targets-dr6

Summary:: DESI target selection files contain a single binary table covering the entire footprint. They contain the variables used by target selection (e.g. fluxes), variables needed by fiber assignment (e.g. RA, DEC), and variables needed for traceability (e.g. TARGETFLAG, TARGETID).
Naming Convention:: targets-DRX-VERSION.fits, where DRX is the imaging surveys data release name (e.g. dr4) and VERSION is the desitarget code version defining the cuts.
Regex:: targets-dr[0-9]+-v?[0-9]+\.[0-9]+(\.[0-9]+|)\.fits
File Type:: FITS, 3 GB

Note: this documents the target catalog format starting with DR4 / desitarget 0.14.0 . The previous format is documented in targets-dr3.

Contents

Number	EXTNAME	Type	Contents
HDU0	PRIMARY	IMAGE	Empty
HDU1	TARGETS	BINTABLE	Target table

FITS Header Units

HDU0

EXTNAME = PRIMARY

This HDU has no non-standard required keywords.

Empty HDU.

HDU1

EXTNAME = TARGETS

Target selection table

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	176	int	width of table in bytes
NAXIS2	15050911	int	number of rows in table
ENCODING	ascii	str
SEED	1028862084	int	initial random seed
HPXNSIDE	64	int	HEALPix nside
HPXNEST	T	bool	HEALPix nested (not ring) ordering

Required Data Table Columns

Name	Type	Description
BRICKID	int32	Brick ID from tractor input
BRICKNAME	char[8]	Brick name from tractor input
BRICK_OBJID	int32	OBJID (unique to brick, but not to file)
RA	float64	Right ascension [degrees]
DEC	float64	Declination [degrees]
FLUX_G	float32	DECaLS flux from tractor input (g)
FLUX_R	float32	DECaLS flux from tractor input (r)
FLUX_Z	float32	DECaLS flux from tractor input (z)
FLUX_W1	float32	WISE flux in W1
FLUX_W2	float32	WISE flux in W2
MW_TRANSMISSION_G	float32	Milky Way dust transmission in DECaLS g
MW_TRANSMISSION_R	float32	Milky Way dust transmission in DECaLS r
MW_TRANSMISSION_Z	float32	Milky Way dust transmission in DECaLS z
MW_TRANSMISSION_W1	float32	Milky Way transmission in WISE W1
MW_TRANSMISSION_W2	float32	Milky Way transmission in WISE W2
PSFDEPTH_G	float32	PSF-based depth in DECaLS g
PSFDEPTH_R	float32	PSF-based depth in DECaLS r
PSFDEPTH_Z	float32	PSF-based depth in DECaLS z
GALDEPTH_G	float32	Model-based depth in DECaLS g
GALDEPTH_R	float32	Model-based depth in DECaLS r
GALDEPTH_Z	float32	Model-based depth in DECaLS z
PSFDEPTH_W1	float32	PSF-based depth in WISE W1
PSFDEPTH_W2	float32	PSF-based depth in WISE W2
SHAPEDEV_R	float32	Half-light radius of deVaucouleurs model (>0)
SHAPEDEV_E1	float32	Ellipticity parameter e1 of deVaucouleurs model
SHAPEDEV_E2	float32	Ellipticity parameter e2 of deVaucouleurs model
SHAPEEXP_R	float32	Half-light radius of exponential model (>0)
SHAPEEXP_E1	float32	Ellipticity parameter e1 of exponential model
SHAPEEXP_E2	float32	Ellipticity parameter e1 of exponential model
SUBPRIORITY	float64	Random subpriority [0-1] to break assignment ties
TARGETID	int64	Unique targeting ID
DESI_TARGET	int64	DESI (dark time program) target selection bitmask
BGS_TARGET	int64	BGS (bright time program) target selection bitmask
MWS_TARGET	int64	MWS (bright time program) target selection bitmask
HPXPIXEL	int64	HEALPixel containing target.

Notes and Examples

In general, the above format contains:

Columns that were used by target selection (e.g. FLUX_G/R/Z)
Columns needed by fiber assignment (e.g. RA, DEC)
Columns needed for traceability (e.g. BRICKNAME, TARGETID, DESI_TARGET, BGS_TARGET, MWS_TARGET)

TARGETID, HPXPIXEL, PHOTSYS, DESI_TARGET, BGS_TARGET and MWS_TARGET are created by target selection; the rest are passed through from the original input tractor files

See http://legacysurvey.org for more details about the columns from input tractor files