Comment 4 for bug 1690615

Alexander, the fast algorithm used to identify position to constellations is correct as described in the paper. Indeed, in 1926 (or 1931? cannot remember, not so important here) IAU defined constellation boundaries in J1875 (or maybe even B1875?) equinox. Any difference B1875/J1875 should be negligible in this context, though.

What needs to be done for stars is transformation of positions for equinox&epoch Jnow->equinox 1875 (or epoch Jnow in J2000 frame and J2000->J1875, in any case only precession! Proper motion for Jnow, not 1875!!) and check positions. Maybe currently we just check epoch J2000 positions (for efficiency). I had assigned this low-priority issue to myself and intended to look into the code a bit later.