On Sat, Mar 18, 2006 at 11:50:48 +0300,
Oleg Bartunov <oleg@sai.msu.su> wrote:
> I may be wrong but we in astronomy have several sky indexing schemes, which
> allows to effectively use classical btree index. See
> http://www.sai.msu.su/~megera/oddmuse/index.cgi/SkyPixelization
> for details. Sergei Koposov has developed Q3C contrib module for
> PostgreSQL 8.1+ and we use it with billiard size astronomical catalogs.
Note that Earth Distance can also be used for astronomy. If you use an
appropiate radius, distances will be in degrees.