IOTA/IOTA-ES occultation update for (140) Siwa / TYC 6342-01234-1 event on 2009 Aug 09, 06:21 UT Visible from W USA, Canada Summary ------- On 2009 Aug 09 UT, the 110 km diameter asteroid (140) Siwa will occult a 11.2 mag star in the constellation Capricornus for observers along a path across W USA, Canada. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.5 mag to 10.7 mag (the magnitude of the asteroid) for at most 16.9 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: 2009 Aug 09, 06:13 - 2009 Aug 09, 06:30 UT * magnitude of target star: 11.2 * magnitude drop [mag]: 0.5 * estimated maximum duration [s]: 16.9 * Moon: 90 % sunlit, 47° distance * Sun: 169° distance * rough path description: W USA, Canada The occultation path -------------------- * approximate projected width [km]: 207 * 1 sigma uncertainty interval [path widths]: +/- 0.22 * 1 sigma uncertainty interval [seconds]: +/- 5.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .042 +/- .029) * 1 sigma uncertainty ellipse (major, minor, PA): ( .042", .029", 83° ) * approx speed of asteroid's shadow [km/s]: 6.4861 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6342-01234-1 by 140 Siwa on 2009 Aug 9 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 - 79 23 2 67 0 0 6 13 16 0 201 -7 - 82 2 10 ... .. .. - 83 13 2 ... .. .. - 80 24 8 66 0 0 6 13 16 1 201 -8 - 82 58 6 - 77 52 28 - 84 6 40 - 76 46 22 - 81 25 28 65 0 0 6 13 17 2 200 -9 - 83 54 45 - 78 58 28 - 85 1 15 - 77 54 25 - 82 27 8 64 0 0 6 13 19 4 199 -10 - 84 52 10 - 80 4 21 - 85 56 48 - 79 2 10 - 83 29 12 63 0 0 6 13 21 5 198 -11 - 85 50 24 - 81 10 15 - 86 53 20 - 80 9 44 - 84 31 44 62 0 0 6 13 25 6 197 -12 - 86 49 28 - 82 16 16 - 87 50 52 - 81 17 17 - 85 34 51 61 0 0 6 13 28 7 196 -13 - 87 49 26 - 83 22 31 - 88 49 27 - 82 24 56 - 86 38 36 60 0 0 6 13 33 8 195 -14 - 88 50 20 - 84 29 7 - 89 49 6 - 83 32 48 - 87 43 4 59 0 0 6 13 39 9 194 -15 - 89 52 14 - 85 36 9 - 90 49 52 - 84 40 58 - 88 48 19 58 0 0 6 13 45 10 193 -16 - 90 55 11 - 86 43 44 - 91 51 49 - 85 49 34 - 89 54 25 57 0 0 6 13 52 11 192 -17 - 91 59 14 - 87 51 55 - 92 54 58 - 86 58 41 - 91 1 29 56 0 0 6 13 59 12 191 -18 - 93 4 28 - 89 0 50 - 93 59 24 - 88 8 26 - 92 9 34 55 0 0 6 14 8 13 190 -19 - 94 10 57 - 90 10 34 - 95 5 11 - 89 18 53 - 93 18 45 54 0 0 6 14 17 15 189 -20 - 95 18 44 - 91 21 12 - 96 12 22 - 90 30 10 - 94 29 8 53 0 0 6 14 27 16 188 -21 - 96 27 56 - 92 32 49 - 97 21 3 - 91 42 22 - 95 40 49 52 0 0 6 14 38 17 187 -22 - 97 38 37 - 93 45 33 - 98 31 19 - 92 55 34 - 96 53 53 51 0 0 6 14 50 18 186 -23 - 98 50 53 - 94 59 29 - 99 43 17 - 94 9 54 - 98 8 27 50 0 0 6 15 3 19 185 -24 -100 4 52 - 96 14 44 -100 57 1 - 95 25 28 - 99 24 39 49 0 0 6 15 16 20 183 -25 -101 20 40 - 97 31 25 -102 12 41 - 96 42 23 -100 42 36 48 0 0 6 15 31 21 182 -26 -102 38 26 - 98 49 39 -103 30 25 - 98 0 47 -102 2 27 47 0 0 6 15 47 22 181 -27 -103 58 19 -100 9 35 -104 50 21 - 99 20 48 -103 24 21 46 0 0 6 16 3 23 180 -28 -105 20 29 -101 31 23 -106 12 40 -100 42 35 -104 48 30 45 0 0 6 16 21 24 178 -28 -106 45 7 -102 55 11 -107 37 36 -102 6 17 -106 15 5 44 0 0 6 16 40 25 177 -29 -108 12 28 -104 21 12 -109 5 22 -103 32 7 -107 44 21 43 0 0 6 16 59 26 175 -30 -109 42 48 -105 49 38 -110 36 14 -105 0 14 -109 16 33 42 0 0 6 17 20 27 174 -30 -111 16 23 -107 20 44 -112 10 32 -106 30 55 -110 52 1 41 0 0 6 17 43 28 172 -31 -112 53 37 -108 54 46 -113 48 40 -108 4 24 -112 31 7 40 0 0 6 18 6 28 171 -31 -114 34 54 -110 32 3 -115 31 4 -109 41 0 -114 14 16 39 0 0 6 18 31 29 169 -32 -116 20 46 -112 12 59 -117 18 18 -111 21 5 -116 2 2 38 0 0 6 18 57 30 167 -32 -118 11 52 -113 58 0 -119 11 6 -113 5 3 -117 55 3 37 0 0 6 19 26 31 165 -33 -120 9 0 -115 47 40 -121 10 20 -114 53 25 -119 54 10 36 0 0 6 19 55 31 163 -33 -122 13 12 -117 42 38 -123 17 11 -116 46 49 -122 0 25 35 0 0 6 20 27 31 160 -33 -124 25 52 -119 43 47 -125 33 12 -118 46 1 Latitude Latitude Latitude Latitude -124 0 0 34 6 35 6 20 57 32 158 -33 35 11 22 33 3 57 35 40 38 32 37 1 -125 0 0 33 41 1 6 21 12 32 157 -32 34 45 15 32 38 54 35 14 14 32 12 11 -126 0 0 33 16 17 6 21 28 32 156 -32 34 19 59 32 14 39 34 48 43 31 48 8 -127 0 0 32 52 23 6 21 43 32 155 -32 33 55 34 31 51 13 34 24 3 31 24 53 -128 0 0 32 29 18 6 21 58 32 154 -32 33 31 59 31 28 34 34 0 15 31 2 25 -129 0 0 32 7 3 6 22 13 32 153 -32 33 9 16 31 6 44 33 37 19 30 40 45 -130 0 0 31 45 36 6 22 28 32 152 -31 32 47 24 30 45 41 33 15 14 30 19 52 -131 0 0 31 24 59 6 22 43 32 151 -31 32 26 22 30 25 27 32 54 0 29 59 47 -132 0 0 31 5 11 6 22 57 32 150 -31 32 6 10 30 6 0 32 33 37 29 40 29 -133 0 0 30 46 12 6 23 12 32 149 -31 31 46 49 29 47 21 32 14 6 29 21 59 -134 0 0 30 28 2 6 23 27 31 148 -30 31 28 18 29 29 30 31 55 25 29 4 16 -135 0 0 30 10 41 6 23 41 31 147 -30 31 10 37 29 12 27 31 37 34 28 47 20 -136 0 0 29 54 8 6 23 56 31 146 -29 30 53 46 28 56 11 31 20 35 28 31 11 -137 0 0 29 38 24 6 24 10 31 145 -29 30 37 45 28 40 44 31 4 25 28 15 50 -138 0 0 29 23 29 6 24 24 30 144 -29 30 22 33 28 26 3 30 49 7 28 1 16 -139 0 0 29 9 23 6 24 38 30 143 -28 30 8 12 28 12 11 30 34 38 27 47 29 -140 0 0 28 56 5 6 24 52 30 142 -28 29 54 40 27 59 6 30 21 0 27 34 30 -141 0 0 28 43 36 6 25 6 30 141 -27 29 41 58 27 46 49 30 8 12 27 22 18 -142 0 0 28 31 56 6 25 19 29 140 -27 29 30 6 27 35 20 29 56 14 27 10 53 -143 0 0 28 21 4 6 25 32 29 140 -26 29 19 3 27 24 38 29 45 6 27 0 15 -144 0 0 28 11 1 6 25 45 28 139 -25 29 8 50 27 14 44 29 34 48 26 50 25 -145 0 0 28 1 47 6 25 58 28 138 -25 28 59 27 27 5 37 29 25 21 26 41 22 -146 0 0 27 53 21 6 26 11 27 137 -24 28 50 54 26 57 19 29 16 44 26 33 7 -147 0 0 27 45 44 6 26 24 27 136 -24 28 43 10 26 49 48 29 8 57 26 25 39 -148 0 0 27 38 56 6 26 36 26 136 -23 28 36 16 26 43 6 29 2 0 26 18 58 -149 0 0 27 32 57 6 26 48 26 135 -22 28 30 12 26 37 11 28 55 54 26 13 5 -150 0 0 27 27 47 6 27 0 25 134 -22 28 24 58 26 32 5 28 50 38 26 8 1 -151 0 0 27 23 26 6 27 12 25 133 -21 28 20 34 26 27 46 28 46 13 26 3 43 -152 0 0 27 19 54 6 27 23 24 133 -20 28 17 0 26 24 17 28 42 38 26 0 14 -153 0 0 27 17 12 6 27 34 24 132 -20 28 14 17 26 21 35 28 39 54 25 57 33 -154 0 0 27 15 19 6 27 45 23 131 -19 28 12 24 26 19 42 28 38 1 25 55 40 -155 0 0 27 14 15 6 27 56 22 130 -18 28 11 21 26 18 38 28 36 59 25 54 36 -156 0 0 27 14 2 6 28 6 22 130 -17 28 11 10 26 18 23 28 36 48 25 54 20 -157 0 0 27 14 38 6 28 16 21 129 -17 28 11 49 26 18 57 28 37 29 25 54 53 -158 0 0 27 16 5 6 28 26 20 129 -16 28 13 19 26 20 20 28 39 1 25 56 15 -159 0 0 27 18 22 6 28 36 20 128 -15 28 15 41 26 22 33 28 41 25 25 58 25 -160 0 0 27 21 30 6 28 45 19 127 -14 28 18 55 26 25 35 28 44 41 26 1 26 -161 0 0 27 25 28 6 28 54 18 127 -14 28 23 0 26 29 27 28 48 50 26 5 15 -162 0 0 27 30 18 6 29 2 18 126 -13 28 27 58 26 34 10 28 53 51 26 9 55 -163 0 0 27 35 59 6 29 10 17 126 -12 28 33 47 26 39 43 28 59 45 26 15 24 -164 0 0 27 42 32 6 29 18 16 125 -11 28 40 30 26 46 6 29 6 32 26 21 44 -165 0 0 27 49 56 6 29 26 15 124 -10 28 48 5 26 53 20 29 14 13 26 28 54 -166 0 0 27 58 13 6 29 33 14 124 -9 28 56 34 27 1 26 29 22 47 26 36 55 -167 0 0 28 7 22 6 29 40 14 123 -9 29 5 57 27 10 23 29 32 16 26 45 47 -168 0 0 28 17 24 6 29 46 13 123 -8 29 16 13 27 20 12 29 42 39 26 55 30 -169 0 0 28 28 20 6 29 52 12 122 -7 29 27 24 27 30 53 29 53 58 27 6 5 -170 0 0 28 40 9 6 29 58 11 122 -6 29 39 30 27 42 27 30 6 11 27 17 33 -171 0 0 28 52 52 6 30 4 10 121 -5 29 52 31 27 54 53 30 19 20 27 29 52 -172 0 0 29 6 29 6 30 8 10 121 -4 30 6 28 28 8 13 30 33 26 27 43 4 -173 0 0 29 21 1 6 30 13 9 120 -3 30 21 20 28 22 26 30 48 28 27 57 10 -174 0 0 29 36 28 6 30 17 8 120 -2 30 37 9 28 37 33 31 4 28 28 12 8 -175 0 0 29 52 51 6 30 21 7 119 -2 30 53 55 28 53 34 31 21 25 28 28 1 -176 0 0 30 10 10 6 30 24 6 119 -1 31 11 39 29 10 30 31 39 20 28 44 48 Uncertainty in time = +/- 5 secs Prediction of 2009 Aug 6.0 Data for the target star ------------------------ * name: TYC 6342-01234-1 * constellation : Capricornus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 20 34 35.5479 DE: -21 11 07.269 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .025, .025 ) * V mag [mag]: 11.2 * B mag [mag]: 12.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (140) Siwa approx. diameter [km]: 110 approx. diameter ["]: .133 distance from Earth [AU]: 1.13800 * orbital information: orbit source: Preston date of fit: 2009 Aug 06 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1319 number of rejected observations: 180 time covered by the observations: 1900 Apr 26 - 2009 Jul 07 1 sigma uncertainty ellipse (major, minor, PA): 0.034, 0.014, 79° remarks: * orbital elements for (140) Siwa : Mean anomaly = 3.97908403 deg Arg. of pericenter = 197.25124246 deg Long. of node = 107.29450918 deg Inclination = 3.18727781 deg Eccentricity = 0.21730031 Semimajor axis = 2.73306172 AU Perihelion dist = 2.13916657 AU Mag: H = 8.47, G = 0.15 Epoch of elements : MJD 55052.26500000 TDT (2009 Aug 09.265) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Aug 9 140 Siwa 6h 21.9m UT 11.2 20 34 35.548-21 11 7.27TYC 6342-01234-1 12.1 10.7 110 16.9 1.138 -1.861 -11.06 -104.7073 -21.181 85.91 15.80 6.3647 -0.33109 0.77954 -3.36940 -1.43168 0.00090 0.00045 2000 3.4850032009 8 7.00000197.251242107.294509 3.1872780.21730031 2.7330617 2.1391666 8.3 5.00.15 RATE 2.1813730 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.042 0.029 83 1.22 0.030 0 55049.0020090809_1234-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2009 Aug 06, 11:26 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org