Corrected Frame

File Format: FITS image

Name: fpC-rrrrrr-bc-ffff.fit, where rrrrrr is the imaging run number, b is the filter used (u, g, r, i, or z), c is the column location in the Imaging Array of the CCD which acquired the data (1-6), and ffff is the field number within the run.

Produced by: frames

Used by:

Size: 5,581.44 Kb per file. 5 files per field. Total of 27,907.2 Mb for a single frames pipeline run with 1000 fields.

Archived? Yes. Tracked file.

Description

DR1 fpC frames (photo v5_3)

The corrected frame, having been bias subtracted, flat-fielded, and purged of bright stars. A fit to the sky is not subtracted, but stored in the header keyword SKY - this is a change between the EDR data and the DR1 data.

An offset of SOFTBIAS is added to each pixel to avoid negative pixel values. Thus, in the image the "sky" will everywhere equal approximately SOFTBIAS + SKY.

There is one more new keyword in DR1 data which helps with quick photometric calibration: FLUX20, the flux for a 20th magnitude object. (A FLUX0 field is also written but not calculated.)

Note that FLUX20 is calculated from a preliminary photometric calibration. The full photometric calibration is calculated only after fpC frames have been written. To use the full calibration, you will need the zeropoint aa and extinction coefficient kk from the tsField file.

EDR fpC frames (photo v5_2)

The corrected frame, having been bias subtracted, flat-fielded, purged of bright stars, and sky subtracted. After subtracting a fit to the sky, an offset of SOFTBIAS is added to each pixel to avoid negative pixel values. Thus, in the image the "sky" will everywhere equal approximately SOFTBIAS.

Primary Header

All of the header parameters from the raw image are inherited as well.

DR1 versions of fpC (photo v5_3)

The following is just the copy of an fpC fits file header as produced by the current version of the frames pipeline (v5_3_53 or so). See below for an old version (probably not even adequate for EDR).
SIMPLE  =                    T
BITPIX  =                   16
NAXIS   =                    2
NAXIS1  =                 2048
NAXIS2  =                 1489
BZERO   = 3.27680000000000E+04
BSCALE  = 1.00000000000000E+00
TAI     =        4461556376.78 / 1st row - Number of seconds since Nov 17 1858
RA      =            252.64468 / 1st row - Right ascension of telescope boresigh
DEC     =            65.127927 / 1st row - Declination of telescope boresight (d
SPA     =             155.615  / 1st row - Camera col position angle wrt north (
IPA     =             294.868  / 1st row - Instrument rotator position angle (de
IPARATE =              0.0004  / 1st row - Instrument rotator angular velocity (
AZ      =            160.80974 / 1st row - Azimuth  (encoder) of tele (0=N?) (de
ALT     =            53.523581 / 1st row - Altitude (encoder) of tele        (de
FOCUS   = -999999999999.999999 / 1st row - Focus piston (microns?)
DATE-OBS= '2000-04-04'         / 1st row - TAI date
TAIHMS  = '09:12:56.77'        / 1st row - TAI time (HH:MM:SS.SS) (TAI-UT = appr
COMMENT  TAI,RA,DEC,SPA,IPA,IPARATE,AZ,ALT,FOCUS at reading of col 0, row 0
BUNITS  = 'ADUs    '
ORIGIN  = 'SDSS    '
TELESCOP= '2.5m    '
TIMESYS = 'TAI     '
RUN     =                 1336 / Run number
FRAME   =                   11 / Frame sequence number within the run
CCDLOC  =                   11 / Survey location of CCD (e.g., rowCol)
STRIPE  =                   42 / Stripe index number (23 <--> eta=0)
STRIP   = 'N       '           / Strip in the stripe being tracked.
FLAVOR  = 'science '           / Flavor of this run
SYS_SCN = 'mean    '           / System of the scan great circle (e.g., mean)
EQNX_SCN=           2000.00    / Equinox of the scan great circle. (years)
NODE    =           95.00000   / RA of the great circle's ascending node (deg)
INCL    =           80.00000   / Great circle's inclination wrt cel. eq. (deg)
XBORE   =           -22.74     / Boresight x offset from the array center (mm)
YBORE   =           0.00       / Boresight x offset from the array center (mm)
OBJECT  = '42 N    '           / e.g., 'stripe 50.6 degrees, north strip'
EXPTIME = '53.907456'          / Exposure time (seconds)
EQUINOX = '2000.0  '           / Equinox of the TCC coordinates (years)
SYSTEM  = 'FK5     '           / System of the TCC coordinates (e.g., mean)
CCDMODE = 'DRIFT   '           / 'STARING' or 'DRIFT'
C_OBS   =                26322 / CCD row clock rate (usec/row)
COLBIN  =                    1 / Binning factor perpendicular to the columns
ROWBIN  =                    1 / Binning factor perpendicular to the rows
DAVERS  = 'v14_20  '           / Version of DA software
COMMENT  CCD-specific parameters
CAMROW  =                    1 / Row in the imaging camera
BADLINES=                    0 / Number of bad lines in frame
SOFTBIAS=                 1000 / software "bias" added to all DN
FLUX20  = 2.05987000000000E+03 / Number of DN in 20th mag object
FLUX0   = -9.9990000000000E+03 / Number of DN in 0th mag object
FCALI_ID= 'None    '
SKY     = 1.30960000000000E+02 / Approx. sky level (DN)
BUNIT   = 'DNs     '
FILTER  = 'r       '           / filter used
CAMCOL  =                    1 / column in the imaging camera
VERSION = 'XXX     '           / Version of photo used.
DERV_VER= 'v8_15   '           / Version of dervish used
ASTR_VER= 'v5_13   '           / Version of astrotools used
ASTRO_ID= 'XXX     '           / Astrometric pipeline run identifier.
BIAS_ID = 'XXX     '           / Bias pipeline run identifier.
FRAME_ID= 'XXX     '           / Frames pipeline run identifier.
KO_VER  = 'XXX     '           / Version of known object catalog used.
PS_ID   = '2002-09-04T17:49:34 19844 camCol 1'
ATVSN   = 'v5_13   '           / ASTROTOOLS version tag
RADECSYS= 'ICRS    '           / International Celestial Reference Sys
CTYPE1  = 'DEC--TAN'           / X (Column) Axis Projection
CTYPE2  = 'RA---TAN'           / Y (Row) Axis Projection
CUNIT1  = 'deg     '           / Column Axis Units
CUNIT2  = 'deg     '           / Row Axis Units
CRPIX1  = 1.02450000000000E+03 / Column Pixel Coordinate of Reference
CRPIX2  = 7.44500000000000E+02 / Row Pixel Coordinate of Reference Pix
CRVAL1  = 6.42142612400000E+01 / DEC at Reference Pixel
CRVAL2  = 2.51207342810000E+02 / RA at Reference Pixel
CD1_1   = 4.75626416015645E-05 / DEC degrees per column pixel
CD1_2   = -9.9116868279565E-05 / DEC degrees per row pixel
CD2_1   = 9.91802898939385E-05 / RA  degrees per column pixel
CD2_2   = 4.76632658513898E-05 / RA  degrees per row pixel
END

The following is probably completely out of date

The following is out of date at least for DR1. I am leaving it in in case it applies to EDR data, but looking at an EDR fpc file, I doubt even that. See above for a DR1 version copied from a DR1 fpC file.

SIMPLE  =                    T
BITPIX  =                   16
NAXIS   =                    2
NAXIS1  =                 2048
NAXIS2  =                 1489
BSCALE  =                    1
BZERO   =                32768
VERSION = 'XXX     '           / Version of software used.
PS_ID   = 'XXX     '           / Postage stamp pipeline run identifier.
BIAS_ID = 'XXX     '           / Bias pipeline run identifier.
ASTRO_ID= 'XXX     '           / Astrometric pipeline run identifier.
FRAME_ID= 'XXX     '           / Frames pipeline run identifier.
KO_VER  = 'XXX     '           / Version of known object catalog used.
RUN     =                  XXX / Imaging run number.
CAMCOL  =                  XXX / Column in the imaging camera.
FIELD   =                  XXX / Field sequence number within the run.
FILTER  = 'XXX     '           / Filter (u, g, r, i, or z).
TAI     =        XXXXXXXXXX.XX / Number of seconds since Nov 17 1858 0 TAI
RA      =           XXX.XXXXXX / Right ascension of telescope boresight (deg)
DEC     =           XXX.XXXXXX / Declination of telescope boresight (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 tele (0=N?) (degrees)
ALT     =           XXX.XXXXXX / Altitude(encoder) of tele        (degrees)
FOCUS   =           XXXXX.X    / Focus piston (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)
CCDLOC  =                  XXX / Survey location of CCD (e.g., rowCol)
FRAME   =                  XXX / Frame sequence number within the run
DAVERS  = 'XXX     '           / Version of DA software
RADECSYS= 'ICRS    '           / International Celestial Reference Sys
CTYPE1  = 'DEC--TAN'           / X (Column) Axis Projection
CTYPE2  = 'RA---TAN'           / Y (Row) Axis Projection
CUNIT1  = 'deg     '           / Column Axis Units
CUNIT2  = 'deg     '           / Row Axis Units
CRPIX1  = 1.02400000000000E+03 / Column Pixel Coordinate of Reference
CRPIX2  = 6.80000000000000E+02 / Row Pixel Coordinate of Reference Pix
CRVAL1  = -3.1788873000000E-01 / DEC at Reference Pixel
CRVAL2  = 1.88473355950000E+02 / RA at Reference Pixel
CD1_1   = 1.10005818270640E-04 / DEC degrees per column pixel
CD1_2   = 1.31691176470661E-08 / DEC degrees per row pixel
CD2_1   = -4.1308597225549E-08 / RA  degrees per column pixel
CD2_2   = 1.09963954550070E-04 / RA  degrees per row pixel
END