Log, May 2, 2003

No people. Earlier in the day, a Cub Scout leader sent me an e-mail saying that they were canceling the planned trip to FDO tonight. I concurred saying that I didn't hold out much hope. So I got a chance to try out the slashed-circle symbol over the closed and shutter image of our dome. The night bore me out. We had heavy clouds until 9PM. About then a few very bright objects like Jupiter could be faintly seen, but things still weren't good. The cloud shield had drifted east but it was still offering chances to rain. Sigh....

I've been experimenting with some new software that will allow us to track the slower moving satellites with our telescope. Near Earth satellites move much too rapidly for our telescope. They will cross the opening of the dome in a relatively few seconds, barely allowing anyone a glimpse. Worse yet they move faster than 4 degrees per second, the telescope's maximum safe slewing rate. They are out.

Geo-synchronous satellites stay put very nicely, but they are indistinguishable from stars. Although they lie directly above the Earth's Equator, they appear below the celestial Equator (due to a geometric thing-a-mabob called parallax).

A number of polar satellites use middle altitude between near Earth orbit (those less than 400 miles up) and geo-synchronous orbit at 23,000 miles. Two of the most interesting of these are the Global Positioning Satellites (that give your GPS units their positions)] and the Iridium communication satellites. I've been able to import the orbits for the GPS network and I've been simulating tracking of them using the software. Looks exciting and possible. They should be bright enough to see fairly well too.

-Les Coleman

Leslie Coleman
Leslie Coleman
Entry Date:
May 2, 2003
Published Under:
Leslie Coleman's Log
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