I'm no math whiz, and I don't even fully understand the trigonometric formulas, however all care was taken to ensure that the porting of the functions to PHP and associated code is good enough to generate object precision to within 1 degree.
All deep sky objects utilise the Saguaro Astonomy Club's database version 8. I haven't modified their data in any way, merely downloaded the freely available CSV and inserted it into a SQL database. I don't know them, I'm not affiliated with them in any way; when I was searching for a star database they happened to be the first easy to use db that I could find ;)
All constellations are generally positioned at right ascension and declination values as close to the 'middle' of the constellation as I can figure, usually rounded to the nearest whole hour and degree.
The azimuthal directions (eg 'south') used to help the viewer get a feel for where to look are based on true north (not magnetic variation).
Images representing the moon's luminosity have been grabbed from the IceInSpace site. (And indeed, much credit goes to the community there for the ongoing inspiration to create this little project of mine.)