IOTA/IOTA-ES occultation update for (1812) Gilgamesh / TYC 5245-00981-1 event on 2012 Sep 30, 02:30 UT Visible from Europe, Venezuela, Colombia, Peru Summary ------- On 2012 Sep 30 UT, the 20 km diameter asteroid (1812) Gilgamesh will occult a 9.6 mag star in the constellation Aquarius for observers along a path across Europe, Venezuela, Colombia, Peru. In the case of an occultation, the combined light of the asteroid and the star will drop by 6.2 mag to 15.8 mag (the magnitude of the asteroid) for at most 1.8 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 24 * date and approx. time of event: 2012 Sep 30, 02:21 - 2012 Sep 30, 02:39 UT * geocentric midpoint of event [JD]: 2456200.60480833 * magnitude of target star: 9.6 * magnitude drop [mag]: 6.2 * estimated maximum duration [s]: 1.8 * Moon: 100 % sunlit, 22° distance * Sun: 158° distance * rough path description: Europe, Venezuela, Colombia, Peru The occultation path -------------------- * approximate projected width [km]: 20 * 1 sigma uncertainty interval [path widths]: +/- 2.81 * 1 sigma uncertainty interval [seconds]: +/- 6.4 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .051 +/- .035) * 1 sigma uncertainty ellipse (major, minor, PA): ( .052", .035", 79° ) * approx speed of asteroid's shadow [km/s]: 11.1833 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5245-00981-1 by 1812 Gilgamesh on 2012 Sep 30 Centre Star Star Sun Path Limits Error Limits E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " Longitude Longitude Longitude Longitude 23 11 35 49 0 0 2 21 34 2 261 -21 22 16 4 24 11 20 17 54 26 ... .. .. 15 19 21 48 0 0 2 21 38 7 256 -26 14 44 18 15 55 21 11 42 4 19 40 45 Latitude Latitude Latitude Latitude 14 0 0 47 47 0 2 21 40 8 255 -27 47 52 39 47 41 21 48 24 25 47 9 39 13 0 0 47 36 35 2 21 41 9 254 -28 47 42 15 47 30 56 48 14 7 46 59 8 12 0 0 47 25 41 2 21 42 9 253 -28 47 31 22 47 20 0 48 3 19 46 48 7 11 0 0 47 14 16 2 21 43 10 252 -29 47 19 58 47 8 35 47 52 2 46 36 36 10 0 0 47 2 21 2 21 44 11 252 -30 47 8 4 46 56 38 47 40 14 46 24 33 9 0 0 46 49 55 2 21 46 12 251 -30 46 55 39 46 44 11 47 27 55 46 12 0 8 0 0 46 36 58 2 21 47 12 250 -31 46 42 43 46 31 13 47 15 5 45 58 55 7 0 0 46 23 29 2 21 49 13 249 -32 46 29 16 46 17 43 47 1 45 45 45 19 6 0 0 46 9 29 2 21 50 14 249 -32 46 15 16 46 3 41 46 47 52 45 31 10 5 0 0 45 54 56 2 21 52 14 248 -33 46 0 45 45 49 7 46 33 28 45 16 29 4 0 0 45 39 51 2 21 54 15 247 -34 45 45 41 45 34 1 46 18 31 45 1 15 3 0 0 45 24 13 2 21 56 16 247 -34 45 30 4 45 18 21 46 3 2 44 45 28 2 0 0 45 8 1 2 21 58 17 246 -35 45 13 54 45 2 8 45 46 59 44 29 8 1 0 0 44 51 16 2 22 0 17 245 -36 44 57 10 44 45 22 45 30 24 44 12 13 0 0 0 44 33 57 2 22 3 18 244 -37 44 39 53 44 28 1 45 13 14 43 54 45 - 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2012 Sep 20 1 sigma uncertainty ellipse (major, minor, PA): 0.048, 0.028, 77° remarks: * orbital elements for (1812) Gilgamesh : Mean anomaly = 278.27908373 deg Arg. of pericenter = 264.52157932 deg Long. of node = 178.71118870 deg Inclination = 10.26259217 deg Eccentricity = 0.08271655 Semimajor axis = 3.00467760 AU Perihelion dist = 2.75614103 AU Mag: H = 11.44, G = 0.15 Epoch of elements : MJD 56200.10500000 TDT (2012 Sep 30.105) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Sep 30 1812 Gilgamesh 2h 30.9m UT 9.6 23 1 23.232- 4 22 21.55TYC 5245-00981-1 9.9 15.8 20 1.8 2.039 -1.395 -17.47 -61.6331 -4.368 139.77 -2.91 2.5154 -0.10296 0.12402 -4.83984 -4.05209 0.00208 0.00069 2000 276.3668392012 920.00000264.521579178.711189 10.2625920.08271655 3.0046776 2.756141011.3 5.00.15 RATE 1.8923750 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.052 0.035 79 3.81 0.038 0 0 3 4 056197.0020120930_0981-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 26, 21:50 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org