Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

How does one draw a star chart like this?

I have:

  1. a star database with coordinates (right ascension - RA, declination - DEC),
  2. observer coordinates (latitude, longitude) and
  3. time of observation.

I need a formula which considers these parameters (mapping star coordinates to a 2D image). e.g.

starX = (90-abs(DEC)) * cos(RA)

starY = (90-abs(DEC)) * sin(RA)

share|improve this question

1 Answer 1

Try starting with this page from the US Naval Observatory. The formulas are pretty simple and give you azimuth and elevation. The star chart you linked is basically a polar plot then, with the azimuth being the angle of the plot and (90 - elevation) being the radius.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.