SRoll multibolometer polarized maps FITS files are formatted in the same way as in the Planck Legacy Archive (PLA) HFI2018 release:
http://pla.esac.esa.int/pla/#maps
as documented in the PLA explanatory supplement:
https://wiki.cosmos.esa.int/planck-legacy-archive/index.php/Frequency_maps
More explicitly, each FITS file contains a first (primary) header without data, and an extension with a header and a 10 column table. Each column is a HEALPix map at Nside=2048, in GALACTIC coordinates and NESTED ordering. The first three columns are the I_STOKES, Q_STOKES and U_STOKES components in single precision floating point, the fourth column is the HIT count map in 32bit integer, and the last six columns are the upper triangular part of the 3x3 symmetric covariance matrix, II, IQ, IU, QQ, QU and UU respectively, in single precision floating point data type.
The output of the fitsheader command (http://docs.astropy.org/en/stable/io/fits/usage/scripts.html) on one of these files is given here for further documentation:
$ fitsheader SRoll20_SkyMap_100psb_full.fits # HDU 0 in SRoll20_SkyMap_100psb_full.fits: SIMPLE = T / conforms to FITS standard BITPIX = 8 / array data type NAXIS = 0 / number of array dimensions EXTEND = T # HDU 1 in SRoll20_SkyMap_100psb_full.fits: XTENSION= 'BINTABLE' / binary table extension BITPIX = 8 / array data type NAXIS = 2 / number of array dimensions NAXIS1 = 40 / length of dimension 1 NAXIS2 = 50331648 / length of dimension 2 PCOUNT = 0 / number of group parameters GCOUNT = 1 / number of groups TFIELDS = 10 / number of table fields TTYPE1 = 'I_STOKES' TFORM1 = 'E ' TUNIT1 = 'Kcmb ' TTYPE2 = 'Q_STOKES' TFORM2 = 'E ' TUNIT2 = 'Kcmb ' TTYPE3 = 'U_STOKES' TFORM3 = 'E ' TUNIT3 = 'Kcmb ' TTYPE4 = 'HITS ' TFORM4 = 'J ' TUNIT4 = '' TTYPE5 = 'II_COV ' TFORM5 = 'E ' TUNIT5 = 'Kcmb^2 ' TTYPE6 = 'IQ_COV ' TFORM6 = 'E ' TUNIT6 = 'Kcmb^2 ' TTYPE7 = 'IU_COV ' TFORM7 = 'E ' TUNIT7 = 'Kcmb^2 ' TTYPE8 = 'QQ_COV ' TFORM8 = 'E ' TUNIT8 = 'Kcmb^2 ' TTYPE9 = 'QU_COV ' TFORM9 = 'E ' TUNIT9 = 'Kcmb^2 ' TTYPE10 = 'UU_COV ' TFORM10 = 'E ' TUNIT10 = 'Kcmb^2 ' PIXTYPE = 'HEALPIX ' / HEALPIX pixelisation ORDERING= 'NESTED ' / Pixel ordering scheme, either RING or NESTED COORDSYS= 'GALACTIC' / Ecliptic, Galactic or Celestial (equatorial) EXTNAME = 'FREQ-MAP' / Extension name NSIDE = 2048 / Resolution parameter of HEALPIX FIRSTPIX= 0 / First pixel # (0 based) LASTPIX = 50331647 / Last pixel # (0 based) INDXSCHM= 'IMPLICIT' / Indexing: IMPLICIT or EXPLICIT OBJECT = 'FULLSKY ' / Sky coverage, either FULLSKY or PARTIAL BAD_DATA= -1.6375E+30 / HEALPIX bad pixel value DATE = '2018-12-27' / Creation date (YYYY-MM-DD) POLCCONV= 'COSMO ' / Polarization convention FILENAME= 'SRoll20_SkyMap_100psb_full.fits' / FITS filename FREQ = '100 ' / reference frequency PROCVER = 'SRoll20 ' / Product version UNITFREQ= 'GHz ' / frequency units BNDCTR = '100 ' / band center, same as FREQ RESTFRQ = 100.89 / effective frequency BNDWID = '33 ' / effective bandwidth (approximate) PROCDSET= '100psb ' / processed detector set PROCRSET= 'full ' / processed ring set PLOTDSET= '100psb ' / plotted detector set PLOTRSET= 'full ' / plotted ring set
545 GHz and 857 GHz HFI channels don't contain polarization sensitive bolometers and their frequency maps are therfore intensity only. They nevertheless follow the same formatting as the Planck 2018 FITS files, the only difference being the content of the columns in the FITS file extension.
The multibolometer unpolarized maps FITS file extension columns are:
They also use the same formatting as the Planck 2018 FITS files, with the following columns:
They still use the same formatting as the Planck 2018 FITS files, with the following columns: