hello george I watched ISS pass chicago just 12 degrees off the sw horizon over antares (it passed over antares [which wasn't visible] at approximately 01:44:10 UTC 19 sept) on the orbit previous to your predicted pass, through scattered clouds. it appeared to be exactly on time with the HA prediction chart. so unless a boost occured between my sighting of it and your predicted pass, you should have seen it near vega just at 03:16:00 UTC 19 sept. the only reasons I can come up with as to why you may have missed it: 1. your watch: was it accurate? I synch mine to the tones (which you can hear by dialing WWVH broadcast (808) 335-4363) fairly regulary... I've found that just a little bit of error can cause you to miss an object," especially the dimmer ones. 2. could one of the airliners you observed have been ISS? if you don't see a strobe, it's not an aircraft. many times i have waited for ISS I have seen it and then said to myself, " no, wait, that's an aircraft, only to determine after a few more seconds that it really was ISS. if this was your first attempt to observe ISS it would have been easy and excusable to mistake it for a jet. 3. light pollution/cloudcover/atmospheric contamination: I doubt it could have been light pollution because i have seen ISS go past from the middle of manhattan and also downtown chicago, and those are among the worst light-polluted places on the planet. cloudcover? it seems unlikely, if you could see vega and the moon you probably should have seen ISS. perhaps it was some freak combination of the two. since the ISS entered the shadow almost at the zenith, it's possible that it slipped between some off-shore cloudiness and the point where it entered the shadow at just the moment when you were distracted by the chopper et cetera. it only takes a moment's distraction sometimes. also, with LA being between you and the lower part of the pass, it could have been blocked until it got above 35 or 40 degrees elevation by that pesky smog. were you able to observe cor caroli in canes venatici or alkaid in ursa major? I suggest you make your watch (if it isn't already) accurate to within 1 second and tomorrow night (tonight 19 sept PDT) at 19:06:28 PDT make sure you are looking directly at caph and schedar in cassiopeia. if at that time you are able to see the principal stars of cassiopeia, you will certainly see the station pass between those two suckers. if we find out it was boosted between my sighting and your failure to sight it, disregard all this... it appears that it was ready for a boost, look here: http://www.heavens-above.com/issheight.asp?lat=32.715&lng=-117.156&alt=26&loc=San+Diego&TZ=PST from what I am led to understand, data on HA is usually up to 3 days old. clear skies! stephan szyman chicago IL USA 41.6840N, 87.7000W; 188 msl 16/2005 12:42:57 P.M. Pacific Standard Time, Dinogeorge >writes: > >I realize that the mind slows a bit with age, but I believe I am still >capable of reading a satellite ephemeris and accompanying star chart on >which is >clearly printed that the ISS will appear in the NW on September 18, 2005 at >20:13 Pacific Daylight Time and will pass almost directly overhead in San >Diego, > California something like 3 minutes later, pretty bright at magnitude >-0.9. >After all, Vega is clearly marked on the chart and, by golly, IT was right >where it was supposed to be, almost directly overhead. The sky was clear, >the >moon was just rising a day past full (so I know where, say, EAST is), and >the >ISS? Well, the ISS was NOT THERE. > >I began watching shortly before 8 pm Sunday night, eyes glued to the NW, >11x80 binoculars strapped around my neck. When my watch said 8:15 and no >sign of >the ISS I began to wonder what was going on. I did spot a few airliners >and >a helicopter during my little vigil, and to amuse myself scanned the >moon's >face as it slowly climbed upward from the horizon. By 8:30 I decided that >I >had somehow misread the chart and that maybe I should re-emerge around >9:00 in >case the chart had given standard time by mistake rather than daylight >time. >Nope, no ISS at 9:15 either. By then evening clouds were gathering, but a >few >stars were still visible through the haze and I don't think I could have >missed something as bright as the ISS. > >I simply dunno what happened; something is definitely amiss with the >Heavens >Above website. The evening was rather a bust after that. > >The same chart says the ISS will pass over San Diego again from the NW on >Tuesday evening at about 7:30 pm, not quite as high or as bright. Will I >waste >more time looking then? > > ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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