Frame Gang File

File Format: FITS binary table

Name: idGang-rrrrrr-c#-ffff.fit for photometric columns, and idGang-rrrrrr-r#-ffff.fit for astrometric rows, where rrrrrr is the imaging run number, # is the photometric column or astrometric row in the Imaging Array, and ffff is the frame number.

Produced by: iop

Used by: iop (quality analysis), ssc

Size: 480.96 Kb for photometric gang files and 1,128.96 Kb for astrometric gang files. Total for all chips for a 1000 frame/chip run is 7,401.6 Mb.

Archived? Yes. Tracked file.

Description

A frame gang file groups information created by the DA system for a single set of frames from a single DA CPU: i.e., for either a single column of photometric CCDs or a single row of astrometric CCDs.

Primary Header


SIMPLE  =                    F
BITPIX  =                    8
NAXIS   =                    0
EXTEND  =                    T
SDSS                           / special flag for decoding simple=f data
UNSIGNED                       / U format used - unsigned 16 bit data in table
BZERO   = 3.27680000000000E+04                                                  
BSCALE  = 1.00000000000000E+00                                                  
TAI     =        XXXXXXXXXX.XX / Number of seconds since Nov 17 1858 0 UT/TAI.
RA      =           XXX.XXXXXX / Right ascension/longitude. (degrees)
DEC     =           XXX.XXXXXX / Declination/latitude. (degrees)
SPA     =              XXX.XXX / Camera col position angle wrt north. (degrees)
IPA     =              XXX.XXX / Instrument rotator position angle. (degrees)
IPARATE =             XXX.XXXX / Instrument rotator angular velocity. (deg/sec)
AZ      =           XXX.XXXXXX / Azimuth (encoder) of telescope. (degrees)
ALT     =           XXX.XXXXXX / Altitude (encoder) of telescope. (degrees)
FOCUS   =                XXX.X / Focus position (encoder). (microns)
DATE-OBS= 'DD/MM/YY'           / TAI date (DD/MM/YY)
TAIHMS  = 'HH:MM:SS.SS'        / TAI time (HH:MM:SS.SS) (TAI-UT = approx 30 s)
DAVERS  = 'XXX     '           / Version of DA software
BADLINES=                    0 / Number of bad lines in frame                   
FRAME   =                  XXX / Frame number.
RUN     =                  XXX / Imaging run number.
BUNITS  = 'ADUs    '                                                            
ORIGIN  = 'SDSS    '
TELESCOP= '2.5m    '
CCDMODE = 'XXX     '           / 'STARING' or 'DRIFT'
EQUINOX =              XXXX.XX / Equinox of the TCC coordinates.
SYSTEM  = 'XXX     '           / System of the TCC coordinates (mean, apparent).
CAMCOL  =                  XXX / Column in the imaging camera. (astro chips only)
CCDSECL = '[1:2128,1:1361]'
OVERSECL= '[1:20,1:1361]'
BIASSECL= '[21:40,1:1361]'
DATASECL= '[41:2088,1:1361]'
CCDSECR = '[0:0,0:0]'
DATASECR= '[0:0,0:0]'
BIASSECR= '[0:0,0:0]'
OVERSECR= '[1:20,1:1361]'
C_OBS   =                XXX.X / CCD row clock rate. (usec/row)
COLBIN  =                  XXX / Binning factor perpendicular to the columns.
ROWBIN  =                  XXX / Binning factor perpendicular to the rows.
NLINES  =                 1361 / Number of lines in a frame                     
AMPL    =                    1
AMPR    =                    1
OBSERVER= 'XXX     '
FLAVOR  = 'XXX     '           / Flavor of this run (science, calibration, test,
SYS_SCN = 'XXX     '           / Coordinate system of the scan great circle.
EQNX_SCN=              XXXX.XX / Equinox of the scan great circle. (years)
NODE    =            XXX.XXXXX / Ra of the great circle's ascending node. (deg)
INCL    =            XXX.XXXXX / Great circle's inclination wrt cel eq. (deg)
XBORE   =                XXX.X / Boresight x offset from the array center. (mm)
YBORE   =                XXX.X / Boresight y offset from the array center. (mm)
STRIP   = 'XXX     '           / Strip in the stripe being tracked (N or S).
STRIPE  =                  XXX / Survey stripe identifier.
FIELD   =                  XXX / Field sequence number within the run           
OBJECT  = 'XXX     '           / e.g., 'stripe 50.6 degrees, north strip'
EXPTIME =               XXX.XX / Exposure time (seconds)
END

Quartiles Header

HDU's of this format are found in photometric gang files only. There are 5 of these HDUs, one per CCD in the column. Below, NAXIS2 will be equal to 2128. The TSHIFT keyword gives the amount by which each quartile value has been multiplied; e.g., if TSHIFT = 100, then each quartile value in the HDU is 100 times larger than the true value. This scaling allows us to calculate precise quartile values while maintaining pure integers. In EXTNAME, "LOC" is replaced with the two digit identifier for the location of the CCD in the imaging camera.

[an error occurred while processing this directive]

XTENSION= 'BINTABLE'          
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                   12
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                    3
[an error occurred while processing this directive]
EXTNAME = 'QUART LOC'
CAMROW  =                  XXX / Row in imaging camera
TSHIFT  =                  XXX / Quartile scaling factor
HISTBINS=                  XXX / Num bins in quartile hists
DBASE   =                  XXX / Maximum delta for hist bases
NQCALCL =                  XXX / Number of quartiles calculated - lo col numbers
NQCALCR =                  XXX / Number of quartiles calculated - hi col numbers
FRBIASL =                  XXX / Left  Frame bias x TSHIFT
FRBIASR =                  XXX / Right Frame bias x TSHIFT
FRSKYL  =                  XXX / Left Mean Sky Value x TSHIFT
FRSKYR  =                  XXX / Right Mean Sky Value x TSHIFT
FROSCNL =                  XXX / Left Mean Oscn Value x TSHIFT
FROSCNR =                  XXX / Right Mean Oscn Value x TSHIFT
SKIPPED =                  XXX / Number of rows ignored
QTNCUT  =                  XXX / SigCut = qtNcut * 0.00527 * sigma              
AUTHOR  = 'Node=sdssid1.fnal.gov Type=photo Cr=1 Bd=0 #=5 Src=CAMERA'
[an error occurred while processing this directive]
TFORM1  = '1J      '          
TTYPE1  = 'q1      '           / 25th percentile.
TUNIT1  = 'ADUs x TSHIFT'     
TFORM2  = '1J      '          
TTYPE2  = 'q2      '           / 50th percentile.
TUNIT2  = 'ADUs x TSHIFT'     
TFORM3  = '1J      '          
TTYPE3  = 'q3      '           / 75th percentile.
TUNIT3  = 'ADUs x TSHIFT'     
[an error occurred while processing this directive]
END

Postage Stamp Header

There is one HDU of this format for each CCD (including focus CCDs) handled by the DA CPU (e.g., 6 for astrometric rows, and 5 for photometric columns). Note that every HDU of this format contains an exact number of rows in its binary table (30 for photometric HDUs, 100 for astrometric HDUs), but not every row contains real data around a star. The keyword BSCOUNT specifies the actual number of stars detected; the rows after the first BSCOUNT rows should be ignored. This is done for speed purposes in the DA system. Thus, NAXIS2 is always equal to 30 for photometric HDUs, and 100 for astrometric HDUs. In EXTNAME, "LOC" is replaced with the two digit identifier for the location of the CCD in the imaging camera.

XTENSION= 'BINTABLE'
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                 1686
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                    3
EXTNAME = 'STAMP LOC'
CAMROW  =                  XXX / Row in imaging camera (PHOTO CHIPS ONLY)
PSSIZE  =                   29 / Postage Stamp Size
BSCOUNT =                  XXX / Number of Bright Stars
PIX4STAR=                  XXX / Number of pixels in 3x3 needed for star
STAR5X5 =                  XXX / True means use 5x5 for star finding
STARDIST=                  XXX / Minimum distance between adjacent stars
SDISTRIB=                  XXX / True means distribute stamps over frame
STHRESHL=                  XXX / Star threshold - lo column numbers
STHRESHR=                  XXX / Star threshold - hi column numbers
SABSKYL =                  XXX / Value to add to sky level = threshold - lo colu
SABSKYR =                  XXX / Value to add to sky level = threshold - hi colu
SSATL   =                  XXX / Star saturation - lo column numbers
SSATR   =                  XXX / Star saturation - hi column numbers
SLOCOLL =                  XXX / Number of lo cols to skip for lo column numbers
SLOCOLR =                  XXX / Number of lo cols to skip for hi column numbers
SHICOLL =                  XXX / Number of hi cols to skip for lo column numbers
SHICOLR =                  XXX / Number of hi cols to skip for hi column numbers
TSHIFT  =                  XXX / Bias scaling factor
FRBIASL =                  XXX / Left  Frame bias x TSHIFT
FRBIASR =                  XXX / Right Frame bias x TSHIFT
FRSKYL  =                  XXX / Left Mean Sky Value x TSHIFT
FRSKYR  =                  XXX / Right Mean Sky Value x TSHIFT
FROSCNL =                  XXX / Left Mean Oscn Value x TSHIFT
FROSCNR =                  XXX / Right Mean Oscn Value x TSHIFT
SKIPPED =                  XXX / Number of rows ignored
TIMEROW =                  XXX / 10*Average time per row (usec)
TIMEFRAM=                  XXX / 10*Time to analyze PREVIOUS frame (usec), scale
AUTHOR  = 'Node=sdssid1.fnal.gov Type=photo Cr=1 Bd=0 #=5 Src=CAMERA'
TFORM1  = '841U    '           / PostStamp ushorts
TTYPE1  = 'pixelMap'           / Postage Stamp subimage
TUNIT1  = 'ADUs    '
TFORM2  = '1I      '
TTYPE2  = 'midRow  '           / Frame row (data section) of middle pixel
TFORM3  = '1I      '
TTYPE3  = 'midCol  '           / Frame column (data section) of middle pixel
END

Bright Star Measured Parameters Header

There is one HDU of this format for each CCD (including focus CCDs) handled by the DA CPU (e.g., 6 for astrometric rows, and 5 for photometric columns). Note that every HDU of this format contains an exact number of rows in its binary table (30 for photometric HDUs, 100 for astrometric HDUs), but not every row contains real data around a star. The keyword BSCOUNT specifies the actual number of stars detected; the rows after the first BSCOUNT rows should be ignored. This is done for speed purposes in the DA system. Thus, NAXIS2 is always equal to 30 for photometric HDUs, and 100 for astrometric HDUs. In EXTNAME, "LOC" is replaced with the two digit identifier for the location of the CCD in the imaging camera.

The table fields given below are for photometric and astrometric chips. Data from the focus chips are stored in the same fields, but with different meanings. For the focus chips, the fields have the following meanings:


[an error occurred while processing this directive]

XTENSION= 'BINTABLE'          
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                   48
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                   12
[an error occurred while processing this directive]
EXTNAME = 'STAR LOC'
CAMROW  =                  XXX / Row in imaging camera (PHOTO CHIPS ONLY)
BSCOUNT =                  XXX / Number of Bright Stars
FOCFLAG =                  XXX / Focus code run flag
SIGFILT =             X.XXXXXX / Sigma used for gunn filter
VARFILTL=             X.XXXXXX / Variance (left)  used for gunn filter
VARFILTR=             X.XXXXXX / Variance (right) used for gunn filter
GAINFILL=             X.XXXXXX / Amp Gain (left)  used for gunn filter
GAINFILR=             X.XXXXXX / Amp Gain (right) used for gunn filter
NMEDIAN =                  XXX / Number used in stokes medians
RMEDIAN =                  XXX / Median of rmajor for Stars
QMEDIAN =                  XXX / Median of Q for Stars
UMEDIAN =                  XXX / Median of U for Stars
AUTHOR  = 'Node=sdssid1.fnal.gov Type=photo Cr=1 Bd=0 #=5 Src=CAMERA'
[an error occurred while processing this directive]
TFORM1  = '1J      '          
TTYPE1  = 'midRow  '           / Frame row of the stamp's middle pixel.
TFORM2  = '1J      '          
TTYPE2  = 'midCol  '           / Frame column of the stamp's middle pixel.
TFORM3  = '1E      '          
TTYPE3  = 'rowCentroid'        / Row position of star center.
TUNIT3  = 'pixels  '          
TFORM4  = '1E      '          
TTYPE4  = 'rowCentroidErr'     / Row position of star center. (error)
TUNIT4  = 'pixels  '          
TFORM5  = '1E      '          
TTYPE5  = 'colCentroid'        / Column position of star center.
TUNIT5  = 'pixels  '          
TFORM6  = '1E      '          
TTYPE6  = 'colCentroidErr'     / Column position of star center. (error)
TUNIT6  = 'pixels  '          
TFORM7  = '1E      '          
TTYPE7  = 'rMajor  '           / Major axis radius. 
TUNIT7  = 'pixels  '          
TFORM8  = '1E      '          
TTYPE8  = 'rMinor  '           / Minor axis radius.
TUNIT8  = 'pixels  '          
TFORM9  = '1E      '          
TTYPE9  = 'angMajorAxis'       / Major axis position angle.
TUNIT9  = 'degrees '          
TFORM10 = '1E      '          
TTYPE10 = 'peak    '           / Peak of the gaussian fit.
TUNIT10 = 'DNs     '          
TFORM11 = '1E      '          
TTYPE11 = 'counts  '           / Sum of counts over sky.
TUNIT11 = 'DNs     '          
TFORM12 = '1J      '          
TTYPE12 = 'statusFit'          / 0=ok, else error.
[an error occurred while processing this directive]
END