Ed Cannon requested search elements for this object: http://satobs.org/seesat/Aug-2002/0164.html Based on 11 proxy objects at similar altitudes, I estimate that the ndot/2 of Mike McCants' day 02115 elset should be multiplied by 0.6; here are the resulting search elements: USA 102 1.0 0.0 0.0 6.9 v 1 70001U 02115.12912960 .00010500 00000-0 67123-3 0 08 2 70001 105.0290 67.4212 0021000 276.6353 83.3646 15.08406176 02 I estimate the ndot/2 uncertainty to be 20 percent; this results in a prediction time uncertainty of about 26 minutes today. For the initial search, I suggest searching within the inner half of the uncertainty, say, +/- 13 min. It is not sufficient to simply stare at the predicted path for +/- 13 min; searchers must compensate for Earth's rotation during that interval, otherwise, the object is like to pass outside the field of view. A USA 102 pass predicted to culminate at 30 deg elevation in the east, becomes a 23 deg pass if the object is 13 min early, and a 42 deg pass if the object is 13 min late. The total elevation change of 19 deg is much wider than the field of view of binoculars. To minimize the effect of Earth's rotation, it is best to search at as a low an elevation as possible, at a low phase angle. The lower limit of the elevation depends upon the predicted brightness of the object, and the condition of the sky. The object must be bright enough to see; the sky must be sufficiently dark and clear to see the object plus some reference stars to be used in obtaining a position. Adjusting for Earth's rotation is not difficult, but it can be tedious. An easy method is to adjust the epoch by the desired time increment. For example, to compute the path of an object if it arrives 2 min early, subtract 2/1440 from the epoch. The above epoch would become 02115.12912960 - 2/1440 = 02115.12774071 . Happy hunting! Ted Molczan ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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