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### B.39.2 Examples

Here are some examples of using `tskymatch2`:

    stilts tskymatch2 in1=obs_v.xml in2=obs_i.xml out=obs_iv.xml \
                      ra1=OBS_RA dec1=OBS_DEC ra2=OBS_RA dec2=OBS_DEC error=2

  Takes two input catalogues (VOTables), one with observations in the V band and the other in the I band, and performs a match to find objects within 2 arcseconds of each other. The result is a new VOTable containing only rows where a match was found.

    stilts tskymatch2 in1=obs_v.xml in2=obs_i.xml out=obs_iv.xml \
                      error=2

  This is the same as the previous example but without explicit specification of the sky position columns in either table. It will work only if those columns are identified with appropriate UCDs, for instance `pos.eq.ra;meta.main` and `pos.eq.dec:meta.main`. If no suitable UCDs are in place this invocation will fail with an error.

    stilts tskymatch2 in1=virgo1.txt ifmt1=ascii in2=mgc.fits \
                      ra1='radiansToDegrees(raRad)' dec1='radiansToDegrees(deRad)' \
                      ra2=MGC_ALPHA_J2000 dec2=MGC_DELTA_J2000 \
                      error=10 join=2not1 omode=count

  Object positions in the text file virgo1.txt are compared to those in the FITS file mgc.fits. The angles have been recorded in the text file in radians, so they are converted to degrees here before use. Use of the `join=2not1` parameter causes the command to identify all the objects in the first list which do not have counterparts within 10 arcsec in the second list. The number of such objects found is simply output to the terminal.

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Next: votcopy: Transforms between VOTable encodings
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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