In my wandering in old publications, I got the sept/oct 1961 issue of "Coelum" an astronomy magazine published in Italy by the Bologna astronomical observatory. I found an article in which was suggested to time the eclipse of the satellite caused by the shadow of the Earth. To take in account the movement of about 1 deg/day of the umbral cone of the earth, for satellite with a period of about 2 hours and moving in direct mode (the article was dealing with Echo 1 sat), the suggestion is to subtract 2 sec per revolution. The timing over 1 year gives for Echo sat the period decreasing from 118.28 min (31 aug 1960) to 116.9 min (15 aug 1961). I'd like to perform on my own such an observation. A big advantage is that you have not to build any instrument - need only a binoculars and stopwatch. From observing satellite vanishing in the earth shadow, I guess you can time the swicth-off-time with an approximantion of some seconds, the observation program on a single satellite must be run for, say, 1 year at least. Probably it would be better to deal with circular orbit satellites (to neglect the variation af the argument of perigee) of known inclination (to calculate the time difference of the eclipsing time in second/orbit due to westward precession and earth revolution). Some suggestions about ? Probably I can simulate the activity with my Satspy software, to plan the observing sessions during the year. The sake of the game ? To "touch" the space from my backyard ... Greetings Paolo Morini ----------------------------------------------------------------- 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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