Take the tour ×  I've been looking for a program to convert from
RA/dec into Alt/Az; having used a couple of online versions I
haven't seemed to find one yet that works reliably. I've tried
to do it myself and half the numbers end up spot on, but the
other half are way off. It's not something I can plug in
completely by hand, I need to convert about 300 images.  Is
there good code, a program, etc. that will honestly always give
back the right coordinates? Failing that, is it a common slip-up
messing up the values?  share|improve this question I should add
this would most helpfully be something that works in IDL/linux
or a ready-made spreadsheet –  Tan Apr 25 '12 at 21:33 add
comment  1 Answer  Did you convert RA to Hour Angle before
converting it to Azimuth?  HA = LST - RA (see here for a
description on how to do it)  If you need a program to do it,
then you should look up The IDL Astronomy User's Library
specifically the HADEC2ALTAZ (Convert Hour Angle and Declination
to Horizon (alt-az) coordinates) subrout