IOTA/IOTA-ES occultation update for (87) Sylvia / 2UCAC 39809371 event on 2012 Aug 26, 17:28 UT Visible from Japan, E Russia, China Summary ------- On 2012 Aug 26 UT, the 263 km diameter asteroid (87) Sylvia will occult a 12.7 mag star in the constellation Taurus for observers along a path across Japan, E Russia, China. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.2 mag to 13.4 mag (the magnitude of the asteroid) for at most 10.2 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: 99 * date and approx. time of event: 2012 Aug 26, 17:25 - 2012 Aug 26, 17:27 UT * geocentric midpoint of event [JD]: 2456166.22810417 * magnitude of target star: 12.7 * magnitude drop [mag]: 1.2 * estimated maximum duration [s]: 10.2 * Moon: 73 % sunlit, 174° distance * Sun: 68° distance * rough path description: Japan, E Russia, China The occultation path -------------------- * approximate projected width [km]: 340 * 1 sigma uncertainty interval [path widths]: +/- 0.24 * 1 sigma uncertainty interval [seconds]: +/- 3.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .038 +/- .023) * 1 sigma uncertainty ellipse (major, minor, PA): ( .038", .023", 89° ) * approx speed of asteroid's shadow [km/s]: 25.6896 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 39809371 by 87 Sylvia on 2012 Aug 26 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 106 0 0 28 54 7 17 25 17 0 64 -51 .. .. .. 30 39 10 .. .. .. 31 30 42 107 0 0 29 20 31 17 25 17 1 64 -50 27 38 3 31 5 51 26 49 49 31 57 33 108 0 0 29 47 9 17 25 17 2 65 -49 28 4 25 31 32 49 27 16 3 32 24 40 109 0 0 30 14 3 17 25 17 3 65 -49 28 31 2 32 0 1 27 42 32 32 52 2 110 0 0 30 41 10 17 25 18 4 66 -48 28 57 52 32 27 26 28 9 15 33 19 36 111 0 0 31 8 31 17 25 18 5 66 -47 29 24 57 32 55 5 28 36 12 33 47 24 112 0 0 31 36 4 17 25 19 6 67 -47 29 52 14 33 22 55 29 3 21 34 15 24 113 0 0 32 3 49 17 25 19 7 67 -46 30 19 42 33 50 57 29 30 43 34 43 34 114 0 0 32 31 44 17 25 20 8 68 -45 30 47 22 34 19 9 29 58 15 35 11 55 115 0 0 32 59 49 17 25 21 9 68 -44 31 15 11 34 47 31 30 25 58 35 40 25 116 0 0 33 28 2 17 25 22 10 69 -44 31 43 10 35 16 1 30 53 50 36 9 3 117 0 0 33 56 24 17 25 23 11 70 -43 32 11 18 35 44 38 31 21 51 36 37 49 118 0 0 34 24 53 17 25 24 12 70 -42 32 39 33 36 13 22 31 50 0 37 6 41 119 0 0 34 53 28 17 25 25 13 71 -41 33 7 54 36 42 12 32 18 15 37 35 38 120 0 0 35 22 8 17 25 26 14 71 -41 33 36 21 37 11 6 32 46 36 38 4 40 121 0 0 35 50 52 17 25 27 15 72 -40 34 4 53 37 40 4 33 15 2 38 33 45 122 0 0 36 19 40 17 25 29 15 73 -39 34 33 29 38 9 5 33 43 33 39 2 52 123 0 0 36 48 30 17 25 30 16 73 -38 35 2 7 38 38 7 34 12 6 39 32 1 124 0 0 37 17 22 17 25 32 17 74 -37 35 30 48 39 7 11 34 40 42 40 1 10 125 0 0 37 46 14 17 25 33 18 75 -36 35 59 30 39 36 14 35 9 19 40 30 19 126 0 0 38 15 5 17 25 35 19 75 -36 36 28 12 40 5 16 35 37 57 40 59 27 127 0 0 38 43 55 17 25 37 20 76 -35 36 56 53 40 34 16 36 6 34 41 28 31 128 0 0 39 12 43 17 25 38 21 77 -34 37 25 33 41 3 12 36 35 10 41 57 33 129 0 0 39 41 27 17 25 40 22 78 -33 37 54 9 41 32 5 37 3 43 42 26 29 130 0 0 40 10 8 17 25 42 23 78 -32 38 22 43 42 0 53 37 32 14 42 55 21 131 0 0 40 38 43 17 25 44 23 79 -31 38 51 12 42 29 34 38 0 40 43 24 6 132 0 0 41 7 12 17 25 46 24 80 -31 39 19 36 42 58 9 38 29 1 43 52 44 133 0 0 41 35 34 17 25 48 25 81 -30 39 47 54 43 26 36 38 57 17 44 21 13 134 0 0 42 3 49 17 25 51 26 82 -29 40 16 4 43 54 55 39 25 26 44 49 34 135 0 0 42 31 54 17 25 53 27 82 -28 40 44 7 44 23 4 39 53 28 45 17 45 136 0 0 42 59 51 17 25 55 27 83 -27 41 12 1 44 51 2 40 21 21 45 45 44 137 0 0 43 27 37 17 25 57 28 84 -26 41 39 46 45 18 50 40 49 5 46 13 33 138 0 0 43 55 12 17 26 0 29 85 -25 42 7 20 45 46 25 41 16 39 46 41 8 139 0 0 44 22 35 17 26 2 30 86 -25 42 34 44 46 13 48 41 44 2 47 8 31 140 0 0 44 49 45 17 26 4 31 87 -24 43 1 55 46 40 57 42 11 14 47 35 40 141 0 0 45 16 42 17 26 7 31 88 -23 43 28 54 47 7 52 42 38 14 48 2 34 142 0 0 45 43 25 17 26 9 32 89 -22 43 55 40 47 34 32 43 5 1 48 29 12 143 0 0 46 9 54 17 26 12 33 90 -21 44 22 12 48 0 57 43 31 35 48 55 35 144 0 0 46 36 7 17 26 14 33 91 -21 44 48 29 48 27 6 43 57 54 49 21 41 145 0 0 47 2 4 17 26 17 34 92 -20 45 14 32 48 52 57 44 23 58 49 47 30 146 0 0 47 27 45 17 26 19 35 93 -19 45 40 18 49 18 32 44 49 48 50 13 1 147 0 0 47 53 9 17 26 22 35 94 -18 46 5 48 49 43 48 45 15 21 50 38 14 148 0 0 48 18 15 17 26 25 36 95 -17 46 31 2 50 8 46 45 40 37 51 3 8 149 0 0 48 43 3 17 26 27 37 96 -17 46 55 58 50 33 26 46 5 37 51 27 42 150 0 0 49 7 32 17 26 30 37 97 -16 47 20 36 50 57 46 46 30 19 51 51 57 151 0 0 49 31 43 17 26 33 38 99 -15 47 44 56 51 21 46 46 54 43 52 15 52 152 0 0 49 55 34 17 26 35 38 100 -14 48 8 57 51 45 26 47 18 49 52 39 27 153 0 0 50 19 6 17 26 38 39 101 -14 48 32 39 52 8 46 47 42 36 53 2 41 154 0 0 50 42 17 17 26 41 40 102 -13 48 56 2 52 31 45 48 6 4 53 25 33 155 0 0 51 5 8 17 26 43 40 103 -12 49 19 5 52 54 23 48 29 13 53 48 5 156 0 0 51 27 39 17 26 46 41 105 -11 49 41 48 53 16 40 48 52 1 54 10 15 157 0 0 51 49 48 17 26 49 41 106 -11 50 4 11 53 38 35 49 14 30 54 32 3 158 0 0 52 11 37 17 26 51 42 107 -10 50 26 13 54 0 9 49 36 38 54 53 29 159 0 0 52 33 4 17 26 54 42 108 -9 50 47 54 54 21 21 49 58 25 55 14 33 160 0 0 52 54 10 17 26 57 43 110 -8 51 9 14 54 42 11 50 19 52 55 35 15 161 0 0 53 14 54 17 26 59 43 111 -8 51 30 13 55 2 38 50 40 58 55 55 34 162 0 0 53 35 16 17 27 2 43 112 -7 51 50 51 55 22 44 51 1 43 56 15 31 163 0 0 53 55 16 17 27 5 44 114 -6 52 11 7 55 42 27 51 22 6 56 35 6 164 0 0 54 14 55 17 27 7 44 115 -6 52 31 2 56 1 48 51 42 8 56 54 18 165 0 0 54 34 12 17 27 10 45 116 -5 52 50 35 56 20 47 52 1 48 57 13 7 166 0 0 54 53 6 17 27 13 45 118 -4 53 9 46 56 39 24 52 21 7 57 31 34 167 0 0 55 11 39 17 27 15 45 119 -4 53 28 35 56 57 38 52 40 4 57 49 39 168 0 0 55 29 49 17 27 18 46 120 -3 53 47 3 57 15 30 52 58 40 58 7 22 169 0 0 55 47 38 17 27 20 46 122 -2 54 5 9 57 32 59 53 16 54 58 24 42 170 0 0 56 5 4 17 27 23 46 123 -2 54 22 53 57 50 7 53 34 46 58 41 39 171 0 0 56 22 9 17 27 26 47 125 -1 54 40 16 58 6 53 53 52 16 58 58 15 172 0 0 56 38 52 17 27 28 47 126 -1 54 57 17 58 23 16 54 9 25 59 14 29 Uncertainty in time = +/- 4 secs Prediction of 2012 Jul 8.0 Data for the target star ------------------------ * name: 2UCAC 39809371 * constellation : Taurus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 05 42 41.9747 DE: +22 53 36.372 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .037, .023 ) * V mag [mag]: 12.7 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (87) Sylvia approx. diameter [km]: 263 approx. diameter ["]: .097 distance from Earth [AU]: 3.73600 * orbital information: orbit source: Preston date of fit: 2012 Jul 08 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 2200 number of rejected observations: 103 time covered by the observations: 1909 Apr 21 - 2012 Feb 02 1 sigma uncertainty ellipse (major, minor, PA): 0.009, 0.006, 76° remarks: * orbital elements for (87) Sylvia : Mean anomaly = 81.36496284 deg Arg. of pericenter = 265.91488185 deg Long. of node = 73.14304646 deg Inclination = 10.88500793 deg Eccentricity = 0.08693952 Semimajor axis = 3.49875815 AU Perihelion dist = 3.19457779 AU Mag: H = 6.70, G = 0.15 Epoch of elements : MJD 56165.72800000 TDT (2012 Aug 26.728) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 26 87 Sylvia 17h 28.5m UT 12.7 5 42 41.975 22 53 36.372UCAC 39809371 0.0 13.4 263 10.2 3.736 2.446 4.75 -151.8081 22.893 -81.71 10.09 17.4745 -0.08946 0.62774 14.35862 2.01933 -0.00532 -0.00018 2000 80.5023102012 821.00000265.914882 73.143046 10.8850080.08693952 3.4987582 3.1945778 6.9 5.00.15 RATE 1.5060280 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.038 0.023 89 1.24 0.024 2 7 706 18 1356 0-3 2 056116.0020120826_809371 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 08, 00:02 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org