General description: This file contains information about fiberflats, X-centers of fibers, fibermask, profile width and superflat obtained from extracted flat calibration frames. This file is generated as a product of spcalib.pro.
Naming convention: Filenames have the form spFlat-[c][n]-mmmmmmmm.fits.gz, where c indicates either a blue or red spectrograph, n indicates the spectrograph number (1 or 2) and mmmmmmmm indicates the frame number. An example of filename is spFlat-r2-00111703.fits.gz.
Approximate size: 8.0 Mb.
File type: FITS
Read by products: spreduce.pro
Written by products: spCalib.pro
The primary HDU data is an array of flat-field vectors for each fiber that removes relative flat-field variations as a function of wavelength between fibers. These are referred as fiberflats.
Required header keywords:
SIMPLE = T / conforms to FITS standard BITPIX = -32 / array data type NAXIS = 2 / number of array dimensions
Optional header keywords:
SIMPLE = T / conforms to FITS standard BITPIX = -32 / array data type NAXIS = 2 / number of array dimensions NAXIS1 = 4128 / NAXIS2 = 500 / EXTEND = T / TELESCOP= 'SDSS 2.5-M' / Sloan Digital Sky Survey FILENAME= 'sdR-r1-00132532.fit' CAMERAS = 'r1 ' / EXPOSURE= 132532 DAQVER = '1.3.1 ' CAMDAQ = '1.5.0:37' SUBFRAME= '' / the subframe readout command ERRCNT = 'NONE ' SYNCERR = 'NONE ' SLINES = 'NONE ' PIXERR = 'NONE ' PLINES = 'NONE ' PFERR = 'NONE ' DIDFLUSH= T / CCD was flushed before integration FLAVOR = 'flat ' / exposure type, SDSS spectro style BOSSVER = '2 ' / ICC version MJD = 55742 / APO fMJD day at start of exposure TAI-BEG = 4816131116.000001 / MJD(TAI) seconds at start of integration DATE-OBS= '2011-06-30T06:11:56' / TAI date at start of integration NAME = '5008-55742-01' / The name of the currently loaded plate PLATEID = 5008 / The currently loaded plate CARTID = 15 / The currently loaded cartridge MAPID = 1 / The mapping version of the loaded plate POINTING= 'A ' / The currently specified pointing OBJSYS = 'ICRS ' / The TCC objSys RA = 243.1337 / RA of telescope boresight (deg) DEC = 28.0649 / Dec of telescope boresight (deg) RADEG = 243.1337 / RA of telescope pointing(deg) DECDEG = 28.0649 / Dec of telescope pointing (deg) ROTTYPE = 'Obj ' / Rotator request type ROTPOS = 0.0 / Rotator request position (deg) BOREOFFX= 0.0 / TCC Boresight offset, deg BOREOFFY= 0.0 / TCC Boresight offset, deg ARCOFFX = 0.0 / TCC ObjArcOff, deg ARCOFFY = 0.0 / TCC ObjArcOff, deg OBJOFFX = 0.0 / TCC ObjOff, deg OBJOFFY = 0.0 / TCC ObjOff, deg CALOFFX = -0.003 / TCC CalibOff, deg CALOFFY = 0.006 / TCC CalibOff, deg CALOFFR = 0.0 / TCC CalibOff, deg GUIDOFFX= 0.0 / TCC GuideOff, deg GUIDOFFY= 0.0 / TCC GuideOff, deg GUIDOFFR= 0.0 / TCC GuideOff, deg AZ = 278.467 / Azimuth axis pos. (approx, deg) ALT = 70.742 / Altitude axis pos. (approx, deg) IPA = 109.488 / Rotator axis pos. (approx, deg) SPA = -70.53251248264694 / TCC SpiderInstAng FOCUS = 391.91 / User-specified focus offset (um) M2PISTON= -1481.2 / TCC SecOrient M2XTILT = -8.949999999999999 / TCC SecOrient M2YTILT = -3.99 / TCC SecOrient M2XTRAN = -58.11 / TCC SecOrient M2YTRAN = -198.09 / TCC SecOrient M1PISTON= -3628.31 / TCC PrimOrient M1XTILT = -13.67 / TCC PrimOrient M1YTILT = 10.53 / TCC PrimOrient M1XTRAN = 574.51 / TCC PrimOrient M1YTRAN = 742.37 / TCC PrimOrient SCALE = 1.000367 / User-specified scale factor PRESSURE= 21.616 / pressure WINDD = 126.8 / windd WINDS = 18.7 / winds GUSTD = 127.2 / gustd GUSTS = 26.5 / gusts AIRTEMP = 16.9 / airTempPT DEWPOINT= 3.3 / dpTempPT DPERRPT = 'NaN ' / failed to fetch dpErrPT HUMIDITY= 41.7 / humidity DUSTA = 35571.0 / dusta DUSTB = 2504.0 / dustb WINDD25M= 180.4 / windd25m WINDS25M= 12.9 / winds25m FF = '1 1 1 1 ' / FF lamps 1:on 0:0ff NE = '0 0 0 0 ' / NE lamps 1:on 0:0ff HGCD = '0 0 0 0 ' / HGCD lamps 1:on 0:0ff FFS = '1 1 1 1 1 1 1 1' / Flatfield Screen 1:closed 0:open GUIDER1 = 'proc-gimg-0374.fits' / The first guider image SLITID1 = 15 / Normalized slithead ID. sp1&2 should match. SLITID2 = 15 / Normalized slithead ID. sp1&2 should match. GUIDERN = 'proc-gimg-0374.fits' / The last guider image COLLA = 36540 / The position of the A collimator motor COLLB = 36628 / The position of the B collimator motor COLLC = 36531 / The position of the C collimator motor HARTMANN= 'Out ' / Hartmanns: Left,Right,Out MC1HUMHT= 28.6 / sp1 mech Hartmann humidity, % MC1HUMCO= 18.0 / sp1 mech Central optics humidity, % MC1TEMDN= 15.2 / sp1 mech Median temp, C MC1THT = 15.2 / sp1 mech Hartmann Top Temp, C MC1TRCB = 15.0 / sp1 mech Red Cam Bottom Temp, C MC1TRCT = 15.7 / sp1 mech Red Cam Top Temp, C MC1TBCB = 15.0 / sp1 mech Blue Cam Bottom Temp, C MC1TBCT = 15.3 / sp1 mech Blue Cam Top Temp, C REQTIME = 30.0 / requested exposure time EXPTIME = 30.82 / measured exposure time, s SHOPETIM= 0.72 / open shutter transit time, s SHCLOTIM= 0.54 / close shutter transit time, s DARKTIME= 42.49553894996643 / time between flush end and readout start CAMROW = 0 / CAMCOL = 4 / AUTHOR = 'Scott Burles & David Schlegel' / VERSIDL = '7.0 ' / Version of IDL VERSUTIL= 'v5_4_24 ' / Version of idlutils VERSREAD= 'v5_4_45 ' / Version of idlspec2d for pre-processing raw dat VERSLOG = 'trunk 126283' / Version of SPECLOG product VERSFLAT= 'v1_16 ' / Version of SPECFLAT product TWOPHASE= T / Extra 1/3 row in wavecal at array center? QUALITY = 'excellent' / RDNOISE0= 2.75311 /CCD read noise amp 0 [electrons] RDNOISE1= 2.64738 /CCD read noise amp 1 [electrons] RDNOISE2= 2.45013 /CCD read noise amp 2 [electrons] RDNOISE3= 2.51683 /CCD read noise amp 3 [electrons] PIXFLAT = 'pixflatave-55415-r1.fits.gz' / BADPIXEL= 'badpixels-55415-r1.fits.gz' / NBRIGHT = 6 /Number of bright pixels (>10^5) in extracted fla
The HDU 1 data is a binary table whose fields are used to calculate the X-centers, for all fibers in the flat-field calibration frames. The Y-pixel positions on the CCD, which is the independent variable and the corresponding X-centers, which is the dependent variable are fitted to a functional form and the resulting coefficients are stored in the binary table.
Required header keywords:
XTENSION= 'BINTABLE' /Binary table written by MWRFITS v1.8 BITPIX = 8 /Required value NAXIS = 2 /Required value NAXIS1 = 16024 /Number of bytes per row NAXIS2 = 1 /Number of rows PCOUNT = 0 /Normally 0 (no varying arrays) GCOUNT = 1 /Required value TFIELDS = 4 /Number of columns in table
Required column names:
FUNC (string) :function used to fit the Y-pixel positions on the CCD and corresponding X-centers are fitted to a functional form.
Polynomial, Chebyshev, Legendre or Chebyshev_split functions are used. Default value is taken as Legendre function
XMAX (float64) : maximum value of the independent variable which is used along with the fitting coefficients, in the fitting function to get the value of dependent variable, which is the X-center of fibers.
XMIN (float64) : minimum value of the independent variable used by fitting function.
COEFF [2000](float64) : fit coefficents
The HDU 3 data stores the fibermask. These are fiber status bits and are set to non-zero to indicate bad status. The status bits used for masking are documented in $IDLUTILS/v5_4_12/data/sdss/sdssMaskbits.par.
Required header keywords:
XTENSION= 'IMAGE' /Image Extension created by MWRFITS v1.8 BITPIX = 32 / NAXIS = 1 /
Optional header keywords:
NAXIS1 = 500 / PCOUNT = 0 / GCOUNT = 1 /
The data attribute of HDU 3 gives the first-order corrected profile width for each fiber bundle. This Gaussian sigma is in units of pixels. The X-positions on the CCD and their corresponding profile width are fitted to a functional form and the resulting coefficients are stored in a binary table. The X-position is the independent variable and the width is the dependent variable for the fitting function.
Required header keywords:
XTENSION= 'BINTABLE' /Binary table written by MWRFITS v1.8 BITPIX = 8 /Required value NAXIS = 2 /Required value NAXIS1 = 12024 /Number of bytes per row NAXIS2 = 1 /Number of rows PCOUNT = 0 /Normally 0 (no varying arrays) GCOUNT = 1 /Required value TFIELDS = 4 /Number of columns in table
Required column names:
FUNC (string) :function used to fit the X-positions on CCD and the correspoding profile widths to a functional form.
Polynomial, Chebyshev, Legendre or Chebyshev_split functions are used. Default value is taken as Legendre function.
XMAX (float64) : maximum value of the independent variable which is used along with the fitting coefficients, in the fitting function to get the value of dependent variable, which is the profile width of fibers.
XMIN (float64) : minimum value of the independent variable used by fitting function.
COEFF [1500](float64) : fit coefficents
The data attribute of HDU 4 contains superflat which is constructed from extracted flat-field image and is stored in a bspline set structure form. A superflat is a bspline average across all fibers of the flat spectrum in raw counts as a function of wavelength. The various column name are explained in the b-spline routine in $IDLUTILS/pro/bspline
Required header keywords:
XTENSION= 'BINTABLE' /Binary table written by MWRFITS v1.8 BITPIX = 8 /Required value NAXIS = 2 /Required value NAXIS1 = 38948 /Number of bytes per row NAXIS2 = 1 /Number of rows PCOUNT = 0 /Normally 0 (no varying arrays) GCOUNT = 1 /Required value TFIELDS = 5 /Number of columns in table
Required column names:
FULLBKPT[float] BKMASK [short int] NORD [float] COEFF [1000][float] ICOEFF [float]