================================ coadd-SURVEY-PROGRAM-PIXNUM.fits ================================ :Summary: This holds the calibrated coadded spectra organized by healpix location on the sky. :Naming Convention: ``coadd-SURVEY-PROGRAM-PIXNUM.fits``, where ``SURVEY`` is *e.g.* ``main`` or ``sv1``, ``PROGRAM`` is *e.g.* ``bright`` or ``dark`` and ``PIXNUM`` is the HEALPixel number. :Regex: ``coadd-(cmx|main|special|sv1|sv2|sv3)-(backup|bright|dark|other)-[0-9]+\.fits`` :File Type: FITS, 219 MB This file follows nearly the same format as the :doc:`spectra files `, except there is one entry per target instead of one entry per exposure per target, and the FIBERMAP replaces some exposure-specific columns with summary columns, e.g. ``NIGHT`` becomes ``FIRST_NIGHT``, ``LAST_NIGHT``, and ``NUM_NIGHT``. Contents ======== ====== ============ ======== =================== Number EXTNAME Type Contents ====== ============ ======== =================== HDU00_ IMAGE Keywords only HDU01_ FIBERMAP BINTABLE fibermap table HDU02_ EXP_FIBERMAP BINTABLE Per-exposure entries from input fibermaps HDU03_ B_WAVELENGTH IMAGE Wavelength array of b-channel spectra HDU04_ B_FLUX IMAGE Flux of b-channel spectra HDU05_ B_IVAR IMAGE Inverse variance of b-channel spectra HDU06_ B_MASK BINTABLE Mask of b-channel spectra HDU07_ B_RESOLUTION IMAGE Resolution matrices of b-channel spectra HDU08_ R_WAVELENGTH IMAGE Wavelength array of r-channel spectra HDU09_ R_FLUX IMAGE Flux of r-channel spectra HDU10_ R_IVAR IMAGE Inverse variance of r-channel spectra HDU11_ R_MASK BINTABLE Mask of r-channel spectra HDU12_ R_RESOLUTION IMAGE Resolution matrices of r-channel spectra HDU13_ Z_WAVELENGTH IMAGE Wavelength array of z-channel spectra HDU14_ Z_FLUX IMAGE Flux of z-channel spectra HDU15_ Z_IVAR IMAGE Inverse variance of z-channel spectra HDU16_ Z_MASK BINTABLE Mask of z-channel spectra HDU17_ Z_RESOLUTION IMAGE Resolution matrices of z-channel spectra HDU18_ SCORES BINTABLE scores table ====== ============ ======== =================== Note: the above is the order in which these HDUs appear in DESI spectroscopic pipeline output, but the order is arbitrary and they should be read by name not by number. FITS Header Units ================= HDU00 ----- HEALPixel keywords. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== =========================== ==== ============================================== KEY Example Value Type Comment ======== =========================== ==== ============================================== SPGRP healpix str Method of grouping spectra (always healpix for this file) SPGRPVAL 38863 int Healpix number HPXPIXEL 38863 int Healpix number HPXNSIDE 64 int Healpix nside HPXNEST True str Healpix nested? (vs. ring) SURVEY sv3 str DESI survey (sv1, sv3, main...) PROGRAM dark str DESI program (dark, bright, ...) CHECKSUM 96ZDB6YB96YBA6YB str HDU checksum updated 2021-07-20T01:03:03 DATASUM 0 str data unit checksum updated 2021-07-20T01:03:03 FIBERMIN -513 int INFIL000 spectra-sv1-dark-38863.fits str LONGSTRN OGIP 1.0 str ======== =========================== ==== ============================================== Empty HDU. HDU01 ----- EXTNAME = FIBERMAP Fibermap information combining the targeting photometry and metadata, and fiberassign requested positions. In the coadds, this HDU contains only the information that remains applicable to coadded spectra, e.g. the target flux values. Values that are only meaningful per-exposure (*e.g.* FIBER_X, FIBER_Y) are contained in the separate `EXP_FIBERMAP <#hdu02>`_ HDU. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 341 int Width of table in bytes NAXIS2 514 int Number of targets ENCODING ascii str LONGSTRN OGIP 1.0 str CHECKSUM 4aNU7WKR4aKR4UKR str HDU checksum updated 2021-07-20T01:03:03 DATASUM 4121667036 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Required Data Table Columns ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. rst-class:: columns ========================== ======= ============ =============================================================================================================================== Name Type Units Description ========================== ======= ============ =============================================================================================================================== TARGETID int64 Unique DESI target ID 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 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 REF_EPOCH float32 yr Reference epoch for Gaia/Tycho astrometry. Typically 2015.5 for Gaia 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) OBJTYPE char[3] Object type: TGT, SKY, NON, BAD SUBPRIORITY float64 Random subpriority [0-1) to break assignment ties OBSCONDITIONS int32 Bitmask of allowed observing conditions RELEASE int16 Imaging surveys release ID BRICKID int32 Brick ID from tractor input BRICK_OBJID int32 Imaging Surveys OBJID on that brick MORPHTYPE char[4] Imaging Surveys morphological type from Tractor 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) MASKBITS int16 Bitwise mask from the imaging indicating potential issue or blending 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 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 PARALLAX float32 mas Reference catalog parallax BRICKNAME char[8] Brick name from tractor input EBV float32 mag Galactic extinction E(B-V) reddening from SFD98 FLUX_W1 float32 nanomaggy WISE flux in W1 (AB) FLUX_W2 float32 nanomaggy WISE flux in W2 (AB) FLUX_IVAR_W1 float32 nanomaggy^-2 Inverse variance of FLUX_W1 (AB) FLUX_IVAR_W2 float32 nanomaggy^-2 Inverse variance of FLUX_W2 (AB) FIBERFLUX_G float32 nanomaggy Predicted g-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing FIBERFLUX_R float32 nanomaggy Predicted r-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing FIBERFLUX_Z float32 nanomaggy Predicted z-band flux within a fiber of diameter 1.5 arcsec from this object in 1 arcsec Gaussian seeing FIBERTOTFLUX_G float32 nanomaggy Predicted g-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing FIBERTOTFLUX_R float32 nanomaggy Predicted r-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing FIBERTOTFLUX_Z float32 nanomaggy Predicted z-band flux within a fiber of diameter 1.5 arcsec from all sources at this location in 1 arcsec Gaussian seeing SERSIC float32 Power-law index for the Sersic profile model (MORPHTYPE=”SER”) SHAPE_R float32 arcsec Half-light radius of galaxy model (>0) SHAPE_E1 float32 Ellipticity component 1 of galaxy model for galaxy type MORPHTYPE SHAPE_E2 float32 Ellipticity component 2 of galaxy model for galaxy type MORPHTYPE PHOTSYS char[1] 'N' for the MzLS/BASS photometric system, 'S' for DECaLS PRIORITY_INIT int64 Target initial priority from target selection bitmasks and OBSCONDITIONS NUMOBS_INIT int64 Initial number of observations for target calculated across target selection bitmasks and OBSCONDITIONS 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 DESI_TARGET int64 DESI (dark time program) target selection bitmask BGS_TARGET int64 BGS (Bright Galaxy Survey) target selection bitmask MWS_TARGET int64 Milky Way Survey targeting bits SCND_TARGET int64 Target selection bitmask for secondary programs 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 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 MEAN_DELTA_X float32 mm Mean (over exposures) fiber difference requested - actual CS5 X location on focal plane RMS_DELTA_X float32 mm RMS (over exposures) of the fiber difference between measured and requested CS5 X location on focal plane MEAN_DELTA_Y float32 mm Mean (over exposures) fiber difference requested - actual CS5 Y location on focal plane RMS_DELTA_Y float32 mm RMS (over exposures) of the fiber difference between measured and requested CS5 Y location on focal plane MEAN_FIBER_RA float64 deg Mean (over exposures) RA of actual fiber position STD_FIBER_RA float32 arcsec Standard deviation (over exposures) of RA of actual fiber position MEAN_FIBER_DEC float64 deg Mean (over exposures) DEC of actual fiber position STD_FIBER_DEC float32 arcsec Standard deviation (over exposures) of DEC of actual fiber position MEAN_PSF_TO_FIBER_SPECFLUX float32 Mean of input exposures fraction of light from point-like source captured by 1.5 arcsec diameter fiber given atmospheric seeing ========================== ======= ============ =============================================================================================================================== .. [1] Optional HDU02 ----- EXTNAME = EXP_FIBERMAP Fibermap entries that only apply to individual exposures, not to a coadd. This table has one row per input target per exposure. Also see the `FIBERMAP <#hdu01>`_ HDU for coadded fibermap quantities with one row per target. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 162 int Width of table in bytes NAXIS2 7112 int Number of input target-exposures ENCODING ascii str CHECKSUM g3Nmh2Nlg2Nlg2Nl str HDU checksum updated 2021-07-20T01:03:03 DATASUM 3607867694 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Required Data Table Columns ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. rst-class:: 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 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 ===================== ======= ======== ======================================================================================================= HDU03 ----- EXTNAME = B_WAVELENGTH Wavelength[nwave] array in Angstroms of b-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2751 int Number of wavelength bins BUNIT Angstrom str CHECKSUM 9FJDF9H99CHCC9H9 str HDU checksum updated 2021-07-20T01:03:03 DATASUM 979185614 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Data: FITS image [float64, 2751] HDU04 ----- EXTNAME = B_FLUX Flux[nspec,nwave] array in 1e-17 erg/(s cm2 Angstrom) of b-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ============================ ==== ============================================== KEY Example Value Type Comment ======== ============================ ==== ============================================== NAXIS1 2751 int Number of wavelength bins NAXIS2 514 int Number of spectra BUNIT 10**-17 erg/(s cm2 Angstrom) str CHECKSUM KdcnKccnKccnKccn str HDU checksum updated 2021-07-20T01:03:03 DATASUM 1454063034 str data unit checksum updated 2021-07-20T01:03:03 ======== ============================ ==== ============================================== Data: FITS image [float32, 2751x514] HDU05 ----- EXTNAME = B_IVAR Inverse variance of b-channel flux array Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================================= ==== ============================================== KEY Example Value Type Comment ======== ================================= ==== ============================================== NAXIS1 2751 int Number of wavelength bings NAXIS2 514 int Number of spectra BUNIT 10**+34 (s2 cm4 Angstrom2) / erg2 str CHECKSUM 1AE635E61AE613E6 str HDU checksum updated 2021-07-20T01:03:03 DATASUM 2902189966 str data unit checksum updated 2021-07-20T01:03:03 ======== ================================= ==== ============================================== Data: FITS image [float32, 2751x514] HDU06 ----- EXTNAME = B_MASK Mask[nspec,nwave] of b-channel flux array; 0=good. See the :doc:`bitmask documentation ` page for the definition of the bits. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2751 int Number of wavelength bins NAXIS2 514 int Number of spectra BSCALE 1 int BZERO 2147483648 int CHECKSUM 78fA97f677fA77f3 str HDU checksum updated 2021-07-20T01:03:03 DATASUM 707110 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Data: FITS image [int32, 2751x514] HDU07 ----- EXTNAME = B_RESOLUTION Resolution matrix stored as diagonals of a 3D sparse matrix. See the frame file :ref:`RESOLUTION documentation ` for how these are interpreted and used. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2751 int Number of wavelength bins NAXIS2 11 int Number of diagonals NAXIS3 514 int Number of spectra CHECKSUM 4q1B4o094o0A4o09 str HDU checksum updated 2021-07-20T01:03:03 DATASUM 1510900028 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Data: FITS image [float32, 2751x11x514] A sparse resolution matrix may be created for spectrum ``i`` with:: from desispec.resolution import Resolution R = Resolution(data[i]) Or using lower-level scipy.sparse matrices:: import scipy.sparse import numpy as np nspec, ndiag, nwave = data.shape offsets = ndiag//2 - np.arange(ndiag, dtype=int) R = scipy.sparse.dia_matrix((data[i], offsets), shape=(nwave, nwave)) HDU08 ----- EXTNAME = R_WAVELENGTH Wavelength[nwave] array in Angstroms of r-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2326 int Number of wavelength bins BUNIT Angstrom str CHECKSUM 9JTAFHQ79HQACHQ7 str HDU checksum updated 2021-07-20T01:03:03 DATASUM 456732359 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Data: FITS image [float64, 2326] HDU09 ----- EXTNAME = R_FLUX Flux[nspec,nwave] array in 1e-17 erg/(s cm2 Angstrom) of r-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ============================ ==== ============================================== KEY Example Value Type Comment ======== ============================ ==== ============================================== NAXIS1 2326 int Number of wavelength bins NAXIS2 514 int Number of spectra BUNIT 10**-17 erg/(s cm2 Angstrom) str CHECKSUM PCCbR99bPACbP99b str HDU checksum updated 2021-07-20T01:03:03 DATASUM 54356891 str data unit checksum updated 2021-07-20T01:03:03 ======== ============================ ==== ============================================== Data: FITS image [float32, 2326x514] HDU10 ----- EXTNAME = R_IVAR Inverse variance of the R_FLUX HDU. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================================= ==== ============================================== KEY Example Value Type Comment ======== ================================= ==== ============================================== NAXIS1 2326 int NAXIS2 514 int BUNIT 10**+34 (s2 cm4 Angstrom2) / erg2 str CHECKSUM GeBDGZ9DGbADGZ7D str HDU checksum updated 2021-07-20T01:03:03 DATASUM 789948970 str data unit checksum updated 2021-07-20T01:03:03 ======== ================================= ==== ============================================== Data: FITS image [float32, 2326x514] HDU11 ----- EXTNAME = R_MASK Mask[nspec,nwave] of r-channel flux array. 0==good. See the :doc:`bitmask documentation ` page for the definition of the bits. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2326 int Number of wavelengths NAXIS2 514 int Number of spectra BSCALE 1 int BZERO 2147483648 int CHECKSUM T5gdV3dcT3dcT3dc str HDU checksum updated 2021-07-20T01:03:03 DATASUM 598689 str data unit checksum updated 2021-07-20T01:03:03 ======== ================ ==== ============================================== Data: FITS image [int32, 2326x514] HDU12 ----- EXTNAME = R_RESOLUTION Diagonals of r-channel resolution matrix. See B_RESOLUTION HDU for description of the format. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2326 int Number of wavelengths NAXIS2 11 int Number of diagonals NAXIS3 514 int Number of spectra CHECKSUM DkAIDj3GDjAGDj3G str HDU checksum updated 2021-07-20T01:03:04 DATASUM 1927301622 str data unit checksum updated 2021-07-20T01:03:04 ======== ================ ==== ============================================== Data: FITS image [float32, 2326x11x514] HDU13 ----- EXTNAME = Z_WAVELENGTH Wavelength[nwave] array in Angstroms of z-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2881 int Number of wavelengths BUNIT Angstrom str CHECKSUM iaWMkYVMiaVMiYVM str HDU checksum updated 2021-07-20T01:03:04 DATASUM 3106662670 str data unit checksum updated 2021-07-20T01:03:04 ======== ================ ==== ============================================== Data: FITS image [float64, 2881] HDU14 ----- EXTNAME = Z_FLUX Flux[nspec,nwave] array in 1e-17 erg/(s cm2 Angstrom) of z-channel spectra Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ============================ ==== ============================================== KEY Example Value Type Comment ======== ============================ ==== ============================================== NAXIS1 2881 int Number of wavelengths NAXIS2 514 int Number of spectra BUNIT 10**-17 erg/(s cm2 Angstrom) str CHECKSUM 0aea1VdZ0Zda0ZdY str HDU checksum updated 2021-07-20T01:03:04 DATASUM 1889497861 str data unit checksum updated 2021-07-20T01:03:04 ======== ============================ ==== ============================================== Data: FITS image [float32, 2881x514] HDU15 ----- EXTNAME = Z_IVAR Inverse variance of z-channel flux array Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================================= ==== ============================================== KEY Example Value Type Comment ======== ================================= ==== ============================================== NAXIS1 2881 int Number of wavelengths NAXIS2 514 int Number of spectra BUNIT 10**+34 (s2 cm4 Angstrom2) / erg2 str CHECKSUM ni6Dpi3Cni3Cni3C str HDU checksum updated 2021-07-20T01:03:04 DATASUM 105099897 str data unit checksum updated 2021-07-20T01:03:04 ======== ================================= ==== ============================================== Data: FITS image [float32, 2881x514] HDU16 ----- EXTNAME = Z_MASK Mask[nspec,nwave] of z-channel flux array. 0==good. See the :doc:`bitmask documentation ` page for the definition of the bits. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2881 int Number of wavelengths NAXIS2 514 int Number of spectra BSCALE 1 int BZERO 2147483648 int CHECKSUM X6iYY4gYX4gYX4gY str HDU checksum updated 2021-07-20T01:03:04 DATASUM 740483 str data unit checksum updated 2021-07-20T01:03:04 ======== ================ ==== ============================================== Data: FITS image [int32, 2881x514] HDU17 ----- EXTNAME = Z_RESOLUTION Diagonals of z-channel resolution matrix. See B_RESOLUTION HDU for description of the format. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 2881 int Number of wavelengths NAXIS2 11 int Number of diagonals NAXIS3 514 int Number of spectra CHECKSUM oocZpnbYonbYonbY str HDU checksum updated 2021-07-20T01:03:04 DATASUM 1564215354 str data unit checksum updated 2021-07-20T01:03:04 ======== ================ ==== ============================================== Data: FITS image [float32, 2881x11x514] HDU18 ----- EXTNAME = SCORES Scores / metrics measured from the spectra for use in QA and systematics studies. These are coadded from the input :doc:`cframe SCORES HDU ` files. Required Header Keywords ~~~~~~~~~~~~~~~~~~~~~~~~ .. collapse:: Required Header Keywords Table .. rst-class:: keywords ======== ================ ==== ============================================== KEY Example Value Type Comment ======== ================ ==== ============================================== NAXIS1 172 int Width of table in bytes NAXIS2 514 int Number of spectra ENCODING ascii str CHECKSUM XQAAZP89XPAAXP79 str HDU checksum updated 2021-07-20T01:03:05 DATASUM 3357773203 str data unit checksum updated 2021-07-20T01:03:05 ======== ================ ==== ============================================== Required Data Table Columns ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. rst-class:: columns =================== ======= ===== ============================================================ Name Type Units Description =================== ======= ===== ============================================================ TARGETID int64 Unique DESI target ID INTEG_COADD_FLUX_B float32 integ. flux in wave. range 4000,5800A MEDIAN_COADD_FLUX_B float32 median flux in wave. range 4000,5800A MEDIAN_COADD_SNR_B float32 median SNR/sqrt(A) in wave. range 4000,5800A INTEG_COADD_FLUX_R float32 integ. flux in wave. range 5800,7600A MEDIAN_COADD_FLUX_R float32 median flux in wave. range 5800,7600A MEDIAN_COADD_SNR_R float32 median SNR/sqrt(A) in wave. range 5800,7600A INTEG_COADD_FLUX_Z float32 integ. flux in wave. range 7600,9800A MEDIAN_COADD_FLUX_Z float32 median flux in wave. range 7600,9800A MEDIAN_COADD_SNR_Z float32 median SNR/sqrt(A) in wave. range 7600,9800A TSNR2_GPBDARK_B float32 template (S/N)^2 for dark targets in guider pass band on B TSNR2_ELG_B float32 ELG B template (S/N)^2 TSNR2_GPBBRIGHT_B float32 template (S/N)^2 for bright targets in guider pass band on B TSNR2_LYA_B float32 LYA B template (S/N)^2 TSNR2_BGS_B float32 BGS B template (S/N)^2 TSNR2_GPBBACKUP_B float32 GPBBACKUP B template (S/N)^2 TSNR2_QSO_B float32 QSO B template (S/N)^2 TSNR2_LRG_B float32 LRG B template (S/N)^2 TSNR2_GPBDARK_R float32 template (S/N)^2 for dark targets in guider pass band on R TSNR2_ELG_R float32 ELG R template (S/N)^2 TSNR2_GPBBRIGHT_R float32 template (S/N)^2 for bright targets in guider pass band on R TSNR2_LYA_R float32 LYA R template (S/N)^2 TSNR2_BGS_R float32 BGS R template (S/N)^2 TSNR2_GPBBACKUP_R float32 GPBBACKUP R template (S/N)^2 TSNR2_QSO_R float32 QSO R template (S/N)^2 TSNR2_LRG_R float32 LRG R template (S/N)^2 TSNR2_GPBDARK_Z float32 template (S/N)^2 for dark targets in guider pass band on Z TSNR2_ELG_Z float32 ELG Z template (S/N)^2 TSNR2_GPBBRIGHT_Z float32 template (S/N)^2 for bright targets in guider pass band on Z TSNR2_LYA_Z float32 LYA Z template (S/N)^2 TSNR2_BGS_Z float32 BGS Z template (S/N)^2 TSNR2_GPBBACKUP_Z float32 GPBBACKUP Z template (S/N)^2 TSNR2_QSO_Z float32 QSO Z template (S/N)^2 TSNR2_LRG_Z float32 LRG Z template (S/N)^2 TSNR2_GPBDARK float32 template (S/N)^2 for dark targets in guider pass band TSNR2_ELG float32 ELG template (S/N)^2 summed over B,R,Z TSNR2_GPBBRIGHT float32 template (S/N)^2 for bright targets in guider pass band TSNR2_LYA float32 LYA template (S/N)^2 summed over B,R,Z TSNR2_BGS float32 BGS template (S/N)^2 summed over B,R,Z TSNR2_GPBBACKUP float32 GPBBACKUP template (S/N)^2 summed over B,R,Z TSNR2_QSO float32 QSO template (S/N)^2 summed over B,R,Z TSNR2_LRG float32 LRG template (S/N)^2 summed over B,R,Z =================== ======= ===== ============================================================ Notes and Examples ================== Coadd files can be read and interpreted using the same code examples shown in the "Notes and Examples" section of the :doc:`spectra files ` documentation. The format supports arbitrary channel (camera) names as long as for each channel {X} there is a set of HDUs named {X}_WAVELENGTH, {X}_FLUX, {X}_IVAR, {X}_MASK, {X}_RESOLUTION. 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 :doc:`fiberassign ` design step; thus the following columns can have different values than in the :doc:`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``).