zpix-SURVEY-PROGRAM.fits

Summary:

Core redshift and targeting columns from the healpix-based redshift catalogs, one file per SURVEY and PROGRAM.

Naming Convention:

zcatalog/v2/SURVEY/zpix-SURVEY-PROGRAM.fits, where SURVEY is e.g. main or sv1 and PROGRAM is e.g. bright or dark.

Regex:

zpix-(cmx|main|sv1|sv2|sv3|special)-(backup|bright|dark|other)\.fits

File Type:

FITS, ~100 MB

Contents

Number	EXTNAME	Type	Contents
HDU0	PRIMARY	IMAGE	Empty
HDU1	ZCATALOG	BINTABLE	Core redshift catalog joined with targeting metadata

FITS Header Units

HDU0

EXTNAME = PRIMARY

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
CHECKSUM	9aaGCVYE9aaECUYE	str	HDU checksum
DATASUM	0	str	data unit checksum
ZCATVER	v2	str	Version of zcatalog files

Empty HDU.

HDU1

EXTNAME = ZCATALOG

Core redshift and targeting columns from the healpix-based Redrock redshift catalogs. Imaging photometry columns are in the companion zpix-SURVEY-PROGRAM-imaging.fits file. All remaining columns (full Redrock output, TSNR2, emission lines, QuasarNET, quality flags) are in zpix-SURVEY-PROGRAM-extra.fits.

Z_BEST is the recommended redshift to use. It equals Z (Redrock) for most targets, but is set to Z_QSO (QuasarNET) for confirmed QSO targets where the two differ by more than 1000 km/s. Z_CONF encodes the overall confidence: 0 = no confidence; 1 = ZWARN==0 but not LSS-quality; 3 = passes LSS quality cuts for at least one extragalactic tracer class.

TEMNAMnn and TEMVERnn record the Redrock template names and versions used for the redshift fits.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	261	int	width of table in bytes
NAXIS2	139728	int	number of rows in table
LONGSTRN	OGIP 1.0	str
RRVER	0.15.0	str	Redrock version
TEMNAM00	GALAXY	str	Redrock template 00 name
TEMVER00	2.6	str	Redrock template 00 version
TEMNAM01	QSO:::HIZ	str
TEMVER01	0.1	str
TEMNAM02	QSO:::LOZ	str
TEMVER02	1.0	str
TEMNAM03	STAR:::A	str
TEMVER03	0.1	str
TEMNAM04	STAR:::B	str
TEMVER04	0.1	str
TEMNAM05	STAR:::CV	str
TEMVER05	0.1	str
TEMNAM06	STAR:::F	str
TEMVER06	0.1	str
TEMNAM07	STAR:::G	str
TEMVER07	0.1	str
TEMNAM08	STAR:::K	str
TEMVER08	0.1	str
TEMNAM09	STAR:::M	str
TEMVER09	0.1	str
TEMNAM10	STAR:::WD	str
TEMVER10	0.1	str
SPGRP	healpix	str	Spectral grouping method
HPXNSIDE	64	int	Healpix nside
HPXNEST	T	bool	Nested healpix (not ring)
SURVEY [1]	main	str	DESI sub-survey (e.g. sv1, sv3, main)
PROGRAM [1]	dark	str	DESI program (e.g. dark, bright)
CHECKSUM	QA6lQ26iQ96iQ96i	str	HDU checksum
DATASUM	4284326946	str	data unit checksum
ZCATVER	v2	str	Version of zcatalog files

Required Data Table Columns

Name	Type	Units	Description
TARGETID	int64		Unique DESI target ID
UNIQPIX [1]	int32		Unique HEALPixel identifier encoding both pixel number and NSIDE (DR3+); HEALPIX and NSIDE are in the companion extra file
HEALPIX [1]	int32		HEALPixel containing this location at NSIDE=64 in the NESTED scheme (DR2 only)
Z_BEST	float64		Best redshift: equals Z (Redrock) for most targets, Z_QSO (QuasarNET) for confirmed QSOs where the two differ by >1000 km/s
Z_CONF	uint8		Redshift confidence: 0=no confidence, 1=low confidence (ZWARN==0), 3=high confidence (passes LSS quality cuts)
ZERR_BEST	float64		Redshift error for Z_BEST
ZWARN_BEST	int32		Redshift warning bitmask for Z_BEST
SPECTYPE_BEST	char[6]		Spectral type for Z_BEST (e.g. GALAXY, QSO, STAR)
SUBTYPE_BEST	char[3]		Spectral subtype for Z_BEST
CHI2_BEST	float32		Best fit chi squared for Z_BEST
DELTACHI2_BEST	float32		chi2 difference between first- and second-best fits for Z_BEST
PETAL_LOC	int16		Petal location [0-9]
FIBER	int32		Fiber ID on the CCDs [0-4999]
COADD_FIBERSTATUS	int32		bitwise-AND of input FIBERSTATUS
TARGET_RA	float64	deg	Barycentric Right Ascension in ICRS
TARGET_DEC	float64	deg	Barycentric Declination in ICRS
DESINAME	char[22]		Human readable identifier of a sky location DESI JXXX.XXXX[+/-]YY.YYYY, where X,Y=truncated decimal TARGET_RA, TARGET_DEC, precise to 0.36 arcsec. Multiple objects can map to a single DESINAME if very close on the sky.
OBJTYPE	char[3]		Object type: TGT, SKY, NON, BAD
FIBERASSIGN_X	float32	mm	Fiberassign expected CS5 X location on focal plane
FIBERASSIGN_Y	float32	mm	Fiberassign expected CS5 Y location on focal plane
PRIORITY	int32		Target current priority
CMX_TARGET [1]	int64		Target selection bitmask for commissioning
SV1_DESI_TARGET [1]	int64		DESI (dark time program) target selection bitmask for SV1
SV1_BGS_TARGET [1]	int64		BGS (bright time program) target selection bitmask for SV1
SV1_MWS_TARGET [1]	int64		MWS (bright time program) target selection bitmask for SV1
SV1_SCND_TARGET [1]	int64		Secondary target selection bitmask for SV1
SV2_DESI_TARGET [1]	int64		DESI (dark time program) target selection bitmask for SV2
SV2_BGS_TARGET [1]	int64		BGS (bright time program) target selection bitmask for SV2
SV2_MWS_TARGET [1]	int64		MWS (bright time program) target selection bitmask for SV2
SV2_SCND_TARGET [1]	int64		Secondary target selection bitmask for SV2
SV3_DESI_TARGET [1]	int64		DESI (dark time program) target selection bitmask for SV3
SV3_BGS_TARGET [1]	int64		BGS (bright time program) target selection bitmask for SV3
SV3_MWS_TARGET [1]	int64		MWS (bright time program) target selection bitmask for SV3
SV3_SCND_TARGET [1]	int64		Secondary target selection bitmask for SV3
DESI_TARGET [1]	int64		DESI (dark time program) target selection bitmask
BGS_TARGET [1]	int64		BGS (bright time program) target selection bitmask
MWS_TARGET [1]	int64		MWS (bright time program) target selection bitmask
SCND_TARGET [1]	int64		Secondary target selection bitmask
COADD_NUMEXP	int16		Number of exposures in coadd
COADD_EXPTIME	float32	s	Summed exposure time for coadd
COADD_NUMNIGHT	int16		Number of nights in coadd
COADD_NUMTILE	int16		Number of tiles in coadd
MIN_MJD	float64	d	Minimum value of the Modified Julian Date (when the shutter was open for the first exposure used in the coadded spectrum)
MAX_MJD	float64	d	Maximum value of the Modified Julian Date (when the shutter was open for the last exposure used in the coadded spectrum)
MEAN_MJD	float64	d	Mean value of the Modified Julian Date (when the shutter was open for exposures used in the coadded spectrum)
GOOD_SPEC	logical		True if this is a science target with good hardware/fiber status
EFFTIME_SPEC	float32	s	Effective exposure time for spectroscopy (from TSNR2_LRG; see Notes)
ZCAT_NSPEC	int16		Number of times this TARGETID appears in this catalog
ZCAT_PRIMARY	logical		Boolean flag (True/False) for the primary coadded spectrum in this zcatalog

[1] (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21)

Optional

Notes and Examples

• The targeting bitmasks DESI_TARGET, BGS_TARGET, MWS_TARGET, and SCND_TARGET only apply to SURVEY="main" targets; they are not set for targets in other surveys.

• Similarly, the SV1_DESI_TARGET etc. target masks are only set for the corresponding survey; there is no propagation of targeting bits across surveys.

• GOOD_Z_{BGS,LRG,ELG,QSO} flags are in the companion zpix-SURVEY-PROGRAM-extra.fits file.

• This file does not contain SV_NSPEC, SV_PRIMARY, MAIN_NSPEC, or MAIN_PRIMARY; these are added when zpix files are combined into zall-pix-SPECPROD.fits.

• EFFTIME_SPEC is the effective exposure time computed as SNR2TIME * TSNR2_X, where TSNR2_X is chosen by program: TSNR2_LRG for dark, TSNR2_BGS for bright, TSNR2_GPBBACKUP for backup. SNR2TIME is a per-tracer normalization factor from the TSNR ensemble template files in desimodel.

• 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.