IOTA/IOTA-ES occultation update for (385) Ilmatar / TYC 1795-00455-1 event on 2012 Aug 24, 18:41 UT Visible from E Russia, China, SE Asia Summary ------- On 2012 Aug 24 UT, the 84 km diameter asteroid (385) Ilmatar will occult a 8.5 mag star in the constellation Aries for observers along a path across E Russia, China, SE Asia. In the case of an occultation, the combined light of the asteroid and the star will drop by 4.6 mag to 13.1 mag (the magnitude of the asteroid) for at most 6.3 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: UCAC. The event at a glimpse ---------------------- * Rank: 92 * date and approx. time of event: 2012 Aug 24, 18:35 - 2012 Aug 24, 18:45 UT * geocentric midpoint of event [JD]: 2456164.27902083 * magnitude of target star: 8.5 * magnitude drop [mag]: 4.6 * estimated maximum duration [s]: 6.3 * Moon: 52 % sunlit, 164° distance * Sun: 98° distance * rough path description: E Russia, China, SE Asia The occultation path -------------------- * approximate projected width [km]: 99 * 1 sigma uncertainty interval [path widths]: +/- 0.50 * 1 sigma uncertainty interval [seconds]: +/- 3.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .021 +/- .021) * 1 sigma uncertainty ellipse (major, minor, PA): ( .021", .021", 80° ) * approx speed of asteroid's shadow [km/s]: 13.3114 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 1795-00455-1 by 385 Ilmatar on 2012 Aug 24 Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 E. Longitude Latitude U.T. Alt Az Alt o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' " Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude 81 29 38 -10 18 1 18 35 6 8 58 -89 79 55 58 -10 53 42 82 48 17 - 9 51 12 77 50 7 -11 48 19 83 57 44 - 9 29 52 85 50 39 - 6 42 12 18 35 16 14 57 -84 84 54 30 - 6 55 39 86 43 37 - 6 30 41 83 54 23 - 7 11 30 87 33 54 - 6 20 48 88 41 40 - 4 0 54 18 35 27 17 57 -80 87 55 34 - 4 8 16 89 26 7 - 3 54 34 87 7 37 - 4 16 46 90 9 6 - 3 49 9 90 55 19 - 1 42 50 18 35 37 21 57 -77 90 14 17 - 1 47 3 91 35 17 - 1 39 17 89 32 3 - 1 52 2 92 14 15 - 1 36 23 92 47 13 0 21 25 18 35 47 23 57 -74 92 9 16 0 19 10 93 24 21 0 23 10 91 30 27 0 16 21 94 0 45 0 24 24 94 24 29 2 16 12 18 35 57 26 58 -72 93 48 38 2 15 20 94 59 42 2 16 39 93 12 6 2 14 1 95 34 18 2 16 42 95 51 8 4 3 59 18 36 8 28 58 -69 95 16 48 4 4 8 96 24 56 4 3 27 94 41 53 4 3 56 96 58 13 4 2 35 97 9 38 5 46 17 18 36 18 30 59 -67 96 36 25 5 47 16 97 42 22 5 45 0 96 2 44 5 47 56 98 14 40 5 43 23 98 21 40 7 24 13 18 36 28 32 59 -65 97 49 20 7 25 52 98 53 35 7 22 17 97 16 33 7 27 13 99 25 7 7 20 5 99 28 26 8 58 30 18 36 39 34 60 -63 98 56 46 9 0 42 99 59 43 8 56 2 98 24 42 9 2 38 100 30 38 8 53 19 100 30 47 10 29 43 18 36 49 35 61 -61 99 59 39 10 32 24 101 1 35 10 26 48 99 28 10 10 34 50 101 32 1 10 23 39 101 29 26 11 58 19 18 36 59 37 61 -60 100 58 43 12 1 25 101 59 50 11 55 0 100 27 40 12 4 16 102 29 54 11 51 28 102 24 54 13 24 39 18 37 10 38 62 -58 101 54 30 13 28 7 102 54 59 13 20 59 101 23 47 13 31 21 103 24 46 13 17 7 103 17 35 14 49 0 18 37 20 40 63 -56 102 47 27 14 52 47 103 47 26 14 45 2 102 17 0 14 56 22 104 17 0 14 40 51 104 7 52 16 11 37 18 37 30 41 64 -55 103 37 54 16 15 41 104 37 33 16 7 21 103 7 39 16 19 34 105 6 57 16 2 53 104 56 1 17 32 40 18 37 40 42 65 -53 104 26 11 17 37 1 105 25 34 17 28 9 103 56 4 17 41 11 105 54 52 17 23 26 105 42 16 18 52 21 18 37 51 44 66 -52 105 12 31 18 56 57 106 11 45 18 47 35 104 42 30 19 1 22 106 40 59 18 42 38 106 26 51 20 10 48 18 38 1 45 67 -50 105 57 8 20 15 38 106 56 18 20 5 48 105 27 10 20 20 17 107 25 30 20 0 38 107 9 55 21 28 9 18 38 11 46 69 -49 106 40 13 21 33 12 107 39 23 21 22 56 106 10 14 21 38 4 108 8 35 21 17 34 107 51 39 22 44 30 18 38 22 47 70 -47 107 21 54 22 49 45 108 21 9 22 39 5 106 51 54 22 54 51 108 50 23 22 33 31 108 32 10 23 59 58 18 38 32 48 71 -46 108 2 21 24 5 25 109 1 44 23 54 22 107 32 17 24 10 42 109 31 3 23 48 36 109 11 35 25 14 38 18 38 42 49 73 -45 108 41 40 25 20 16 109 41 15 25 8 50 108 11 31 25 25 44 110 10 40 25 2 53 109 50 1 26 28 34 18 38 52 50 74 -43 109 19 59 26 34 23 110 19 49 26 22 36 108 49 42 26 40 2 110 49 22 26 16 28 110 27 34 27 41 51 18 39 3 51 76 -42 109 57 23 27 47 51 110 57 31 27 35 42 109 26 56 27 53 41 111 27 13 27 29 25 111 4 19 28 54 34 18 39 13 52 77 -41 110 33 56 29 0 43 111 34 27 28 48 15 110 3 19 29 6 44 112 4 20 28 41 47 111 40 21 30 6 45 18 39 23 53 79 -40 111 9 45 30 13 4 112 10 41 30 0 16 110 38 55 30 19 15 112 40 47 29 53 39 112 15 44 31 18 28 18 39 34 53 81 -38 111 44 54 31 24 58 112 46 18 31 11 50 111 13 49 31 31 18 113 16 37 31 5 3 112 50 32 32 29 47 18 39 44 54 83 -37 112 19 27 32 36 27 113 21 22 32 23 0 111 48 5 32 42 57 113 51 57 32 16 3 113 24 49 33 40 45 18 39 54 55 84 -36 112 53 26 33 47 34 113 55 57 33 33 48 112 21 48 33 54 14 114 26 48 33 26 42 113 58 40 34 51 24 18 40 4 55 86 -35 113 26 58 34 58 23 114 30 6 34 44 17 112 54 59 35 5 12 115 1 16 34 37 2 114 32 6 36 1 48 18 40 15 56 88 -33 114 0 3 36 8 56 115 3 53 35 54 31 113 27 44 36 15 54 115 35 23 35 47 6 115 5 12 37 11 58 18 40 25 56 90 -32 114 32 47 37 19 15 115 37 21 37 4 32 114 0 5 37 26 24 116 9 14 36 56 58 115 38 2 38 21 58 18 40 35 57 93 -31 115 5 12 38 29 25 116 10 34 38 14 22 114 32 5 38 36 43 116 42 50 38 6 38 116 10 37 39 31 49 18 40 46 57 95 -30 115 37 21 39 39 26 116 43 35 39 24 4 115 3 47 39 46 53 117 16 16 39 16 10 116 43 1 40 41 35 18 40 56 57 97 -29 116 9 17 40 49 21 117 16 27 40 33 39 115 35 14 40 56 58 117 49 36 40 25 36 117 15 18 41 51 17 18 41 6 58 99 -27 116 41 3 41 59 13 117 49 14 41 43 11 116 6 29 42 7 0 118 22 51 41 34 58 117 47 30 43 0 57 18 41 17 58 102 -26 117 12 42 43 9 4 118 21 58 42 52 42 116 37 35 43 17 1 118 56 6 42 44 18 118 19 40 44 10 39 18 41 27 58 104 -25 117 44 17 44 18 56 118 54 42 44 2 14 117 8 34 44 27 4 119 29 24 43 53 39 118 51 52 45 20 25 18 41 37 58 106 -24 118 15 52 45 28 52 119 27 31 45 11 48 117 39 31 45 37 10 120 2 49 45 3 3 119 24 10 46 30 15 18 41 47 58 109 -23 118 47 29 46 38 53 120 0 28 46 21 28 118 10 27 46 47 22 120 36 25 46 12 32 119 56 36 47 40 14 18 41 58 58 111 -22 119 19 13 47 49 3 120 33 37 47 31 15 118 41 25 47 57 43 121 10 14 47 22 8 120 29 15 48 50 23 18 42 8 58 114 -21 119 51 5 48 59 24 121 7 1 48 41 13 119 12 30 49 8 15 121 44 23 48 31 53 121 2 11 50 0 44 18 42 18 58 116 -20 120 23 11 50 9 57 121 40 45 49 51 22 119 43 44 50 19 0 122 18 54 49 41 50 121 35 27 51 11 20 18 42 29 58 119 -18 120 55 33 51 20 45 122 14 54 51 1 45 120 15 12 51 30 0 122 53 54 50 52 1 122 9 9 52 22 13 18 42 39 57 121 -17 121 28 18 52 31 51 122 49 32 52 12 26 120 46 57 52 41 19 123 29 27 52 2 28 122 43 23 53 33 27 18 42 49 57 123 -16 122 1 28 53 43 18 123 24 46 53 23 25 121 19 3 53 52 59 124 5 40 53 13 14 123 18 13 54 45 2 18 42 59 57 126 -15 122 35 11 54 55 8 124 0 42 54 34 47 121 51 36 55 5 2 124 42 39 54 24 21 123 53 47 55 57 3 18 43 10 56 128 -14 123 9 32 56 7 23 124 37 27 55 46 32 122 24 40 56 17 32 125 20 32 55 35 52 124 30 12 57 9 32 18 43 20 56 130 -13 123 44 37 57 20 7 125 15 9 56 58 45 122 58 23 57 30 31 125 59 28 56 47 48 125 7 37 58 22 31 18 43 30 55 132 -12 124 20 35 58 33 23 125 53 57 58 11 28 123 32 51 58 44 3 126 39 37 58 0 14 125 46 11 59 36 5 18 43 41 55 135 -11 124 57 35 59 47 14 126 34 3 59 24 44 124 8 13 59 58 11 127 21 11 59 13 12 126 26 8 60 50 15 18 43 51 54 137 -10 125 35 47 61 1 43 127 15 39 60 38 36 124 44 37 61 12 58 128 4 23 60 26 45 127 7 40 62 5 7 18 44 1 53 139 -8 126 15 25 62 16 54 127 59 1 61 53 8 125 22 16 62 28 28 128 49 30 61 40 56 127 51 5 63 20 43 18 44 11 53 141 -7 126 56 44 63 32 51 128 44 27 63 8 22 126 1 22 63 44 46 129 36 51 62 55 49 128 36 44 64 37 7 18 44 22 52 143 -6 127 40 2 64 49 38 129 32 19 64 24 23 126 42 13 65 1 55 130 26 50 64 11 27 129 25 1 65 54 24 18 44 32 51 145 -5 128 25 43 66 7 19 130 23 5 65 41 15 127 25 9 66 20 0 131 19 56 65 27 53 130 16 29 67 12 38 18 44 42 50 147 -4 129 14 16 67 26 0 131 17 19 66 59 2 128 10 36 67 39 6 132 16 47 66 45 13 131 11 49 68 31 54 18 44 53 49 149 -3 130 6 17 68 45 44 132 15 45 68 17 48 128 59 6 68 59 19 133 18 7 68 3 29 132 11 52 69 52 17 18 45 3 48 152 -2 131 2 35 70 6 39 133 19 19 69 37 38 129 51 24 70 20 44 134 24 58 69 22 45 133 17 50 71 13 51 18 45 13 47 154 -1 132 4 15 71 28 49 134 29 16 70 58 37 130 48 26 71 43 29 135 38 36 70 43 7 Uncertainty in time = +/- 3 secs Prediction of 2012 Jul 21.0 Data for the target star ------------------------ * name: TYC 1795-00455-1 * constellation : Aries * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 03 12 15.8131 DE: +29 49 07.261 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .016, .019 ) * V mag [mag]: 8.5 * B mag [mag]: 9.2 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (385) Ilmatar approx. diameter [km]: 84 approx. diameter ["]: .042 distance from Earth [AU]: 2.78400 * orbital information: orbit source: Preston date of fit: 2012 Jul 21 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 817 number of rejected observations: 116 time covered by the observations: 1904 May 06 - 2012 Jan 01 1 sigma uncertainty ellipse (major, minor, PA): 0.014, 0.010, 68° remarks: * orbital elements for (385) Ilmatar : Mean anomaly = 232.84879115 deg Arg. of pericenter = 187.56438264 deg Long. of node = 345.19469339 deg Inclination = 13.54914082 deg Eccentricity = 0.12417427 Semimajor axis = 2.85062322 AU Perihelion dist = 2.49664918 AU Mag: H = 7.48, G = 0.15 Epoch of elements : MJD 56163.77900000 TDT (2012 Aug 24.779) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 24 385 Ilmatar 18h 41.8m UT 8.5 3 12 15.813 29 49 7.26TYC 1795-00455-1 9.2 13.1 84 6.3 2.784 1.204 17.83 154.1737 29.814 -99.90 10.76 18.6965 -0.39519 0.34462 4.96135 5.64227 -0.00537 -0.00169 2000 232.0749152012 821.00000187.564383345.194693 13.5491410.12417427 2.8506232 2.4966492 7.5 5.00.15 RATE 2.0478320 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.021 0.021 80 1.50 0.021 0 0 1 1 456129.0020120824_0455-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 21, 14:45 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org