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See Discovery/ISS in formation after un-docking
Observers at certain latitudes have the opportunity to see Discovery and ISS
in close formation, after they un-dock early Saturday, 2005 Aug 6, at 07:22 UTC (3:22 AM EDT). Observers between roughly 10 N and 40 N latitude, will have morning visibility. Observers between roughly 20 S and 55 S latitude, will have evening visibility. The best passes will occur near the middle of those ranges; marginal passes will occur near their extremes. Here is some additional information for U.S. observers: Saturday August 6 About 09:15 UTC (5:15 AM EDT), Florida will have a low pass, during which the spacecraft are predicted to be about 1 km apart. Binoculars likely will be required to resolve them as separate objects. About 10:50 UTC (5:50 AM CDT), Alabama, Arkansas, Louisiana, Mississippi and Texas, will have a good to excellent pass. The spacecraft are predicted to be about 7 km apart, resulting in angular separation of up to 1 deg (if seen directly overhead). About 12:21 UTC (5:21 PDT), Arizona and Southern California will have a good pass. The spacecraft are predicted to be about 29 km apart. Sunday August 7 On August 7, there will be good to excellent passes of most southern U.S. states. The spacecraft will be about 250 km apart, or about one half minute of flight time. For a quick way to check on visibility where you live, I recommend this page operated by NASA, which lists major cities around the world: http://spaceflight1.nasa.gov/realdat...ties/index.cgi For detailed sky-charts and ground tracks, try Heavens-Above or CalSky: http://www.heavens-above.com/ http://www.calsky.com/cs.cgi/Satellites/4 NOTE: it is recommended to run your predictions for ISS, because it is not expected to manoeuvre over the next few days. Just be aware that Discovery will lead ISS by the distances discussed above. For those who prefer to make their own computations, I have appended NASA's predicted orbital elements that take into account Discovery's manoeuvres to separate from ISS. Clear skies! Ted Molczan Predicted 2-line orbital elements I have extracted and appended the key elsets for those who wish to evaluate their prospects to observe the spacecraft in close proximity to one another. The elsets below were downloaded on 2005 Aug 05 UTC, from the following NASA site (for shuttle hit the red icon; for ISS, hit the green one): http://spaceflight1.nasa.gov/realdat...nts/index.html 1. 2005 Aug 06 08:39 - 09:07 UTC (period between separation burn #1 and burn #2) Discovery 1 28775U 05026A 05218.38141706 .00016071 00000-0 12697-3 0 9025 2 28775 51.6421 3.8986 0001995 216.2554 143.8473 15.71511439 1719 ISS 1 25544U 98067A 05218.57218742 .00016071 00000-0 12697-3 0 9029 2 25544 51.6445 2.9206 0002067 222.2583 137.8420 15.71515070 23614 2. 2005 Aug 06, 09:07 UTC - Aug 07, 09:08 UTC (after separation burn #2) Discovery 1 28775U 05026A 05218.38141726 .00016071 00000-0 12697-3 0 9038 2 28775 51.6419 3.8976 0004124 192.2344 167.8719 15.72062763 1713 ISS 1 25544U 98067A 05218.57218742 .00016071 00000-0 12697-3 0 9029 2 25544 51.6445 2.9206 0002067 222.2583 137.8420 15.71515070 23614 3. 2005 Aug 07, 09:09 UTC to Discovery's de-orbit on Aug 08 Discovery 1 28775U 05026A 05219.39849213 .00016071 00000-0 12697-3 0 9047 2 28775 51.6417 358.6892 0004123 193.8333 166.2716 15.72087121 1875 ISS 1 25544U 98067A 05219.58962826 .00016071 00000-0 12697-3 0 9031 2 25544 51.6448 357.7150 0002096 224.7886 135.3107 15.71511262 23772 |
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Ted Molczan wrote:
Observers at certain latitudes have the opportunity to see Discovery and ISS in close formation, after they un-dock early Saturday, 2005 Aug 6, at 07:22 UTC (3:22 AM EDT). About 12:21 UTC (5:21 PDT), Arizona and Southern California will have a good pass. The spacecraft are predicted to be about 29 km apart. Ted, Thanks for the information. I will be watching from Phoenix Saturday morning. The sun will be only 5 degrees below the horizon, but I think the satellites will be bright enough. If I did my trig correctly (distance=512km, separation=29km), the two craft will be separated by just over 3 degrees when they are at their highest altitude. Tom |
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