The "speed" of the stars is not the issue - they move only because of Earth rotation. But the Earth's surface moves at up to .463 km/s (equator) and a typical LEO at 7.5 km/s - a ratio of only 1:16 A higher satellite is slower (physically), put the rotation speed of a point above a fixed longitude at e.g. 12000 km altitude is 1.33 km/s, so there is a drastic influence, if the satellite is not moving straight west-east. Rob Matson's SkyMap allows you to plot either the true motion among stars or the apparent alt-az motion. I have combined the pairs for an Iridium and a MEO satellite. I made the alt-az tracks red, the RA-Dec tracks blue. /Björn Gimle >A typical field of view is 1 degree. It would take 4 minutes for stars > to >cross from one side to the other. A typical LEO would take 1 second. > >Your field of view may be larger but the point is the ratio of > velocities is >about 300 to 1. Even if the LEO is perpendicular the arctangent of > 1/300 is >.2 degrees. Probably too small to measure. > >You need a satellite much higher that takes more like 1 minute to > cross the >field of view. Of course these are very faint. -------------- next part -------------- A non-text attachment was scrubbed... Name: 61_Eq_Az.gif Type: image/gif Size: 15223 bytes Desc: not available Url : http://mailman.satobs.org/mailman/private/seesat-l/attachments/20110313/589d390a/attachment.gif -------------- next part -------------- A non-text attachment was scrubbed... Name: Ir_Eq_Az.gif Type: image/gif Size: 17765 bytes Desc: not available Url : http://mailman.satobs.org/mailman/private/seesat-l/attachments/20110313/589d390a/attachment-0001.gif _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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