fba-TILEID.fits

Summary:: This type of file is intended to be an “almost complete”, but still intermediate, version of the final fiberassign files.
Naming Convention:: fba-{TILEID}.fits, where {TILEID} is the zero-padded, 6-digit TILED.
Regex:: fba-[0-9]{6}\.fits
File Type:: FITS, 9 MB

Contents

Number	EXTNAME	Type	Contents
HDU0	PRIMARY	IMAGE	Empty HDU.
HDU1	FASSIGN	BINTABLE	Short version of FIBERASSIGN HDU
HDU2	FTARGETS	BINTABLE	Short version of TARGETS HDU
HDU3	FAVAIL	BINTABLE	Equivalent to POTENTIAL_ASSIGNMENTS
HDU4	GFA_TARGETS	BINTABLE	Selected star for the ETC / GUIDE / FOCUS

FITS Header Units

HDU0

EXTNAME = PRIMARY

This HDU contains header keywords only.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type
TILEID	1774	int
TILERA	222.786	float
TILEDEC	41.722	float
FIELDROT	-0.113900362856195	float
FA_PLAN	2022-07-01T00:00:00.000	str
FA_HA	10.15	float
FA_RUN	2021-05-18T21:57:00+00:00	str
FA_M_GFA [1]	0.4	float
FA_M_PET [1]	0.4	float
FA_M_POS [1]	0.05	float
REQRA	222.786	float
REQDEC	41.722	float
FIELDNUM	0	int
FA_VER	4.0.0	str
FA_SURV	main	str

Empty HDU.

HDU1

EXTNAME = FASSIGN

Short version of FIBERASSIGN HDU.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	66	int	width of table in bytes
NAXIS2	5020	int	number of rows in table
TILEID	1774	int
TILERA	222.786	float
TILEDEC	41.722	float
FIELDROT	-0.113900362856195	float
FA_PLAN	2022-07-01T00:00:00.000	str
FA_HA	10.15	float
FA_RUN	2021-05-18T21:57:00+00:00	str
FA_M_GFA [1]	0.4	float
FA_M_PET [1]	0.4	float
FA_M_POS [1]	0.05	float
REQRA	222.786	float
REQDEC	41.722	float
FIELDNUM	0	int
FA_VER	4.0.0	str
FA_SURV	main	str

Required Data Table Columns

Name	Type	Units	Description
FIBER	int32		Fiber ID on the CCDs [0-4999]
TARGETID	int64		Unique DESI target ID
LOCATION	int32		Location on the focal plane PETAL_LOC*1000 + DEVICE_LOC
FIBERSTATUS	int32		Fiber status mask. 0=good
LAMBDA_REF	float32	Angstrom	Requested wavelength at which targets should be centered on fibers
PETAL_LOC	int16		Petal location [0-9]
DEVICE_LOC	int32		Device location on focal plane [0-523]
DEVICE_TYPE	char[3]		Device type
TARGET_RA	float64	deg	Barycentric right ascension in ICRS
TARGET_DEC	float64	deg	Barycentric declination in ICRS
FA_TARGET	int64		Targeting bit internally used by fiberassign (linked with FA_TYPE)
FA_TYPE	binary		Fiberassign internal target type (science, standard, sky, safe, suppsky)
FIBERASSIGN_X	float32	mm	Fiberassign expected CS5 X location on focal plane
FIBERASSIGN_Y	float32	mm	Fiberassign expected CS5 Y location on focal plane
PLATE_RA [1]	float64	deg	Barycentric Right Ascension in ICRS to be used by PlateMaker
PLATE_DEC [1]	float64	deg	Barycentric Declination in ICRS to be used by PlateMaker

HDU2

EXTNAME = FTARGETS

Short version of TARGETS.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	49	int	width of table in bytes
NAXIS2	146897	int	number of rows in table
TILEID	1774	int
TILERA	222.786	float
TILEDEC	41.722	float
FIELDROT	-0.113900362856195	float
FA_PLAN	2022-07-01T00:00:00.000	str
FA_HA	10.15	float
FA_RUN	2021-05-18T21:57:00+00:00	str
FA_M_GFA [1]	0.4	float
FA_M_PET [1]	0.4	float
FA_M_POS [1]	0.05	float
REQRA	222.786	float
REQDEC	41.722	float
FIELDNUM	0	int
FA_VER	4.0.0	str
FA_SURV	main	str

Required Data Table Columns

Name	Type	Units	Description
TARGETID	int64		Unique DESI target ID
TARGET_RA	float64	deg	Barycentric right ascension in ICRS
TARGET_DEC	float64	deg	Barycentric declination in ICRS
FA_TARGET	int64		Targeting bit internally used by fiberassign (linked with FA_TYPE)
FA_TYPE	binary		Fiberassign internal target type (science, standard, sky, safe, suppsky)
PRIORITY	int32		Target current priority
SUBPRIORITY	float64		Random subpriority [0-1) to break assignment ties
OBSCONDITIONS	int32		Bitmask of allowed observing conditions
PLATE_RA [1]	float64	deg	Barycentric Right Ascension in ICRS to be used by PlateMaker
PLATE_DEC [1]	float64	deg	Barycentric Declination in ICRS to be used by PlateMaker

HDU3

EXTNAME = FAVAIL

Equivalent to POTENTIAL_ASSIGNMENTS HDU.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	16	int	width of table in bytes
NAXIS2	163517	int	number of rows in table
TILEID	1774	int
TILERA	222.786	float
TILEDEC	41.722	float
FIELDROT	-0.113900362856195	float
FA_PLAN	2022-07-01T00:00:00.000	str
FA_HA	10.15	float
FA_RUN	2021-05-18T21:57:00+00:00	str
FA_M_GFA [1]	0.4	float
FA_M_PET [1]	0.4	float
FA_M_POS [1]	0.05	float
REQRA	222.786	float
REQDEC	41.722	float
FIELDNUM	0	int
FA_VER	4.0.0	str
FA_SURV	main	str

Required Data Table Columns

Name	Type	Description
LOCATION	int32	Location on the focal plane PETAL_LOC*1000 + DEVICE_LOC
FIBER	int32	Fiber ID on the CCDs [0-4999]
TARGETID	int64	Unique DESI target ID

HDU4

EXTNAME = GFA_TARGETS

GFA stars to be used by the ETC / GUIDE / FOCUS

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	168	int	width of table in bytes
NAXIS2	820	int	number of rows in table

Required Data Table Columns

Name	Type	Units	Description
RELEASE	int32		Imaging surveys release ID
TARGETID	int64		Unique DESI target ID
BRICKID	int32		Brick ID from tractor input
BRICK_OBJID	int32		Imaging Surveys OBJID on that brick
TARGET_RA	float64	deg	Barycentric right ascension in ICRS
TARGET_DEC	float64	deg	Barycentric declination in ICRS
TARGET_RA_IVAR	float32		label for field 7
TARGET_DEC_IVAR	float32		label for field 8
MORPHTYPE	char[4]		Imaging Surveys morphological type from Tractor
MASKBITS	int16		Bitwise mask from the imaging indicating potential issue or blending
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)
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
REF_EPOCH	float32	yr	Reference epoch for Gaia/Tycho astrometry. Typically 2015.5 for Gaia
PARALLAX	float32	mas	Reference catalog parallax
PARALLAX_IVAR	float32	mas^-2	Inverse variance of PARALLAX
PMRA	float32	mas yr^-1	proper motion in the +RA direction (already including cos(dec))
PMDEC	float32	mas yr^-1	Proper motion in the +Dec direction
PMRA_IVAR	float32	yr^2 mas^-2	Inverse variance of PMRA
PMDEC_IVAR	float32	yr^2 mas^-2	Inverse variance of PMDEC
GAIA_PHOT_G_MEAN_MAG	float32	mag	Gaia G band magnitude
GAIA_PHOT_G_MEAN_FLUX_OVER_ERROR	float32		Gaia G band signal-to-noise
GAIA_PHOT_BP_MEAN_MAG	float32	mag	Gaia BP band magnitude
GAIA_PHOT_BP_MEAN_FLUX_OVER_ERROR	float32		Gaia BP band signal-to-noise
GAIA_PHOT_RP_MEAN_MAG	float32	mag	Gaia RP band magnitude
GAIA_PHOT_RP_MEAN_FLUX_OVER_ERROR	float32		Gaia RP band signal-to-noise
GAIA_ASTROMETRIC_EXCESS_NOISE	float32		Gaia astrometric excess noise
URAT_ID	int64		ID in the URAT catalog for sources where URAT supplemented missing Gaia astrometric information
URAT_SEP	float32	arcsec	Separation between URAT and Gaia sources where URAT supplemented missing Gaia astrometric information
GAIA_PHOT_G_N_OBS [1]	int32		Gaia G band number of observations
HPXPIXEL	int64		HEALPixel containing this location at NSIDE=64 in the NESTED scheme
GFA_LOC	int16		label for field 36
ETC_FLAG	int16		label for field 37
GUIDE_FLAG	int16		label for field 38
FOCUS_FLAG	int16		label for field 39

Notes and Examples

This type of file contains only what is strictly needed or generated by fiber assignment itself, while the final fiberassign-TILEID.fits.gz files also have merged in targeting information, and some bookkeeping changes such as splitting the 20 sky monitor fibers separate from the 5000 science fibers, and renaming/reordering HDUs.