IOTA/IOTA-ES occultation update for (191) Kolga / UCAC2 36256331 event on 2012 Aug 31, 05:30 UT Visible from Africa Summary ------- On 2012 Aug 31 UT, the 101 km diameter asteroid (191) Kolga will occult a 11.4 mag star in the constellation Orion for observers along a path across Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.3 mag to 14.6 mag (the magnitude of the asteroid) for at most 3.4 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: 79 * date and approx. time of event: 2012 Aug 31, 05:26 - 2012 Aug 31, 05:28 UT * geocentric midpoint of event [JD]: 2456170.72944167 * magnitude of target star: 11.4 * magnitude drop [mag]: 3.3 * estimated maximum duration [s]: 3.4 * Moon: 100 % sunlit, 121° distance * Sun: 65° distance * rough path description: Africa The occultation path -------------------- * approximate projected width [km]: 102 * 1 sigma uncertainty interval [path widths]: +/- 0.69 * 1 sigma uncertainty interval [seconds]: +/- 2.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .036 +/- .032) * 1 sigma uncertainty ellipse (major, minor, PA): ( .036", .032", 89° ) * approx speed of asteroid's shadow [km/s]: 29.7825 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 36256331 by 191 Kolga on 2012 Aug 31 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 ' " Latitude Latitude Latitude Latitude - 57 0 0 2 13 51 5 26 51 1 77 -63 1 45 35 2 42 5 1 6 32 3 21 2 - 56 0 0 2 27 32 5 26 51 2 77 -62 1 59 17 2 55 46 1 20 15 3 34 40 - 55 0 0 2 41 3 5 26 51 3 77 -61 2 12 49 3 9 16 1 33 49 3 48 9 - 54 0 0 2 54 24 5 26 52 4 77 -60 2 26 11 3 22 35 1 47 12 4 1 28 - 53 0 0 3 7 34 5 26 52 5 77 -59 2 39 22 3 35 45 2 0 24 4 14 35 - 52 0 0 3 20 34 5 26 52 6 77 -58 2 52 23 3 48 43 2 13 26 4 27 32 - 51 0 0 3 33 22 5 26 53 7 77 -57 3 5 12 4 1 30 2 26 17 4 40 18 - 50 0 0 3 45 59 5 26 53 8 77 -56 3 17 50 4 14 7 2 38 57 4 52 53 - 49 0 0 3 58 25 5 26 54 9 77 -55 3 30 17 4 26 31 2 51 25 5 5 16 - 48 0 0 4 10 39 5 26 55 10 78 -54 3 42 32 4 38 44 3 3 42 5 17 28 - 47 0 0 4 22 41 5 26 55 11 78 -53 3 54 35 4 50 45 3 15 46 5 29 27 - 46 0 0 4 34 31 5 26 56 12 78 -52 4 6 26 5 2 34 3 27 39 5 41 15 - 45 0 0 4 46 8 5 26 57 13 78 -51 4 18 5 5 14 10 3 39 19 5 52 49 - 44 0 0 4 57 33 5 26 58 14 78 -50 4 29 31 5 25 34 3 50 46 6 4 12 - 43 0 0 5 8 45 5 26 59 15 78 -49 4 40 44 5 36 45 4 2 1 6 15 22 - 42 0 0 5 19 45 5 27 0 16 78 -48 4 51 44 5 47 44 4 13 3 6 26 18 - 41 0 0 5 30 31 5 27 1 17 78 -47 5 2 31 5 58 28 4 23 51 6 37 2 - 40 0 0 5 41 3 5 27 2 18 78 -46 5 13 5 6 9 0 4 34 26 6 47 32 - 39 0 0 5 51 22 5 27 3 19 78 -45 5 23 25 6 19 18 4 44 48 6 57 49 - 38 0 0 6 1 28 5 27 5 20 78 -44 5 33 32 6 29 23 4 54 56 7 7 51 - 37 0 0 6 11 19 5 27 6 21 78 -43 5 43 24 6 39 13 5 4 50 7 17 41 - 36 0 0 6 20 57 5 27 7 22 79 -42 5 53 3 6 48 50 5 14 30 7 27 16 - 35 0 0 6 30 20 5 27 9 23 79 -41 6 2 27 6 58 12 5 23 56 7 36 37 - 34 0 0 6 39 29 5 27 10 24 79 -40 6 11 37 7 7 20 5 33 7 7 45 43 - 33 0 0 6 48 24 5 27 12 25 79 -39 6 20 32 7 16 13 5 42 4 7 54 35 - 32 0 0 6 57 3 5 27 14 26 79 -38 6 29 13 7 24 52 5 50 46 8 3 13 - 31 0 0 7 5 28 5 27 15 27 79 -37 6 37 39 7 33 16 5 59 13 8 11 35 - 30 0 0 7 13 38 5 27 17 28 79 -36 6 45 50 7 41 25 6 7 25 8 19 43 - 29 0 0 7 21 33 5 27 19 29 79 -35 6 53 46 7 49 19 6 15 22 8 27 36 - 28 0 0 7 29 13 5 27 21 30 79 -34 7 1 26 7 56 58 6 23 4 8 35 14 - 27 0 0 7 36 37 5 27 23 31 79 -33 7 8 52 8 4 22 6 30 30 8 42 36 - 26 0 0 7 43 46 5 27 25 32 79 -32 7 16 2 8 11 30 6 37 42 8 49 43 - 25 0 0 7 50 40 5 27 27 33 80 -31 7 22 56 8 18 23 6 44 37 8 56 35 - 24 0 0 7 57 18 5 27 29 34 80 -30 7 29 35 8 25 0 6 51 17 9 3 11 - 23 0 0 8 3 40 5 27 31 35 80 -29 7 35 57 8 31 21 6 57 41 9 9 31 - 22 0 0 8 9 46 5 27 33 36 80 -28 7 42 4 8 37 26 7 3 49 9 15 35 - 21 0 0 8 15 36 5 27 36 37 80 -27 7 47 55 8 43 16 7 9 40 9 21 24 - 20 0 0 8 21 11 5 27 38 38 80 -26 7 53 30 8 48 50 7 15 16 9 26 57 - 19 0 0 8 26 29 5 27 40 39 80 -25 7 58 49 8 54 7 7 20 36 9 32 13 - 18 0 0 8 31 31 5 27 43 40 80 -24 8 3 52 8 59 8 7 25 39 9 37 14 - 17 0 0 8 36 16 5 27 45 41 80 -23 8 8 38 9 3 53 7 30 27 9 41 58 - 16 0 0 8 40 46 5 27 48 42 80 -22 8 13 8 9 8 22 7 34 57 9 46 26 - 15 0 0 8 44 58 5 27 50 43 80 -21 8 17 21 9 12 34 7 39 11 9 50 37 - 14 0 0 8 48 55 5 27 53 44 80 -20 8 21 18 9 16 30 7 43 9 9 54 33 - 13 0 0 8 52 35 5 27 56 45 80 -19 8 24 58 9 20 10 7 46 50 9 58 11 - 12 0 0 8 55 58 5 27 58 46 80 -18 8 28 22 9 23 32 7 50 14 10 1 34 - 11 0 0 8 59 4 5 28 1 47 80 -17 8 31 29 9 26 39 7 53 22 10 4 39 - 10 0 0 9 1 54 5 28 4 48 81 -16 8 34 19 9 29 28 7 56 12 10 7 28 - 9 0 0 9 4 27 5 28 7 49 81 -15 8 36 53 9 32 1 7 58 46 10 10 1 - 8 0 0 9 6 44 5 28 10 50 81 -14 8 39 9 9 34 17 8 1 3 10 12 16 - 7 0 0 9 8 43 5 28 12 51 81 -13 8 41 9 9 36 16 8 3 3 10 14 15 - 6 0 0 9 10 26 5 28 15 52 81 -12 8 42 52 9 37 59 8 4 46 10 15 57 - 5 0 0 9 11 52 5 28 18 53 81 -11 8 44 18 9 39 24 8 6 13 10 17 23 - 4 0 0 9 13 0 5 28 21 54 80 -10 8 45 27 9 40 33 8 7 22 10 18 31 - 3 0 0 9 13 52 5 28 24 55 80 -9 8 46 19 9 41 25 8 8 14 10 19 23 - 2 0 0 9 14 27 5 28 28 56 80 -8 8 46 54 9 41 59 8 8 49 10 19 57 - 1 0 0 9 14 45 5 28 31 57 80 -7 8 47 12 9 42 17 8 9 7 10 20 15 0 0 0 9 14 46 5 28 34 58 80 -6 8 47 13 9 42 18 8 9 8 10 20 16 1 0 0 9 14 30 5 28 37 59 80 -5 8 46 56 9 42 2 8 8 52 10 20 0 2 0 0 9 13 57 5 28 40 60 80 -4 8 46 23 9 41 29 8 8 19 10 19 27 3 0 0 9 13 7 5 28 44 61 80 -3 8 45 33 9 40 39 8 7 28 10 18 38 4 0 0 9 12 0 5 28 47 62 79 -2 8 44 26 9 39 33 8 6 21 10 17 31 5 0 0 9 10 36 5 28 50 63 79 -1 8 43 2 9 38 9 8 4 56 10 16 7 6 0 0 9 8 55 5 28 54 64 79 0 8 41 20 9 36 28 8 3 15 10 14 27 Uncertainty in time = +/- 3 secs Prediction of 2012 Jul 8.0 Data for the target star ------------------------ * name: UCAC2 36256331 * constellation : Orion * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 15 18.8590 DE: +12 58 59.866 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .032, .031 ) * V mag [mag]: 11.4 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (191) Kolga approx. diameter [km]: 101 approx. diameter ["]: .047 distance from Earth [AU]: 2.97400 * orbital information: orbit source: Preston date of fit: 2012 Jul 08 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1164 number of rejected observations: 95 time covered by the observations: 1902 Jul 09 - 2012 Jan 04 1 sigma uncertainty ellipse (major, minor, PA): 0.015, 0.009, 87° remarks: * orbital elements for (191) Kolga : Mean anomaly = 38.88632984 deg Arg. of pericenter = 228.15395624 deg Long. of node = 159.37424498 deg Inclination = 11.50062370 deg Eccentricity = 0.09157795 Semimajor axis = 2.89707807 AU Perihelion dist = 2.63176960 AU Mag: H = 8.90, G = 0.15 Epoch of elements : MJD 56170.22900000 TDT (2012 Aug 31.229) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 31 191 Kolga 5h 30.4m UT 11.4 6 15 18.859 12 58 59.87UCAC2 36256331 0.0 14.6 101 3.4 2.974 3.366 -7.05 31.4264 12.985 97.47 8.48 5.5066 -0.01640 -0.10500 16.64038 -2.38232 -0.00503 -0.00030 2000 38.8405582012 831.00000228.153956159.374245 11.5006240.09157795 2.8970781 2.6317696 9.1 5.00.15 RATE 1.9987740 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.036 0.032 89 1.69 0.032 0 0 0-4 056116.0020120831_256331 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 08, 00:18 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org