int64		Target initial priority from target selection bitmasks and OBSCONDITIONS
NUMOBS_INIT	int64		Initial number of observations for target calculated across target selection bitmasks and OBSCONDITIONS
SCND_TARGET	int64		Target selection bitmask for secondary programs
NUMOBS_MORE	int64		Number of additional observations needed
NUMOBS	int64		Number of spectroscopic observations (on this specific, single tile)
Z	float64		Redshift measured by Redrock
ZWARN	int64		Redshift warning bitmask from Redrock
ZTILEID	int32		ID of tile that most recently updated target’s state
Z_QN	float64		Redshift measured by QuasarNET using line with highest confidence
IS_QSO_QN	int16		Spectroscopic classification from QuasarNET (1 for a quasar)
DELTACHI2	float64		chi2 difference between first- and second-best redrock template fits
TARGET_STATE	char[30]		Combination of target class and its current observational state
TIMESTAMP	char[25]	s	UTC/ISO time at which the target state was updated
VERSION	char[14]		Tag of desitarget used to create the target catalog
PRIORITY	int64		Target current priority
PLATE_RA	float64	deg	Barycentric Right Ascension in ICRS to be used by PlateMaker
PLATE_DEC	float64	deg	Barycentric Declination in ICRS to be used by PlateMaker
PLATE_REF_EPOCH	float32	yr	Copy of REF_EPOCH to be used by PlateMaker

Notes and Examples

For the SURVEY=cmx m33 tile (TILEID=80615) tile and all the SURVEY=sv1 tiles (except TILEID=80971-80976, the dc3r2 ones), proper-motion correction was applied at the fiberassign design step; thus the following columns can have different values than in the desitarget products: TARGET_RA, TARGET_DEC, REF_EPOCH, PLATE_RA, PLATE_DEC, and PLATE_REF_EPOCH.

Some units in this file do not conform to the FITS standard:

nanomaggy^-2 is incorrectly recorded as 1/nanomaggy^2

Such issues can typically be fixed by parsing the unit through astropy after reading in a Table, e.g.:

import astropy.units as u
from astropy.table import Table
objs = Table.read(filename, 1)
u.Unit(str(objs["FLUX_IVAR_Z"].unit))