Here are some examples of using tskymap
:
stilts tskymap in=iras_psc.fits lon=RA lat=DEC out=iras_map.csv
stilts tskymap in=iras_psc.fits lon=RA lat=DEC tiling=hpx6 ocmd='healpixmeta -csys C' ofmt=fits-healpix out=iras_map.fits
ofmt=fits-healpix
,
which writes a FITS file following the
HEALPix-FITS convention.
An additional filter
"healpixmeta -csys C
"
is also supplied here: this indicates that the HEALPix pixels in
the output file are to be considered in the Celestial
(=equatorial) sky system. If this is not done, Aladin assumes the
coordinate system to be Galactic and will align the results incorrectly
on the sky.
stilts tskymap in=2mpz.fits icmd='addskycoords fk5 galactic ra dec glon glat' lon=glon lat=glat tiling=hpx6 cols='jCorr-hCorr hCorr-kCorr jCorr-kCorr' combine=median count=false complete=true out=2mpzColors.fits
addskycoords
filter has been used so that the grid
is laid on the sky with galactic coordinates.
Setting complete=true
guarantees that a row is written
to the output file for every sky pixel, including empty ones.
Note in this case that the output format is not specified explicitly,
so it will be inferred from the filename, to be "normal" FITS,
rather than healpix-fits
. The output data will still be
present, but external applications may not automatically
identify the pixel column.
stilts tskymap in=tgas_source.fits tiling=hpx7 lon=l lat=b count=false cols=phot_g_n_obs combine=sum-per-unit perunit=arcmin2 ofmt=fits-healpix ocmd='healpixmeta -csys G' out=obs-density.fits
phot_g_n_obs
values from the
input table that fall into each tile and applying a suitable
scaling factor. The grid coordinate system is explicitly labelled
as Galactic.
stilts tskymap in=gaia_source.colfits tiling=hpx8 lon=l lat=b count=true cols='bp_rp;mean phot_bp_mean_flux;sum phot_rp_mean_flux;sum' out=gaia-stats.fits
bp_rp
column and the summed values of the phot_bp_mean_flux
and
phot_rp_mean_flux
columns for each HEALPix level 8 tile,
as well as the source density.
stilts tskymap in=gums_lmc.fits lon=alpha lat=delta tiling=hpx14 complete=false omode=count
complete=false
, only rows for non-empty pixels
are included in the output table. Then, since the output mode is
count
, these rows are just counted, discarding the
pixels themselves, giving the number of level-14 healpix pixels
touched by the sources in this input file.
Note this is not necessarily the most efficient way to calculate
coverage information.