zpix-SURVEY-PROGRAM-expfibermap.fits

Summary:

Per-exposure fibermap entries for the healpix-based redshift catalogs, one file per SURVEY and PROGRAM.

Naming Convention:

zcatalog/v2/SURVEY/exp_fibermap/zpix-SURVEY-PROGRAM-expfibermap.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)-expfibermap\.fits

File Type:

FITS, ~500 MB

Contents

Number	EXTNAME	Type	Contents
HDU0	PRIMARY	IMAGE	Empty
HDU1	EXP_FIBERMAP	BINTABLE	Per-exposure entries from input fibermaps

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 = EXP_FIBERMAP

Input fibermap entries for columns that apply per-exposure and cannot be coadded, e.g. the individual TILEIDs and FIBERs on which each target was observed. Each row corresponds to one exposure of one target; a single target may appear many times if observed on multiple exposures or tiles.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	162	int	width of table in bytes
NAXIS2	1374500	int	number of rows in table
CHECKSUM	diandZUmdfamdZUm	str	HDU checksum
DATASUM	2531100066	str	data unit checksum

Required Data Table Columns

Name	Type	Units	Description
TARGETID	int64		Unique DESI target ID
PRIORITY	int32		Target current priority
SUBPRIORITY	float64		Random subpriority [0-1) to break assignment ties
NIGHT	int32		Night of observation (YYYYMMDD) starting at local noon before observations start
EXPID	int32		DESI Exposure ID number
MJD	float64		Modified Julian Date when shutter was opened for this exposure
TILEID	int32		Unique DESI tile ID
EXPTIME	float64	s	Length of time shutter was open
PETAL_LOC	int16		Petal location [0-9]
DEVICE_LOC	int32		Device location on focal plane [0-523]
LOCATION	int64		Location on the focal plane PETAL_LOC*1000 + DEVICE_LOC
FIBER	int32		Fiber ID on the CCDs [0-4999]
FIBERSTATUS	int32		Fiber status mask. 0=good
FIBERASSIGN_X	float32	mm	Fiberassign expected CS5 X location on focal plane
FIBERASSIGN_Y	float32	mm	Fiberassign expected CS5 Y location on focal plane
LAMBDA_REF	float32	Angstrom	Requested wavelength at which targets should be centered on fibers
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
NUM_ITER	int64		Number of positioner iterations
FIBER_X	float64	mm	CS5 X location requested by PlateMaker
FIBER_Y	float64	mm	CS5 Y location requested by PlateMaker
DELTA_X	float64	mm	CS5 X requested minus actual position
DELTA_Y	float64	mm	CS5 Y requested minus actual position
FIBER_RA	float64	deg	RA of actual fiber position
FIBER_DEC	float64	deg	DEC of actual fiber position
PSF_TO_FIBER_SPECFLUX	float64		fraction of light from point-like source captured by 1.5 arcsec diameter fiber given atmospheric seeing
IN_COADD_B	logical		If True this fiber in this exposure was used in the coadd of camera B
IN_COADD_R	logical		If True this fiber in this exposure was used in the coadd of camera R
IN_COADD_Z	logical		If True this fiber in this exposure was used in the coadd of camera Z

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.

For targets with a non-zero proper motion, FIBER_RA and FIBER_DEC refer to the position at the reference epoch (but note that the proper-motion correction has been applied at the time of the observation, it is just not recorded in FIBER_RA and FIBER_DEC).