By using the data received from Ted this morning I included positions also for the phase following the second burn. The program can now show the spacecraft positions from launch to the heliocentric orbit, for a total of about 30 hours. (The ground track now is equivalent to the one published in the project's web site) I have also expanded the program panel in order to show the spacecraft topocentric coordinates DEC and RA, (J2000.0) along with the value of the visual Magnitude according to the estimation of Ted. This should allow users to autonomously generate quite accurate predictions, before asking to Ted. Just change the time with the keys s,S,m,M,h,H to obtain the position at the desired time. The link is not changed. However I report this new one that shows also the whole ground track: http://tinyurl.com/VSFT-Phobos-Vector-30h Best Regards, Simone >----Messaggio originale---- >Da: ssl3molcz@rogers.com >Data: 7-nov-2011 6.06 >A: <seesat-l@satobs.org> >Ogg: Phobos-Grunt - visibility from Europe and N. America > >As everyone may know, Phobos-Grunt is scheduled for launch on 2011 Nov 08 at 20:16:03 UTC, from Baikonur; and in >response to a request by the project, observers in South America are preparing to attempt observations of the two engine >burns that will propel the spacecraft into heliocentric orbit. > >What everyone may not know, is that soon after it enters heliocentric orbit, the spacecraft will exit eclipse and >quickly become visible to observers with small telescopes in large portions of Europe and Africa and parts of eastern >North America. > >The project's web site offers the following plot of the ground track, with altitude in kilometres at various points: > >http://phobos.cosmos.ru/uploads/pics/ground_track_01.jpg > >Exit from eclipse is predicted for 2011 Nov 09 at 01:33:48 UTC, less than 14 min after the burn into heliocentric orbit. >At that point, the spacecraft will be about 5600 km over 46.9 N, 12.8 W, and climbing rapidly as it heads toward The >English Channel. Europe will have a superb view, but at the same time it will reach a respectable elevation for portions >of the east of coast of North America, culminating near eclipse-exit. For example, at eclipse-exit from St. John's, >Newfoundland, it will be near elevation 39 deg; from Halifax, Nova Scotia it will be near 27 deg; from Boston ~19 deg, >and from New York City ~16 deg. > >Over the next several hours, it will loop around Eastern Europe while climbing to nearly 100,000 km, and then head >toward N. America. > >JPL's Horizon's web site will provide ephemerides once the spacecraft reaches its LEO parking orbit, about 11 min after >launch. Observer's should regard those ephemerides as definitive, but I have created an ephemeris for use in the >interim, to enable observers to evaluate their prospects of seeing the object, and to make preliminary plans. It is >similar to the one that covers the two engine burns over South America, that I announced a few days ago. > >The heliocentric orbit cannot be represented as a TLE, so I have extracted state vectors from the SPICE trajectory file >published on the project's web site, and created a spreadsheet to compute topocentric coordinates. The spreadsheet >and/or a custom ephemeris pdf generated using it, is available upon request. Please e-mail me off-list. If requesting >the pdf, please include your precise latitude, longitude and height above mean sea level. > >Based on drawings, I estimate that the spacecraft is about 5 m long, with diameter ranging from 2 m at the top to 3.4 m >at the base. That is sufficiently large for it to reach mag 8 or 9 for those closest to eclipse-exit, and mag 13-14 as >it passes geo-synchronous altitude. > >The ephemeris spreadsheet should be fairly accurate. The state vectors are at 5 min intervals in the SPICE files, which >is too coarse until about 02:00 UTC, so I interpolated each component of the state vector at 1 min intervals, by means >of a 4th order polynomial least squares fit, which appears to have resulted in very little degradation. > >The ephemeris includes the brief eclipsed phase after the final burn, but it is clearly marked, so should not create >confusion. > >I do not know whether the project would value positional observations during the early heliocentric phase. I will >attempt to find out, and will update the list when/if I learn more. > >Ted Molczan > > >_______________________________________________ >Seesat-l mailing list >http://mailman.satobs.org/mailman/listinfo/seesat-l > _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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