“standalone” secondary targets

Summary:: DESI “standalone” secondary targets are stored in single, monolithic binary tables. Here, “standalone” refers to the fact that either the proposer of the particular secondary target class requested that their targets should not be merged with matching primary targets, or that no match was found to a primary target.
Naming Convention:: PHASEtargets-OBSCON-secondary.fits, where PHASE is a specific DESI observational phase (e.g. svX with X=1,2,3 for iterations of Survey Validation), and OBSCON is the observing condition or “layer”) for the targets (e.g. dark).
Regex:: (cmx|sv1|sv2|sv3|main2|)targets-(bright|dark)-secondary(-dr9photometry)?\.fits
File Type:: FITS, 200-900 MB

Contents

Number	EXTNAME	Type	Contents
HDU0		IMAGE	Empty
HDU1	SCND_TARGETS	BINTABLE	Table of secondary targets

This HDU has no non-standard required keywords.

Empty HDU.

EXTNAME = SCND_TARGETS

Table of secondary targets

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	121	int	width of table in bytes
NAXIS2	7125595	int	number of rows in table
SURVEY	“main”	str	svX for SV, main for Main Survey
PRIMDIR	“/global/”	str	location of directory of information about corresponding primary targets
SEP	1.0	float	matching radius that was used to find primary targets (arcsec)
MASKED	T	bool	`True` if targets were masked to avoid bright sources
MASKDIR	“masks/”	str	location of directory of masks used to avoid bright sources
SCNDDIR	“/global/”	str	directory from which secondary targets were read
OBSCON	“DARK”	str	observing layer for file
SUBPSEED	717	int	random seed used to generate SUBPRIORITY values

Name	Type	Units	Description
RA	float64	deg	Right ascension
DEC	float64	deg	Declination
PMRA	float32	mas / yr	Reference catalog proper motion in the RA direction
PMDEC	float32	mas / yr	Reference catalog proper motion in the Dec direction
REF_EPOCH	float32	yr	Reference epoch for Gaia/Tycho astrometry. Typically 2015.5 for Gaia.
OVERRIDE	logical		`True` if the secondary target class was not matched to primary targets
FLUX_G	float32	nanomaggy	LS flux from tractor input (g)
FLUX_R	float32	nanomaggy	LS flux from tractor input (r)
FLUX_Z	float32	nanomaggy	LS flux from tractor input (z)
PARALLAX	float32	mas	Reference catalog parallax
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
GAIA_ASTROMETRIC_EXCESS_NOISE	float32		Gaia astrometric excess noise
TARGETID	int64		Unique targeting ID
DESI_TARGET	int64		DESI (dark time program) target selection bitmask
SCND_TARGET	int64		SCND (secondary program) target selection bitmask
SCND_ORDER	int32		Row in which this target appeared in the input secondary target file
SUBPRIORITY	float64		Random subpriority [0-1] to break assignment ties
OBSCONDITIONS	int64		Flag target to be observed in combinations of dark/bright observing layer
PRIORITY_INIT	int64		Initial priority for target calculated across target selection bitmasks and OBSCONDITIONS
NUMOBS_INIT	int64		Initial number of observations for target calculated across target selection bitmasks and OBSCONDITIONS