1

Recently, I started processing tle data using pyorbital python library. I would like to get the solar zenith angle using this function:

astronomy.sun_zenith_angle(utc_time, lon, lat)

In degrees, I get a number between 0° and 180°. I don't really understand this range, because if I understand well, the solar zenith angle is between -180° and 180°. I hope, you can help me!

Gábor Kreinicker
  • 11
  • 2
  • For that you should probably ask the authors directly, for example here https://github.com/pytroll/pyorbital/issues . Or you could have a look at the code here https://github.com/pytroll/pyorbital/blob/1bf73c834befb6d7f060c636dae85bb91230a556/pyorbital/astronomy.py#L147 and see if the implementation makes sense. – Nikolay Hüttenberend Mar 11 '22 at 10:37
  • The documentation contains this: *"Sun-zenith angle for lon, lat at utc_time. lon,lat in degrees. The angle returned is given in degrees"* here is the link: https://readthedocs.org/projects/pyorbital/downloads/pdf/latest/ From this doc you can find the reference angles discussed here: http://www.geoastro.de/elevaz/basics/index.htm – D.L Mar 12 '22 at 08:21
  • Thank you all! I watched these pages and I think I understood everything about it, thanks again! In the meantime, it turned out that these aren't what I needed. Then I found the "eci_sun" coordinates, which I needed and what I didn't get straight from this library. I finally got these through "predict.c": https://github.com/nsat/pypredict/blob/master/predict.c Thank you for your help! – Gábor Kreinicker Apr 23 '22 at 19:12

0 Answers0