=============== TILEID-gfa.fits =============== :Summary: This file contains the stars for the ETC / GUIDE / FOCUS covered by the tile disk-footprint. :Naming Convention: ``{TILEID}-gfa.fits``, where ``{TILEID}`` is the zero-padded, 6-digit TILED. :Regex: ``[0-9]{6}-gfa\.fits`` :File Type: FITS, 6 MB Contents ======== ====== ======= ======== ===================================================================== Number EXTNAME Type Contents ====== ======= ======== ===================================================================== HDU0_ IMAGE Empty HDU HDU1_ TARGETS BINTABLE Stars for the ETC / GUIDE / FOCUS covered by the tile disk-footprint. ====== ======= ======== ===================================================================== FITS Header Units ================= HDU0 ---- This HDU has no non-standard required keywords. Empty HDU. HDU1 ---- EXTNAME = TARGETS Stars for the ETC / GUIDE / FOCUS covered by the tile disk-footprint: those are read from the desitarget catalogs and provided as input to fiberassign. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ============= ==== ======================= KEY Example Value Type Comment ======== ============= ==== ======================= NAXIS1 164 int width of table in bytes NAXIS2 43904 int number of rows in table SURVEY main str RESOLVE T bool MASKBITS T bool BACKUP F bool NOSEC F bool DR 9 int ======== ============= ==== ======================= Required Data Table Columns ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. rst-class:: 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 RA float64 deg Barycentric Right Ascension in ICRS DEC float64 deg Barycentric declination in ICRS RA_IVAR float32 deg^-2 Inverse variance of RA (no cosine term!), excluding astrometric calibration errors DEC_IVAR float32 deg^-2 Inverse variance of DEC, excluding astrometric calibration errors 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 Tyc1*1,000,000+Tyc2*10+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 proper motion in the +RA direction (already including cos(dec)) PMDEC float32 mas / yr 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 int32 Gaia G band number of observations HPXPIXEL int64 HEALPixel containing this location at NSIDE=64 in the NESTED scheme ================================= ======= ============ ======================================================================================================================================= Notes and Examples ================== Some units in this file do not conform to the FITS standard: * deg^-2 is incorrectly recorded as 1/deg^2 * nanomaggy^-2 is incorrectly recorded as 1/nanomaggy^2 * mas^-2 is incorrectly recorded as 1/mas^2 Such issues can typically be fixed by parsing the unit through astropy after reading in a Table, e.g.: .. code-block:: python import astropy.units as u from astropy.table import Table objs = Table.read(filename, 1) u.Unit(str(objs["RA_IVAR"].unit))