The launch window is from Apr 22, 23:52 UTC to Apr 23, 00:01 UTC. I estimate that the orbital inclination will be about 33.5 deg. My guess is that the altitude will be about 300 km, but I have produced search elements spanning 200 km to 500 km. Generating ephemerides for each elset, and plotting them on a star chart, will facilitate searching. The elements are based on launch at the start of the window. The final three digits of the pseudo-catalogue number denote the altitude in kilometres. 1 99200U 10113.03803170 .01058582 00000-0 25000-3 0 0 2 99200 33.4741 4.1001 0001000 21.5920 338.4841 16.28500000 0 1 99300U 10113.03918168 .00087351 00000-0 25000-3 0 00 2 99300 33.4741 4.2001 0001000 21.5920 338.4830 15.92000000 08 1 99400U 10113.04039649 .00018739 00000-0 25000-3 0 04 2 99400 33.4741 4.3001 0001000 21.5920 338.4820 15.57000000 00 1 99500U 10113.04164630 .00006048 00000-0 25000-3 0 04 2 99500 33.4741 4.5000 0001000 21.5920 338.4809 15.23000000 02 I would not be surprised if the inclination differed by a degree or two from the above, more likely higher than lower. During the first few hours after the launch, the altitude uncertainty is likely to have the greatest overall effect on predicted time and track uncertainty. Based on the object's dimensions, I estimate that its standard visual magnitude will be between 3 and 5 (1000 km, 90 deg phase angle). On launch day, northern hemisphere observers well south of about 35 N will have visibility near the start of civil twilight, so the sky will be fairly bright. The highest orbit would be visible at latitudes a bit greater than 35 N. Southern hemisphere observers near 35 S will have morning visibility. Searches at high elevation above the horizon should be conducted with the unaided eye. Searches at low elevation may benefit from the use of binoculars with a wide field of view, e.g. 7x50s. Regardless of the mode, it would be wise to avoid tunnel vision, and instead scan across the field defined by the various search elements, looking for objects moving in the correct direction. To avoid reporting the wrong object, consider running predictions for bright known objects that may pass through the search area at the relevant times. Heavens-Above and CalSky are among the web services that provide such predictions. Accurate observations of time and position will help to determine the orbit. The more accurate the better, but even distant appulses would be useful. For example, "passed 4 deg below star X, at time y". Timing accuracy of a few seconds would be helpful. If the object is observed to enter eclipse, the location and time would be useful information. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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