[Kstars-devel] [soc] Bigger star catalogs

[Jason Harris]

Hello,

I have emailed USNO to see about getting a copy of the brightest 1%
(1e7 stars) and 10% (1e8 stars) of their USNO-B1 catalog.

While we wait for the reply, I went ahead and prepared the Tycho-2
catalog for our use.  It contains 2.45 million stars (compared to 1.0
million in our current Tycho-1 catalog).  Unfortunately, Tycho-2
doesn't include parallax values (so no distances), spectral types, HD
numbers or long names.  I therefore did a positional match to merge
these ancillary data from the Tycho-1 catalog, but we obviously only
have them for the 1 million stars in Tycho1.

The match used a maximum matching radius of 5 arcsec, with a caveat:
any match within 1 arcsec was accepted immediately, but if the best
match had an offset larger than 1 arcsec, then I further required that
the V mag values agree by < 0.2 mag.

I have attached tycho2_dr.png,  a histogram plot showing the
distribution of angular separation values for matched pairs.  The left
panel shows a linear y-axis, the right panel sows a logarithmic
y-axis.  As you can see, there's no discontinuity at r=1.0 arcsec, so
my double-radius strategy is probably ok.

The catalog is available here:
http://www.30doradus.org/kde/soc/tycho2_magsort.bz2  [38 MB]

The columns are:

HD   RA (Hours)   Dec (degrees)   pmRA (mas/yr)   pmDc (mas/yr)   Plx
(mas)   Vmag   B-V   binary?  variable?   SpType   gen-name :
long-name

regards,
Jason
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