The lowest elevation pass I have on file Tom is that of Aug 29 2003 ( had forgotten about it ) The sun was at 15 degs , and ISS had an angular diameter of just 4.1" at a range of 1125km I'd be surprised if you could get any useable results below that elevation as you would need a near full disk image , and the station would be almost invisible. A smaller FOV could obviously be used , but then that would defeat the object as only a tiny portion of the solar disk would be in frame. John. ----- Original Message ----- From: "Thomas Fly" <tfly@alumni.caltech.edu> To: "Matson, Robert" <ROBERT.D.MATSON@saic.com>; "SeeSat-L" <SeeSat-L@satobs.org> Sent: Friday, June 04, 2004 5:33 PM Subject: Re: accuracy of ISS / Venus transit track > Robert Matson wrote: > > Just wanted to chime in that Tom is absolutely right > > Hi Robert- I entered the following transit location into CalSKY: > > A - seconds elapsed since "Contact 1," at 5:13:29 UTC > B - UTC time (June 8) > > C - elevation angle of the ISS/Venus > D - azimuth angle of the ISS ( + is East from North; - is W from N) > E - range (miles) > > F - latitude for observing the transit > G - longitude > > H - sun elevation angle > I - sun/Venus separation angle > > A---- B------- C--- D----- E--- F------- G-------- H---- I---- > 7762 7:22:51 0.9 -64.5 1319 27.5991 171.1298 0.5 0.2 > > which appears to give an "unrefracted" answer back, showing the ISS passing > about 2' of arc above Venus: > > Tuesday 8 June 2004 > Observer SiteUser Site > WGS84: Lon: +171d07m47.3s Lat: +27d35m56.8s Alt: -6m > 7h22m50.97sISSMay cross the disk of Venus. Separation: 0.03d Position Angle: > 117.9d > Angular Velocity: 6.5'/s Angular diameter: 8.7" size: 73.0m x 44.5m x 27.5m > Satellite at az: 295.5d WNW h: 1.0d dist: 2122.7 km mag=13.1m -5.7 > > I hope someday to capture a transit of the ISS across a rising/setting Sun or > Moon- though at that distance & seeing, the ISS is likely only to be a small, > indistinct blob- otherwise, the effect of atmospheric ray-bending is just a > small technical point ;-) > > ------------------------------------------------------------------------- > Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: > http://www.satobs.org/seesat/seesatindex.html > > ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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