IRAS Sky Survey Atlas
FITS Header Information

Primary Header

SIMPLE  =                    T / file does conform to FITS standard
BITPIX  =                    8 / number of bits per data pixel
NAXIS   =                    0 / number of data axes
EXTEND  =                    T / FITS dataset may contain extensions
COMMENT   FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT   and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
DATE    = '2005-02-03'         / file creation date (YYYY-MM-DD)
TELESCOP= 'IRAS    '           / Infrared Astronomical Satellite
OBJECT  = 'ALL-SKY '           / Portion of sky given
COMMENT   This file contains a HEALPix map of  25 micron intensity formed from
COMMENT   IRAS Sky Survey Atlas (ISSA) data.  It was made by averaging the
COMMENT   coadded (HCON 0) ISSA data over HEALPix pixels.  Overlapping data
COMMENT   between neighboring ISSA fields were excluded.  All of the ISSA fields
COMMENT   were used, including the Reject fields at low ecliptic latitudes where
COMMENT   residuals after subtraction of the zodiacal emission model are
COMMENT   significant.  Minor discontinuities are present at field boundaries
COMMENT   at some locations in the map, due to intensity differences between
COMMENT   neighboring fields at low ecliptic or Galactic latitude.  Sky coverage
COMMENT   is about 98%, and intensity values are set to -32768 for HEALPix
COMMENT   pixels that contain no ISSA data.
REFERENC= 'Legacy Archive for Microwave Background Data Analysis (LAMBDA)      '
REFERENC= '                http://lambda.gsfc.nasa.gov/                        '
REFERENC= 'IRAS Sky Survey Atlas Explanatory Supplement,                       '
REFERENC= ' Wheelock, S.L., et al., 1994, JPL Publication 94-11 (Pasadena: JPL)'
REFERENC= ' http://lambda/product/iras/docs/issa.exp.sup/                      '
REFERENC= 'HEALPix Home Page: http://www.eso.org/science/healpix/              '
FREQ    = ' 25 micron band'    / Wavelength band
RESOLUTN=                   10 / Resolution index
SKYCOORD= 'Galactic'           / Coordinate system
PIXTYPE = 'HEALPIX '           / Pixel algorithm
ORDERING= 'NESTED  '           / Ordering scheme
NSIDE   =                 1024 / Resolution parameter
NPIX    =             12582912 / # of pixels
FIRSTPIX=                    0 / First pixel (0 based)
LASTPIX =             12582911 / Last pixel (0 based)
END

Extension Header #1

XTENSION= 'BINTABLE'           /binary table extension
BITPIX  =                    8 /8-bit bytes
NAXIS   =                    2 /2-dimensional binary table
NAXIS1  =                    8 /width of table in bytes
NAXIS2  =             12582912 /number of rows in table
PCOUNT  =                    0 /size of special data area
GCOUNT  =                    1 /one data group (required keyword)
TFIELDS =                    2 /number of fields in each row
TTYPE1  = 'Intensity'          /label for field   1
TFORM1  = '1E      '           /data format of field: 4-byte REAL
TUNIT1  = 'MJy/sr  '           /physical unit of field
COMMENT   Average of IRAS Sky Survey Atlas  25 micron data over HEALPix pixels
TTYPE2  = 'N_PIXELS'           /label for field   2
TFORM2  = '1E      '           /data format of field: 4-byte REAL
TUNIT2  = 'ISSA pixel count'   /physical unit of field
COMMENT   Number of ISSA pixels contributing to each HEALPix pixel
EXTNAME = 'Archive Map Table'  /name of this binary table extension
DATE    = '2005-02-03'         /Table/MAP creation date (YYYY-MM-DD)
PIXTYPE = 'HEALPIX '           /Pixel algorithm
ORDERING= 'NESTED  '           /Ordering scheme
NSIDE   =                 1024 /Resolution parameter
FIRSTPIX=                    0 /First pixel (0 based)
LASTPIX =             12582911 /Last pixel (0 based)
END

More information concerning the format of this file is available.