Celestia Forums

On investigation into the format of stars.dat, I find that in the extended database there are stars with Hipparcos fields which are outside the range of star catalog numbers in the Hipparcos catalog.

I presume these are Tycho stars, because the starnames.dat does not contain Tycho catalog numbers as mapping from nonexistant Hipparcos numbers, yet the program identifies these.

However I identified a star in the Tycho catalog which was a duplicate, however that star does not appear to exist with even one copy, presuming that the number ABCDEFGH stored in the Hipparcos catalog field (where A-H represent single decimal digits) represents a Tycho star with catalog number ABCD-EFG-H.

So how does Celestia identify which Hipparcos numbers are Tycho stars, and how does it get the Tycho catalog number?

chaos,

You need to read Pascal's Web page describing how the extended database was created. See the last few paragraphs on http://perso.wanadoo.fr/celestia.stars/newcat.html

I hope this helps.

Thanks, I've now identified the duplicate as TYC 2726-3367-0