The next launch window is from Apr 12 22:00 UTC to Apr 13 03:00 UTC. This message is for observers who may wish to search for whatever may reach orbit. Whether anything is actually intended to reach orbit remains unproven, but there is some supporting evidence, if taken at face value, e.g. orbit plots displayed on launch control consoles. For the announced mission type, Earth resource monitoring, common practice has been for the orbital plane to cross the equator south-bound about 10-10:30 AM local standard time, to provide optimal illumination. The Landsat and Spot satellites are among the satellites in such orbits. If North Korea intends to place its satellite near the orbital plane of those satellites, then the launch will occur in the vicinity of 02:00 UTC, +/- say 1 h. Therefore, I believe that the most probable launch time during each day of the launch campaign is between 01:00 UTC and 03:00 UTC - the final couple of hours of the window. The following search TLE is based on launch on Apr 13 at 01:00 UTC: 1 79801U 12104.04861111 .00000000 00000-0 00000-0 0 08 2 79801 97.4000 159.1189 0002000 0.0000 159.7600 15.21000000 00 The RAAN and mean anomaly are derived from information provided by Bob Christy, which he derived from analysis of an image of a 3D representation of the orbit relative the Earth, from news video of the launch control centre. Practically, the uncertainty in the plane could be 1 deg. Prediction time uncertainty 24 h after launch is at least several minutes. The above TLE indicates evening visibility for observers north of about 35 N. The southerly latitude limit moves north as the launch time moves later. I offer the following advice regarding expected visual brightness. Please note that all magnitudes I provide should be taken to be long-term mean values, with uncertainty on any given pass of at least +/- 2 magnitudes. Two objects would be expected to reach orbit. The payload, Kwangmyongsong-3, reportedly has dimensions 1.372 m X 0.732 m X 0.602 m (Jim Oberg via NSF). I estimate standard visual magnitude of about 8.4 (1000 km range, 90 deg phase angle). It may reach magnitude 6 or 7 at optimal range and phase angle, which is well within reach of binoculars and small telescopes. The third stage dimensions are about 4.3 m x 1.2 m (scaled from a photo). I estimate standard visual magnitude of about 6.9 (1000 km range, 90 deg phase angle). It may reach magnitude 4 or 5 at optimal range and phase angle, which would be visible to the un-aided eye. The payload reportedly carries UHF and X-band transmitters. If anyone has reliable information on its precise radio transmission frequencies, or advice on the most likely frequency ranges, please feel free to share via the list. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
This archive was generated by hypermail 2b29 : Thu Apr 12 2012 - 15:39:02 UTC