I received this request from recently. Given the .5 to 1km accuracy of the SGPD4 model I think its impossible with TLEs. What accuracy can one expect if one modelled the atmosphere with the public domain models and numerically integrated the equations of motion using the daily initial conditions provided by NASA? I also reminded him that the ISS may be bigger than his FOV (24by 24 arc seconds!! ===================================================== I have an independent question regarding satellites: Is there a way to obtain ephemerides for the ISS with arcsecond-precision via an online-tool or with freely available software? The reason I am asking is that I tried to image the ISS during my last observing run at Calar Alto with the 2.2m telescope and a high-speed camera during dawn. (My personal definition of dawn is: the time between taking flatfields and doing 'real' science where nobody cares what you are using with the telescope for...) The camera has an FOV of 24arcsec, delivers 34 frames per second, and can easily acquire several 10000 of them. I got some TLEs - I think from heavesabove.com - and fed them into EasySky to get a topocentric ephemeris, pointed the telescope to some coordinates where the ISS *should* pass, started the acqusition and waited. At least on one frame it should have been visible, but I had no luck. I guess that either the TLEs were bad or too old (it was during the time the Shuttle was docked) or EasySky does not work with the required precision. Can you recommend me any TLE sources and software for the next time? ============================================================= Tony Beresford Cospar 8597 , -34.9638, 138.6333E ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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