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Re: Star-to-Star Distances and Stellarium
From: Peter Monta
Date: 2014 Aug 23, 20:00 -0700

Hi Sean,

... I decided to use Stellarium to check my results as I went, even though I wasn't sure whether or not Stellarium displays the effects of refraction.

I believe it does account for refraction---if you have "show atmosphere" enabled under "sky and viewing options", a selected object will show both geometric and apparent altitudes in the list on the upper left of the screen, the difference being the refraction. The configuration window also allows you to set the barometric pressure and temperature for the model.

But I had enough confidence in my own ability to figure it out. Once I started, I found all three measurements to be within 1.0' of what Stellarium displayed after I corrected for the +1.0' I.E. The Polaris-Schedar measurement was only 0.1' off. I used the "angle measuring" plug-in and froze the simulation at the time of each observation. I'd be interested to hear if anyone else could get the same results.

I do have one beef with the angle-measurement tool, though---it doesn't snap to objects! You have to get it as close as you can manually. I should send them a feature request.

I've found the angle-measuring tool useful for interactively exploring good geometries on any given night for "rusty sextant" experiments in which one sets the sextant to a certain angle, then waits for both a star-star and a star-moon distance to coincide with it. Can quickly find sets of bright stars with nearly the right distances.

Cheers,
Peter

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