On the dates you mentioned, the mean motion of Omid is nearing 16.04, which gives 90 minutes at that (55 d) inclination. You can also have 1-day repeat on 96 min (MM ~15), ~103 min (MM ~14) etc. Iridiums have a 3-day repeat (3*1440/43=100.465 min nodal), but the also further W. Other satellites have repeat patterns of the ground track, like China's Shenzhou in two days - every 31 orbit it passed over the landing area. For 90 degrees a 90 min nodal period object will pass at the same RA same time next day, and because of Earth's motion around the Sun this will be 1 degree further W on Earth's surface. "Sun-synchronous" satellites near 98 degrees can have passes at the same time AND altitude, if period is choosen correctly. ----- Original Message ----- ... > Because the shape of the Earth causes the node of the orbit > to precess, the passes seen on different days are further > to the west unless the inclation is 90 degrees. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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