Field Fang File

File Format: FITS binary table

Name: scFang-rrrrrr-c-ffff.fit for those produced by SSC, psFang-rrrrrr-c-ffff.fit for those produced by PSP, where rrrrrr is the imaging run number, c is the column location in the Imaging Array of the CCD which acquired the data (1-11), and ffff is the field number within the run.

Produced by: ssc, ps

Used by: astrom, ps

Size: 2880 * 37 + 5 * (8454 * Nstars {rounded up to multiple of 2880}) + 7 * (50 * Nstars {rounded up to multiple of 2880}) bytes per file for columns 1-6. 2880 * 7 + 2 * (50 * Nstars {rounded to multiple of 2880}) bytes per file for columns 7-11. Columns 7-11 may not be present. For a field with 100 stars, this gives 4,380.48 Kb per file for a photometric column, and 31.68 Kb per file for an overlap column. Total of 26,441.28 Mb for all 11 columns of a run with 1000 fields.

Archived? Yes, but only the measured stellar parameters.

Description

The primary function of the Serial Stamp Collection Pipeline is, for each field, to: form a subset of the stars detected by the DA Online Bright Star Finder on both the leading and trailing astrometric chips; cut out associated postage stamps matching that subset in the photometric frames; measure the same set of stellar parameters as are measured in the DA system for the stars in the new postage stamps. This file saves those results. The stellar parameters for all frames in each field (including those measured by the DA system on the astrometric chips) are saved in this file, as well as the postage stamps for the photometric frames. Additionally, the frame-specific TCC-supplied header information (e.g., telescope boresight pointing, TAI, instrument rotation angle, etc) and quartiles are copied from the DA gang files, thus grouping this information by field such that the postage stamp pipeline need not read the DA gang files.

For overlap columns (columns 7-11), only the measured stellar parameter HDUs are written.

PSP reads the FANG files produced by SSC, corrects the centroids based on the measured PSFs, and writes out new FANG files containing the measured star parameters only.

The order of stamps and stars within each HDU is important. Each stamp/star matches up with the other stamps/stars occupying the same position in the other HDUs.

The order of HDUs is given by the [SPQ]FILTERS and HDUSETS keywords in the PDU. For example, for SSC FANG files for photometric columns:

HDUSETS = 'stamps params quarts' / order of HDU sets in the file
SFILTERS= 'r i u z g'	       / Filters processed for postage stamps.
PFILTERS= 'l r i u z g t'      / Filters processed for bright star params.
QFILTERS= 'r i u z g'	       / Filters processed for quartile/flats.
while for overlap columns:
HDUSETS = 'params'	       / order of HDU sets in the file
PFILTERS= 'o s'                / Filters (rows in the imaging camera) processed.
Thus, the order of HDUs is:

HDUs (cols 1-6):

1-5:postage stamps for riuzg cutouts

6-12: bright star params for lriuzgt

13-17: flats/quart for riuzg

HDUs (cols 7-11):

1-2: bright star params for o,s (overlap rows)

For FANGs produced by PSP:

HDUSETS = 'params'	       / order of HDU sets in the file
PFILTERS= 'l r i u z g t'      / Filters (rows in the imaging camera) processed.
NOTE: This is an illegal fits file, as it uses unsigned shorts. Even more illegal, it says "SIMPLE = T". Buyer beware!

Primary Header

For SSC FANG files, VERSION is the SSC pipeline version. For PS FANG files, VERSION is the PS pipeline version. The keyword PS_ID is present for PS FANG files only.

SIMPLE  =                    T
BITPIX  =                    8
NAXIS   =                    0
EXTEND  =                    T
VERSION = 'XXX     '           / Version of software used.
RUN     =                  XXX / Imaging run number.
CAMCOL  =                  XXX / Column in imaging camera.
SSC_ID  = 'XXX     '           / SSC pipeline run identifier.
PS_ID   = 'XXX     '           / PSP pipeline run identifier (PSP FANGS only)
KO_VER  = 'XXX     '           / Version of known object catalog used.
FIELD   =                  XXX / Field sequence number within the run.  
HDUSETS = 'stamps params quarts' / Order of HDU sets in the file.
SFILTERS= 'r i u z g'          / Filters processed for postage stamps.
PFILTERS= 'l r i u z g t'      / Filters processed for bright star params.
QFILTERS= 'r i u z g'          / Filters processed for quartile/flats.
END

Postage Stamps Header

One HDU of this format is created for each photometric CCD in the column (usually 5 for columns 1-6, always 0 for columns 7-11).

XTENSION= 'BINTABLE'
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                 8454
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                    3
EXTNAME = 'STAMP LOC'
CAMROW  =                  XXX / Row in imaging camera
FILTER  = 'XXX     '           / Filter for Row in imaging camera
PSSIZE  =                   65 / Postage Stamp Size
TSHIFT  =                  XXX / Bias scaling factor
FRBIASL =                  XXX / Left  Frame bias x TSHIFT
FRBIASR =                  XXX / Right Frame bias x TSHIFT
FROSCNL =                  XXX / Left Mean Oscn Value x TSHIFT
FROSCNR =                  XXX / Right Mean Oscn Value x TSHIFT
TFORM1  = '4225U   '           / PostStamp shorts
TTYPE1  = 'pixelMap'           / Postage Stamp subimage
TZERO1  =                32768
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

One HDU of this type is created for each CCD in the column (usually 7 for columns 1-6, 2 for columns 7-11). The instrumental colors are set to:
     -2.5 * log(counts1/counts2)
A bad color is flagged with the value -99.

[an error occurred while processing this directive]

XTENSION= 'BINTABLE'          
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                   58
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                   15
[an error occurred while processing this directive]
EXTNAME = 'STAR LOC'
RUN     =                  XXX / Imaging run number.
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)
BIAS    =                  XXX / Number of columns of bias per amplifier.
OVERSCAN=                  XXX / Number of columns of overscan per amplifier.
FRAME   =                  XXX / Frame number.
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)
CAMCOL  =                  XXX / Column in the imaging camera. (astro chips only)
CAMROW  =                  XXX / Row in imaging camera
FILTER  = 'XXX     '           / Filter for Row in imaging 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 = '1E      '          
TTYPE12 = 'color   '           / Instrumental color.
TFORM13 = '1E      '          
TTYPE13 = 'colorErr'           / Instrumental color. (error)
TFORM14 = '1J      '          
TTYPE14 = 'statusFit'          / 0=ok, else error.
TFORM15 = '1I      '          
TTYPE15 = 'sscStatus'          / 0=ok,1=bad radius,2=bad peak,4=photo only
COMMENT                        / -9=dummy entry (not found on this chip)
[an error occurred while processing this directive]
END

Quartiles and Flats Header

One HDU of this type is created for each photometric chip (usually 5). This is a straight copy of the quartile HDU from the DA Gang file, with an added field for a flatfield calculation. Below, NAXIS2 will be equal to 2128.

[an error occurred while processing this directive]

XTENSION= 'BINTABLE'          
BITPIX  =                    8
NAXIS   =                    2
NAXIS1  =                   16
NAXIS2  =                  XXX
PCOUNT  =                    0
GCOUNT  =                    1
TFIELDS =                    4
[an error occurred while processing this directive]
EXTNAME = 'QFLAT LOC'
CAMROW  =                    1 / Row in imaging camera
FILTER  = 'XXX     '           / Filter for 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
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'     
TFORM4  = '1J      '          
TTYPE4  = 'flatVal '           / Flat field value (similar to q2).
TUNIT4  = 'ADUs x TSHIFT'     
[an error occurred while processing this directive]
END