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### B.13.2 Examples

Here are some examples of `pixsample`:

    stilts pixsample in=szdata.fits pixdata=wmap_ilc_7yr_v4.fits
                     lat=GAL_LAT lon=GAL_LON pcmd='keepcols TEMPERATURE'
                     out=szdata_cmb.fits

  Samples from a HEALPix file containing WMAP data are added to an input file `szdata.fits`, giving an output file `szdata_cmb.fits` which is the same but with an additional column `TEMPERATURE`. The sampling is done using the default statistical mode `point`, which just takes a point sample at the input position. The HEALPix file must have its pixels ordered using galactic coordinates, since that is the coordinate system available from the input table.

  The pixdata file used here can be found (at time of writing) at https://lambda.gsfc.nasa.gov/data/map/dr4/dfp/ilc/wmap_ilc_7yr_v4.fits (24 Mbyte).

    stilts pixsample in=messier.xml pixdata=lambda_sfd_ebv.fits
                     stat=mean radius=5./60.
                     insys=icrs pixsys=galactic lon=RA2000 lat=DEC2000

  Samples data from a HEALPix table, averaging over a sampling radius of 5 arcmin. The coordinates in the input table are only available as ICRS (RA,Dec) coordinates, and the arrangement of the HEALPix pixels in the pixel data file uses galactic coordinates (you can only determine this by looking at the FITS headers or documentation of that file), so it is necessary to use the `insys` and `pixsys` parameters for conversion.

  The pixdata file used here can be found (at time of writing) at https://lambda.gsfc.nasa.gov/data/foregrounds/SFD/lambda_sfd_ebv.fits (25 Mbyte).

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Up: pixsample: Samples from a HEALPix pixel data file
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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk