----- Original Message ----- Subject: Re: ISS saturn transit Hi Tom, > The main problem is that, without a high-speed camera a la Roland Stalder's 16 > August '03 solar transit, it'll just be pot luck as to how close you can > actually catch it to Saturn. Yes , I agreee , maximim speed I might be able to run would be about 30 fps. > Technically speaking, it appears that the angular diameter of the ISS will be > greater than that of Saturn, so if you do get it, it'll be an occultation (or > maybe an eclipse?) rather than a transit. True , but that only applies if I actually caught the station "full on" , I suspect if anything , I might just see a solar panel clip the rings. > ISS Transit is almost ready to go back on the air. My mother had a knee > replacement just before Christmas, so most of the "spare time" I thought I'd > have for program changes went up in smoke. Something I'd hoped to add- and may > still get around to it- are ISS Jupiter & Saturn encounters. Great stuff ( hope your mum is feeling better !) > One thing I've implemented is ray-tracing through the atmosphere. Actually, it > appears that such presumed precision only makes a difference of a few minutes of > arc, even at an elevation angle as low as about 1.5 degrees (and essentially no > difference at high elevations). And, likely as not, the imprecision in the TLE > state vector is generally likely to be much greater than the precision added by > carefully accounting for atmospheric refraction. Yes , we found this with the Mars encounter a couple of months ago. > I understand from Arnold Barmettler that he seems to be of the opinion that MCC > TLEs aren't very reliable after a day or so (from my limited experience, I'd > come to the opposite conclusion), so he only uses them for long-range > predictions; instead using fresh OIG TLEs for near-term predictions. (Just > today, I made a request to OIG for a "historic TLE" for the 16 August solar > transit, to compare with my MCC TLE prediction.) That would be interesting to do with my two consecutive transits of August 14 as it would provide quite a high degree of accuracy , having two full disk passes on video. http://www.satcom.freeserve.co.uk/1408.GIF http://www.satcom.freeserve.co.uk/iss1625.GIF > I'd suggest that, if possible, you also set up a camera with a time-lapse > exposure, so that it'll be possible to determine the prediction accuracy. Problem with that is that ISS will be in shadow , so a time lapse will show nothing but a very bright track , showing the movement of saturn.....the station will be invisible. I think the weather may well turn against me , but I was going to use Arnold's predictions to pinpoint location , simply sit on Saturn at hi magnification / 30 fps , and just hope something turned up :O) John. ( Odds conservatively estimated at one million to one ....he he ) ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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