IOTA/IOTA-ES occultation update for (11889) 1991 AH2 / HIP 93118 event on 2012 Aug 07, 19:34 UT Visible from SW Asia, Arabia, Africa Summary ------- On 2012 Aug 07 UT, the 13 km diameter asteroid (11889) 1991 AH2 will occult a 6.9 mag star in the constellation Sagittarius for observers along a path across SW Asia, Arabia, Africa. In the case of an occultation, the combined light of the asteroid and the star will drop by 8.6 mag to 15.5 mag (the magnitude of the asteroid) for at most 1.3 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: . The event at a glimpse ---------------------- * Rank: 11 * date and approx. time of event: 2012 Aug 07, 19:22 - 2012 Aug 07, 19:44 UT * geocentric midpoint of event [JD]: 2456147.31527083 * magnitude of target star: 6.9 * magnitude drop [mag]: 8.6 * estimated maximum duration [s]: 1.3 * Moon: 68 % sunlit, 100° distance * Sun: 148° distance * rough path description: SW Asia, Arabia, Africa Additional comments ------------------- 16" double star The occultation path -------------------- * approximate projected width [km]: 13 * 1 sigma uncertainty interval [path widths]: +/- 5.92 * 1 sigma uncertainty interval [seconds]: +/- 6.1 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .079 +/- .053) * 1 sigma uncertainty ellipse (major, minor, PA): ( .081", .051", 104° ) * approx speed of asteroid's shadow [km/s]: 9.4588 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 93118 by 11889 1991 AH2 on 2012 Aug 7 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 91 23 18 57 0 0 19 22 54 1 229 -15 91 13 18 91 33 19 89 16 40 ... .. .. 89 19 42 56 0 0 19 22 55 2 228 -16 89 10 14 89 29 11 87 19 39 91 23 5 Latitude Latitude Latitude Latitude 88 0 0 55 18 46 19 22 55 3 227 -17 55 23 37 55 13 54 56 21 11 54 16 34 87 0 0 54 46 20 19 22 56 4 226 -18 54 51 14 54 41 25 55 49 29 53 43 26 86 0 0 54 12 40 19 22 57 5 225 -19 54 17 38 54 7 42 55 16 33 53 9 3 85 0 0 53 37 44 19 22 57 5 224 -19 53 42 45 53 32 42 54 42 21 52 33 22 84 0 0 53 1 28 19 22 58 6 223 -20 53 6 33 52 56 23 54 6 52 51 56 22 83 0 0 52 23 51 19 23 0 7 223 -21 52 29 0 52 18 43 53 30 1 51 17 59 82 0 0 51 44 50 19 23 1 8 222 -22 51 50 2 51 39 38 52 51 47 50 38 12 81 0 0 51 4 22 19 23 3 9 221 -22 51 9 38 50 59 6 52 12 7 49 56 57 80 0 0 50 22 25 19 23 4 10 220 -23 50 27 44 50 17 5 51 30 58 49 14 12 79 0 0 49 38 55 19 23 6 11 220 -24 49 44 18 49 33 32 50 48 17 48 29 55 78 0 0 48 53 51 19 23 9 12 219 -25 48 59 18 48 48 24 50 4 2 47 44 2 77 0 0 48 7 10 19 23 11 13 218 -26 48 12 41 48 1 39 49 18 10 46 56 33 76 0 0 47 18 49 19 23 14 14 217 -27 47 24 24 47 13 14 48 30 39 46 7 24 75 0 0 46 28 47 19 23 17 15 217 -27 46 34 25 46 23 8 47 41 26 45 16 33 74 0 0 45 37 0 19 23 21 16 216 -28 45 42 43 45 31 18 46 50 29 44 23 58 73 0 0 44 43 28 19 23 25 17 215 -29 44 49 14 44 37 42 45 57 46 43 29 37 72 0 0 43 48 8 19 23 29 18 214 -30 43 53 57 43 42 18 45 3 14 42 33 30 71 0 0 42 50 58 19 23 33 20 214 -31 42 56 52 42 45 5 44 6 52 41 35 33 70 0 0 41 51 58 19 23 38 21 213 -32 41 57 55 41 46 1 43 8 39 40 35 47 69 0 0 40 51 6 19 23 44 22 212 -33 40 57 7 40 45 6 42 8 34 39 34 11 68 0 0 39 48 22 19 23 50 23 212 -34 39 54 26 39 42 18 41 6 35 38 30 43 67 0 0 38 43 46 19 23 56 25 211 -35 38 49 54 38 37 39 40 2 42 37 25 25 66 0 0 37 37 17 19 24 3 26 210 -36 37 43 28 37 31 7 38 56 55 36 18 16 65 0 0 36 28 57 19 24 10 27 210 -37 36 35 11 36 22 44 37 49 14 35 9 17 64 0 0 35 18 47 19 24 18 29 209 -38 35 25 4 35 12 30 36 39 42 33 58 30 63 0 0 34 6 48 19 24 26 30 209 -39 34 13 7 34 0 29 35 28 18 32 45 56 62 0 0 32 53 2 19 24 35 32 208 -40 32 59 24 32 46 40 34 15 5 31 31 38 61 0 0 31 37 33 19 24 45 33 207 -42 31 43 57 31 31 9 33 0 6 30 15 40 60 0 0 30 20 23 19 24 55 35 207 -43 30 26 50 30 13 57 31 43 24 28 58 4 59 0 0 29 1 38 19 25 6 36 206 -44 29 8 6 28 55 10 30 25 2 27 38 54 58 0 0 27 41 20 19 25 17 38 206 -45 27 47 50 27 34 50 29 5 6 26 18 16 57 0 0 26 19 36 19 25 29 39 205 -46 26 26 7 26 13 5 27 43 40 24 56 14 56 0 0 24 56 30 19 25 41 41 204 -47 25 3 3 24 49 58 26 20 49 23 32 55 55 0 0 23 32 10 19 25 54 43 204 -48 23 38 43 23 25 37 24 56 40 22 8 23 54 0 0 22 6 42 19 26 8 44 203 -49 22 13 15 22 0 8 23 31 19 20 42 47 53 0 0 20 40 12 19 26 22 46 203 -50 20 46 46 20 33 38 22 4 54 19 16 12 52 0 0 19 12 48 19 26 36 48 202 -51 19 19 22 19 6 14 20 37 31 17 48 47 51 0 0 17 44 38 19 26 52 49 201 -52 17 51 12 17 38 4 19 9 18 16 20 39 50 0 0 16 15 49 19 27 7 51 201 -52 16 22 23 16 9 15 17 40 24 14 51 56 49 0 0 14 46 30 19 27 24 53 200 -53 14 53 3 14 39 57 16 10 56 13 22 45 48 0 0 13 16 49 19 27 40 54 199 -54 13 23 21 13 10 17 14 41 3 11 53 15 47 0 0 11 46 54 19 27 57 56 199 -54 11 53 25 11 40 23 13 10 53 10 23 35 46 0 0 10 16 53 19 28 15 58 198 -55 10 23 23 10 10 24 11 40 34 8 53 51 45 0 0 8 46 54 19 28 32 60 197 -55 8 53 23 8 40 27 10 10 15 7 24 12 44 0 0 7 17 6 19 28 50 61 196 -56 7 23 33 7 10 40 8 40 4 5 54 46 43 0 0 5 47 36 19 29 9 63 195 -56 5 54 1 5 41 12 7 10 8 4 25 40 42 0 0 4 18 32 19 29 27 65 194 -56 4 24 54 4 12 10 5 40 36 2 57 2 41 0 0 2 50 0 19 29 46 66 193 -56 2 56 20 2 43 40 4 11 35 1 28 59 40 0 0 1 22 8 19 30 5 68 191 -57 1 28 26 1 15 51 2 43 11 0 1 38 39 0 0 - 0 4 58 19 30 24 69 190 -56 0 1 17 - 0 11 13 1 15 32 - 1 24 56 38 0 0 - 1 31 11 19 30 43 71 188 -56 - 1 24 59 - 1 37 23 - 0 11 16 - 2 50 36 37 0 0 - 2 56 27 19 31 2 72 185 -56 - 2 50 17 - 3 2 36 - 1 37 8 - 4 15 16 36 0 0 - 4 20 39 19 31 21 74 183 -56 - 4 14 32 - 4 26 45 - 3 1 57 - 5 38 52 35 0 0 - 5 43 43 19 31 40 75 180 -56 - 5 37 39 - 5 49 46 - 4 25 40 - 7 1 19 34 0 0 - 7 5 34 19 31 59 77 176 -55 - 6 59 33 - 7 11 35 - 5 48 11 - 8 22 31 33 0 0 - 8 26 9 19 32 17 78 171 -55 - 8 20 11 - 8 32 6 - 7 9 26 - 9 42 27 32 0 0 - 9 45 23 19 32 36 79 166 -54 - 9 39 28 - 9 51 17 - 8 29 21 -11 1 1 31 0 0 -11 3 14 19 32 54 80 159 -54 -10 57 22 -11 9 5 - 9 47 53 -12 18 11 30 0 0 -12 19 38 19 33 13 81 152 -53 -12 13 50 -12 25 26 -11 5 0 -13 33 54 29 0 0 -13 34 34 19 33 31 81 143 -52 -13 28 50 -13 40 19 -12 20 39 -14 48 9 28 0 0 -14 48 0 19 33 49 81 133 -51 -14 42 18 -14 53 41 -13 34 47 -16 0 52 27 0 0 -15 59 53 19 34 6 81 123 -51 -15 54 15 -16 5 31 -14 47 23 -17 12 4 26 0 0 -17 10 13 19 34 23 81 114 -50 -17 4 38 -17 15 47 -15 58 26 -18 21 41 25 0 0 -18 18 58 19 34 40 81 106 -49 -18 13 27 -18 24 29 -17 7 54 -19 29 44 24 0 0 -19 26 8 19 34 57 80 98 -48 -19 20 40 -19 31 36 -18 15 47 -20 36 12 23 0 0 -20 31 43 19 35 13 79 92 -48 -20 26 18 -20 37 8 -19 22 5 -21 41 5 22 0 0 -21 35 42 19 35 29 78 87 -47 -21 30 21 -21 41 4 -20 26 47 -22 44 22 21 0 0 -22 38 6 19 35 45 78 83 -46 -22 32 48 -22 43 24 -21 29 53 -23 46 4 20 0 0 -23 38 54 19 36 0 77 79 -45 -23 33 39 -23 44 9 -22 31 23 -24 46 11 19 0 0 -24 38 8 19 36 15 75 76 -44 -24 32 56 -24 43 20 -23 31 19 -25 44 44 18 0 0 -25 35 48 19 36 30 74 74 -43 -25 30 39 -25 40 56 -24 29 40 -26 41 43 17 0 0 -26 31 55 19 36 44 73 72 -42 -26 26 49 -26 37 0 -25 26 27 -27 37 9 16 0 0 -27 26 29 19 36 59 72 71 -41 -27 21 27 -27 31 32 -26 21 42 -28 31 4 15 0 0 -28 19 33 19 37 12 71 70 -41 -28 14 34 -28 24 32 -27 15 25 -29 23 29 14 0 0 -29 11 7 19 37 26 70 69 -40 -29 6 11 -29 16 3 -28 7 38 -30 14 24 13 0 0 -30 1 13 19 37 39 69 68 -39 -29 56 19 -30 6 6 -28 58 22 -31 3 51 12 0 0 -30 49 51 19 37 51 68 67 -38 -30 45 1 -30 54 41 -29 47 39 -31 51 53 11 0 0 -31 37 4 19 38 4 67 67 -37 -31 32 17 -31 41 52 -30 35 29 -32 38 29 10 0 0 -32 22 53 19 38 16 66 66 -36 -32 18 9 -32 27 38 -31 21 55 -33 23 42 9 0 0 -33 7 20 19 38 28 65 66 -35 -33 2 38 -33 12 2 -32 6 57 -34 7 33 8 0 0 -33 50 26 19 38 39 64 66 -35 -33 45 47 -33 55 5 -32 50 38 -34 50 4 7 0 0 -34 32 12 19 38 50 63 66 -34 -34 27 36 -34 36 49 -33 32 59 -35 31 16 6 0 0 -35 12 41 19 39 1 62 66 -33 -35 8 7 -35 17 15 -34 14 2 -36 11 11 5 0 0 -35 51 54 19 39 12 61 66 -32 -35 47 23 -35 56 25 -34 53 48 -36 49 52 4 0 0 -36 29 53 19 39 22 60 66 -31 -36 25 24 -36 34 21 -35 32 18 -37 27 18 3 0 0 -37 6 39 19 39 32 59 66 -31 -37 2 13 -37 11 5 -36 9 36 -38 3 33 2 0 0 -37 42 14 19 39 42 58 66 -30 -37 37 50 -37 46 38 -36 45 41 -38 38 38 1 0 0 -38 16 39 19 39 51 57 67 -29 -38 12 18 -38 21 1 -37 20 37 -39 12 33 0 0 0 -38 49 57 19 40 1 56 67 -28 -38 45 38 -38 54 16 -37 54 24 -39 45 22 - 1 0 0 -39 22 8 19 40 10 55 67 -27 -39 17 51 -39 26 25 -38 27 3 -40 17 5 - 2 0 0 -39 53 15 19 40 19 54 68 -27 -39 49 0 -39 57 30 -38 58 38 -40 47 44 - 3 0 0 -40 23 18 19 40 27 53 68 -26 -40 19 5 -40 27 31 -39 29 8 -41 17 21 - 4 0 0 -40 52 19 19 40 35 53 68 -25 -40 48 9 -40 56 30 -39 58 35 -41 45 56 - 5 0 0 -41 20 20 19 40 44 52 69 -25 -41 16 12 -41 24 29 -40 27 2 -42 13 32 - 6 0 0 -41 47 23 19 40 51 51 69 -24 -41 43 16 -41 51 29 -40 54 28 -42 40 10 - 7 0 0 -42 13 27 19 40 59 50 70 -23 -42 9 22 -42 17 32 -41 20 57 -43 5 50 - 8 0 0 -42 38 35 19 41 7 49 70 -22 -42 34 32 -42 42 38 -41 46 28 -43 30 35 - 9 0 0 -43 2 48 19 41 14 48 71 -22 -42 58 47 -43 6 50 -42 11 4 -43 54 26 - 10 0 0 -43 26 8 19 41 21 48 71 -21 -43 22 8 -43 30 7 -42 34 45 -44 17 24 - 11 0 0 -43 48 34 19 41 28 47 72 -20 -43 44 36 -43 52 32 -42 57 32 -44 39 30 - 12 0 0 -44 10 10 19 41 35 46 72 -20 -44 6 13 -44 14 6 -43 19 28 -45 0 45 - 13 0 0 -44 30 55 19 41 42 45 73 -19 -44 26 59 -44 34 50 -43 40 32 -45 21 10 - 14 0 0 -44 50 50 19 41 48 45 73 -18 -44 46 57 -44 54 44 -44 0 47 -45 40 47 - 15 0 0 -45 9 58 19 41 54 44 74 -18 -45 6 6 -45 13 50 -44 20 13 -45 59 37 - 16 0 0 -45 28 18 19 42 1 43 74 -17 -45 24 27 -45 32 9 -44 38 51 -46 17 40 - 17 0 0 -45 45 52 19 42 7 42 75 -16 -45 42 3 -45 49 42 -44 56 42 -46 34 57 - 18 0 0 -46 2 41 19 42 12 42 76 -16 -45 58 53 -46 6 29 -45 13 47 -46 51 30 - 19 0 0 -46 18 46 19 42 18 41 76 -15 -46 14 58 -46 22 33 -45 30 6 -47 7 19 - 20 0 0 -46 34 6 19 42 24 40 77 -14 -46 30 20 -46 37 52 -45 45 42 -47 22 24 - 21 0 0 -46 48 44 19 42 29 40 78 -14 -46 44 59 -46 52 29 -46 0 34 -47 36 48 - 22 0 0 -47 2 40 19 42 34 39 78 -13 -46 58 56 -47 6 24 -46 14 43 -47 50 31 - 23 0 0 -47 15 54 19 42 40 38 79 -13 -47 12 12 -47 19 37 -46 28 11 -48 3 32 - 24 0 0 -47 28 28 19 42 45 37 79 -12 -47 24 46 -47 32 10 -46 40 57 -48 15 54 - 25 0 0 -47 40 22 19 42 50 37 80 -11 -47 36 41 -47 44 3 -46 53 2 -48 27 36 - 26 0 0 -47 51 37 19 42 55 36 81 -11 -47 47 57 -47 55 17 -47 4 28 -48 38 40 - 27 0 0 -48 2 12 19 42 59 35 81 -10 -47 58 33 -48 5 51 -47 15 14 -48 49 5 - 28 0 0 -48 12 10 19 43 4 35 82 -10 -48 8 31 -48 15 48 -47 25 21 -48 58 52 - 29 0 0 -48 21 29 19 43 8 34 83 -9 -48 17 51 -48 25 7 -47 34 50 -49 8 3 - 30 0 0 -48 30 12 19 43 13 33 84 -8 -48 26 34 -48 33 49 -47 43 41 -49 16 37 - 31 0 0 -48 38 17 19 43 17 33 84 -8 -48 34 41 -48 41 54 -47 51 54 -49 24 34 - 32 0 0 -48 45 46 19 43 21 32 85 -7 -48 42 10 -48 49 22 -47 59 31 -49 31 56 - 33 0 0 -48 52 39 19 43 25 31 86 -7 -48 49 4 -48 56 14 -48 6 31 -49 38 42 - 34 0 0 -48 58 56 19 43 30 31 86 -6 -48 55 21 -49 2 31 -48 12 54 -49 44 53 - 35 0 0 -49 4 38 19 43 33 30 87 -5 -49 1 4 -49 8 13 -48 18 41 -49 50 29 - 36 0 0 -49 9 45 19 43 37 29 88 -5 -49 6 11 -49 13 19 -48 23 53 -49 55 31 - 37 0 0 -49 14 17 19 43 41 29 88 -4 -49 10 43 -49 17 50 -48 28 29 -49 59 58 - 38 0 0 -49 18 14 19 43 45 28 89 -4 -49 14 40 -49 21 47 -48 32 30 -50 3 52 - 39 0 0 -49 21 36 19 43 48 28 90 -3 -49 18 3 -49 25 10 -48 35 56 -50 7 11 - 40 0 0 -49 24 25 19 43 52 27 91 -2 -49 20 52 -49 27 58 -48 38 47 -50 9 57 - 41 0 0 -49 26 39 19 43 55 26 91 -2 -49 23 6 -49 30 12 -48 41 4 -50 12 9 - 42 0 0 -49 28 19 19 43 59 26 92 -1 -49 24 46 -49 31 52 -48 42 45 -50 13 47 - 43 0 0 -49 29 25 19 44 2 25 93 -1 -49 25 52 -49 32 57 -48 43 52 -50 14 52 - 44 0 0 -49 29 57 19 44 5 24 93 0 -49 26 24 -49 33 29 -48 44 24 -50 15 23 Uncertainty in time = +/- 9 secs Prediction of 2012 Jul 21.0 Data for the target star ------------------------ * name: HIP 93118 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 58 10.7699 DE: -20 25 25.609 * position source: mpos:HIP2 pm:HIP2 plx:HIP2 * standard error: RA,DE ["]: ( .009, .006 ) * V mag [mag]: 6.9 * B mag [mag]: 6.8 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (11889) 1991 AH2 approx. diameter [km]: 13 approx. diameter ["]: .013 distance from Earth [AU]: 1.42700 * orbital information: orbit source: Preston date of fit: 2012 Jul 21 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 739 number of rejected observations: 1 time covered by the observations: 1991 Jan 07 - 2012 Jul 17 1 sigma uncertainty ellipse (major, minor, PA): 0.080, 0.051, 104° remarks: * orbital elements for (11889) 1991 AH2 : Mean anomaly = 332.81565901 deg Arg. of pericenter = 214.33299954 deg Long. of node = 120.89536110 deg Inclination = 19.10498619 deg Eccentricity = 0.17756904 Semimajor axis = 2.76240171 AU Perihelion dist = 2.27188469 AU Mag: H = 12.05, G = 0.15 Epoch of elements : MJD 56146.81500000 TDT (2012 Aug 07.815) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 7 11889 1991 AH2 19h 34.0m UT 6.9 18 58 10.770-20 25 25.61HIP 93118 6.8 15.5 13 1.3 1.427 -1.332 -27.03 34.3219 -20.416 -112.08 16.13 19.5665 -0.11973 0.08381 -3.04157 -4.38766 0.00282 0.00009 2000 331.3526752012 8 1.00000214.333000120.895361 19.1049860.17756904 2.7624017 2.271884712.1 5.00.15 RATE 2.1467120 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.081 0.051 104 6.92 0.074 0 0-1 1 456129.0020120807__93118 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 21, 14:15 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org