I've often come across sun path charts like this (Wikimedia Commons) that show the position of the sun at any point of the year, at any time of day, for a specific location (or a set of locations), on an azimuth-elevation polar plot:

enter image description here

I'd like to get the exact same chart (or data, to create my own chart) for any given star, such as Aldebaran or Sirius, for a given point on Earth.

I'm looking into Stellarium scripting, as well as the HYG stellar database (I am not familiar with the mathematics of right ascension and declination, or how to convert this to azimuth-elevation like in the example). Is this a very unusual data product to ask for?

  • $\begingroup$ It's actually must simpler for a single star, since the right ascension and declination are constant. $\endgroup$ – user21 Oct 22 '15 at 11:19
  • $\begingroup$ Right, last night I got the code working to convert {RA, dec, lat, lon, time} to {az, el} and got started on the code to plot it in a web browser. I see that the Sun has a right ascension and declination too—can't I use that with my converter code to generate a solar path plot like the example given? $\endgroup$ – Ahmed Fasih Oct 22 '15 at 11:26
  • $\begingroup$ Correct. Your path will look like one of the blue lines in the sun diagram, since the sun's declination on a given day is fairly constant. $\endgroup$ – user21 Oct 22 '15 at 11:27

I wrote some JavaScript to help answer my question. It's in terrible shape right now, but it plots the hourly position of Aldebaran in azimuth & elevation when viewed from Dayton, Ohio, USA, every fortnight for a year:


The source code is at https://github.com/fasiha/starpath but everything in it is hardcoded. However, when I have a bit of time, I can make it into a nice little webapp where you can input your position and select a celestial object (or inputs its RA/dec) and see the same plot—possibly along with information about when the sun obscures it.


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