--- Patrick Wiggins <paw@trilobyte.net> wrote:
But I've yet to receive a [an ISS transit] report where any of the points corresponded with a convenient location to set up a scope. Up to now I've used a spread sheet to interpolate between the points and then used a site on the web to plot the data on a map.
Patrick, If I'm reading your post correctly, I just wanted to say that's absolutely brillant and is an original tool for making photographs of ISS transits of the Sun and Moon. One of the limitations of IIS tracking on heavens-above and CalSky with respect to ISS transits of the Sun and Moon is that you have to put your geographic position in and then search for those times when the ISS and the Moon and/or Sun will be aligned with your OP. At most you might get two or three occurrences per year. Like a reverse version of the parable about Mohammed and the mountain, I usually plug in my geographical position into CalSky and try to pull out the one or two times a year that the ISS (the mountain) will align with the Moon and/or Sun at my OP. One of the painfully obvious parts of the Stardust reentry was just how sensitive satellite observing is to geographic position. When you were at the Wendover Airport during the reentry, you saw Stardust from the side. I was 30 miles south and saw it travel on an East-West line straight-overhead. The same principal applies to ISS overpasses, althought the ISS is at a higher altitude. CalSky gives for visible ISS overpasses, a separate geographic latitude and longitude ground track. In theory, you can take the predicted ground track of a near overpass, the satellite's altitude, and the altitude and azimuth of the Sun or Moon during the transit, and then solve a spherical right triangle to find an ~approx. 1/2 degree wide swath at a nearby geographical location that you can drive to see a transit. So, like Mohammed, you can go to the mountain, that is drive 30-60 miles north or south, and watch an ISS transit of the Sun or Moon that will not be revealed by CalSky or heavens-above. This technique would greatly increase the number of opportunities to photo ISS Sun/Moon transits during a year. I'm guessing that you have built some variant of the Stardust reentry track calculation spreadsheet (prepared by a professional astronomer) that you sent me in January. Anyway, if so, what you have done is pretty original and amazing. That observing technique would greatly increase the number of opportunities per year one could photograph an ISS transit of the Sun and/or Moon. I know of no other amateur who has developed anything similar. To wrap up - 1) You have strong astro kung-fu. -:) 2) Your astro kung-fu is much stronger than my asto kung-fu. -:) 3) I bow before your superior astro kung-fu. -:) 4) After you get bored milking your spreadsheet for as many ISS transits photos as you can make, you should send your observing-reduction technique off to S&T in an article. (Really). - Canopus56 P.S. - If I have misinterpreted what you are up to, I apologize. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com