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Re: Astro-Photos class
From: Peter Monta
Date: 2015 May 11, 20:56 -0700

Hi Frank,

I'm teaching an "Easy Astro Photos" class this coming weekend (May 16-17, 2015) at Mystic Seaport.

Sounds great---I hope you and your students enjoy the class.

Here's a photo I took back in early March (I debated whether to post it to NavList at the time). It's a wide-field shot of a satellite trail; I have several of these from the same evening with pretty good coverage in ground-track azimuth.

I did some casual data reduction on it at the time with Stellarium---the idea was to start at the GPS position, then alter it interactively until the photo trail matched the Stellarium-rendered orbit as precisely as possible in cross-track.

In general, I needed to adjust the position by anywhere from 6 to 12 arcseconds to make the trails match. Resolution is quite high---if I had done proper modeling of the streak the internal uncertainty would have been well under 1 arcsec (maybe approaching 0.1 arcsec). So we can blame either the orbits or Stellarium's orbital model or mismatches between TEME and WGS/ITRF.

The satellite is "ADEOS Rocket", by the way (NORAD catalog number 24279).

Perhaps this rant could be sent to Seesat, but anyway:

Um, USSTRATCOM, could we have the orbits in some sort of civilized well-specified coordinate system? I'm not even sure I understand this TEME business, and I've tried reading the papers at celestrak.com. Must I maintain and propagate my own orbits for these objects using GPS as reference, which sort of defeats the whole navigation angle? Could we have proper uncertainties, with covariance, for the TLEs?

Cheers,

Peter

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