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How can I determine the parallactic angle of a target in pyEphem given a fixed object and an observer?

I am trying to use pyEphem to create an instrument simulator and I need to determine the rate at which the instrument rotator will be turning to de-rotate the field (this is an alt-az telescope), so really I'm trying to determine the rate of change of the parallactic angle.

thanks, Josh

Josh
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  • It does not look like any of the quantities provided by PyEphem, glancing over the Quick Reference, are directly related or proportional to the parallactic angle; please feel welcome to go over to PyEphem on GitHub, and create an issue asking whether this could be a future feature of the library. I suspect that it will require copying a formula from spherical trigonomy. https://github.com/brandon-rhodes/pyephem/issues?state=closed – Brandon Rhodes Aug 14 '13 at 10:50
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    One other thought: if you are ambitious and want to try avoiding the “off-topic” accusation that has been made against your question, then you might try adding a code sample where you create an astronomical body using PyEphem, create an observer, ask the body where it is when viewed from that observer, and then state what the resulting parallactic angle *should* be for that precise circumstance, if only you had some way to compute it. Otherwise, it looks like, there is fear the question is too open-ended. Good luck, and I hope you succeed—it's a good question! – Brandon Rhodes Aug 14 '13 at 19:13

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