Thursday, September 29, 2016

Gaia star catalog for Celestia

The ESA's Gaia astrometric satellite has published its first Data Release, providing RA, Dec and parallax measurements for about 80% of the more than 2 million stars of the Hipparcos Tyco2 catalog. They provide RA and and Dec for another 2 billion or so stars, but they can't be used in Celestia without parallax measurements (distances). An updated DR2 is expected to be available in spring of 2018. For details, see http://sci.esa.int/gaia/

Although a 2 million star database is already available as an Addon for Celestia, most of its distances were derived using spectrographic and magnitude information and not a direct parallax measurement. As a result, they're relatively unreliable.

A revised version of Celestia's default stars.dat, containing about 110,000 stars, is available at https://www.classe.cornell.edu/~seb/celestia/files/gaia_stardb.zip  (about 2.75 MB, expands to  5.4 MB)

Revised versions of Pascal Hartmann's stars.dat containing 1 or 2 million stars are available at https://www.classe.cornell.edu/~seb/celestia/files/gaia_1_2m.zip  (about 51 MB, expands to about 59 MB)

Approximately 2/3 of the stars in each of those three stars.dat files have been updated with Gaia's distance measurements.

Interactive notebook: a WIP

I'm in the process of constructing an interactive notebook for use in Celestia, using Anim8or to design its components. It's interactive in the sense that the viewer can turn its pages, not that new entries can be written from within Celestia. Writing on a page has to be done "out of band" by painting the surface texture for each leaf of the notebook.

A sub-project was to create what looks like a taped-in photograph which will be used in several places. I have made it available on DeviantArt at http://celestiaguru.deviantart.com/art/Photo-03-taped-instant-photo-636917231