General description: This file contains information about flux density, wavelength solution, fibermask and line width obtained from extracted arc calibration frames. This file is generated as a product of spcalib.pro.
Naming convention: Filenames have the form spArc-[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 spArc-r2-00111704.fits.gz.
Approximate size: 6.6Mb.
File type: FITS
Read by products: spreduce.pro,
Written by products: spCalib.pro
The data attribute of Primary HDU stores the extracted flux for the entire image.
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 = 4112 / NAXIS2 = 500 / EXTEND = T / TELESCOP= 'SDSS 2.5-M' / Sloan Digital Sky Survey FILENAME= 'sdR-b1-00132655.fit' CAMERAS = 'b1 ' / EXPOSURE= 132655 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 = 'arc ' / exposure type, SDSS spectro style BOSSVER = '2 ' / ICC version MJD = 55744 / APO fMJD day at start of exposure TAI-BEG = 4816296943.999999 / MJD(TAI) seconds at start of integration DATE-OBS= '2011-07-02T04:15:44' / 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 = 46.118 / Azimuth axis pos. (approx, deg) ALT = 83.342 / Altitude axis pos. (approx, deg) IPA = 223.253 / Rotator axis pos. (approx, deg) SPA = 42.47535252178478 / TCC SpiderInstAng FOCUS = 0.0 / User-specified focus offset (um) M2PISTON= 1115.98 / TCC SecOrient M2XTILT = -9.0 / TCC SecOrient M2YTILT = -4.02 / TCC SecOrient M2XTRAN = -58.23 / TCC SecOrient M2YTRAN = -285.15 / TCC SecOrient M1PISTON= 0.0 / TCC PrimOrient M1XTILT = -13.67 / TCC PrimOrient M1YTILT = 10.53 / TCC PrimOrient M1XTRAN = 574.8 / TCC PrimOrient M1YTRAN = 742.37 / TCC PrimOrient SCALE = 1.0 / User-specified scale factor PRESSURE= 21.614 / pressure WINDD = 111.6 / windd WINDS = 17.0 / winds GUSTD = 111.1 / gustd GUSTS = 22.5 / gusts AIRTEMP = 16.8 / airTempPT DEWPOINT= 5.8 / dpTempPT DPERRPT = 'NaN ' / failed to fetch dpErrPT HUMIDITY= 50.6 / humidity DUSTA = 42384.0 / dusta DUSTB = 2494.0 / dustb WINDD25M= 172.5 / windd25m WINDS25M= 18.8 / winds25m FF = '0 0 0 0 ' / FF lamps 1:on 0:0ff NE = '1 1 1 1 ' / NE lamps 1:on 0:0ff HGCD = '1 1 1 1 ' / HGCD lamps 1:on 0:0ff FFS = '1 1 1 1 1 1 1 1' / Flatfield Screen 1:closed 0:open GUIDER1 = 'proc-gimg-0397.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-0397.fits' / The last guider image COLLA = 35819 / The position of the A collimator motor COLLB = 35907 / The position of the B collimator motor COLLC = 35808 / The position of the C collimator motor HARTMANN= 'Out ' / Hartmanns: Left,Right,Out MC1HUMHT= 17.6 / sp1 mech Hartmann humidity, % MC1HUMCO= 11.8 / sp1 mech Central optics humidity, % MC1TEMDN= 15.6 / sp1 mech Median temp, C MC1THT = 15.5 / sp1 mech Hartmann Top Temp, C MC1TRCB = 15.6 / sp1 mech Red Cam Bottom Temp, C MC1TRCT = 16.2 / sp1 mech Red Cam Top Temp, C MC1TBCB = 15.5 / sp1 mech Blue Cam Bottom Temp, C MC1TBCT = 15.9 / sp1 mech Blue Cam Top Temp, C REQTIME = 4.0 / requested exposure time EXPTIME = 4.82 / measured exposure time, s SHOPETIM= 0.72 / open shutter transit time, s SHCLOTIM= 0.54 / close shutter transit time, s DARKTIME= 22.40277194976807 / time between flush end and readout start CAMROW = 0 / CAMCOL = 1 / 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= F / Extra 1/3 row in wavecal at array center? QUALITY = 'excellent' / RDNOISE0= 2.01088 /CCD read noise amp 0 [electrons] RDNOISE1= 1.92738 /CCD read noise amp 1 [electrons] RDNOISE2= 1.88853 /CCD read noise amp 2 [electrons] RDNOISE3= 1.85922 /CCD read noise amp 3 [electrons] PIXFLAT = 'pixflatave-55415-b1.fits.gz' / BADPIXEL= 'badpixels-55415-b1.fits.gz' / FBADPIX = 2.91520E-05 /Fraction of bad pixels in raw image BESTCORR= 0.741287 /Best Correlation coefficient
The data attribute of HDU 1 stores the wavelengths of good lamp lines (in Angstroms) and the Y position of each fiber on the CCD for the corresponding wavelengths. The data in HDU 1 is of size 65 X 501 in which the first of the 501 columns stores the wavelengths of the good lamp lines, and the remaining 500 columns store the Y positions of those lines for each of the 500 fibers.
Required header keywords:
XTENSION= 'IMAGE ' /Image Extension created by MWRFITS v1.8 BITPIX = -64 / array data type NAXIS = 2 / number of array dimensions
Optional header keywords:
NAXIS1 = 501 / length of dimension 2 NAXIS2 = 65 / length of dimension 2 PCOUNT = 0 / Normally 0 (no varying arrays) GCOUNT = 1 / number of groups
The HDU 2 data is a binary table whose fields are used to calculate wavelength solution (units of log10 Angstroms) for the arc calibration frames. The Y-positions on the CCD, which is the independent variable and corresponding wavelength solutions (in Angstroms) 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 (string) = 'BINTABLE'/Binary table written by MWRFITS v1.8 BITPIX = 8 /array data type NAXIS = 2 /number of array dimensions
Optional header keywords:
NAXIS1 = 24024 /Number of bytes per row NAXIS2 = 1 /Number of rows PCOUNT = 0 /Normally 0 (no varying arrays) GCOUNT = 1 /number of groups TFIELDS = 4 /Number of columns in table
Required column names:
FUNC (string) : describes the function used to fit the wavelength solutions (units of log-10 Angstroms) and Y-positions to a functional form.
Chebyshev or Legendre 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 wavelength solution.
XMIN (float64) : minimum value of the independent variable used by fitting function.
COEFF [3000](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 / array data type NAXIS = 1 / number of array dimensions
Optional header keywords:
NAXIS1 = 500 / length of dimension 1 PCOUNT = 0 / Normally 0 (no varying arrays) GCOUNT = 1 / number of groups
The data attribute of HDU 4 gives the line width (in the dispersion axis) for each fiber. This Gaussian sigma is in units of pixels. The Y-positions on the CCD, which is the independent variable and the corresponding line width, which is the dependent variable are fitted to a functional form and the resulting coefficients are stored in a binary table.
Required header keywords:
XTENSION= 'BINTABLE' /Binary table written by MWRFITS v1.8 BITPIX = 8 /Required value NAXIS = 2 /Required value
Optional header keywords:
NAXIS1 = 24024 /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) : describes the function used to fit the line width (units of pixels) and Y-positions to a functional form.
Chebyshev or Legendre 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 line width of fibers.
XMIN (float64) : minimum value of the independent variable used by fitting function.