IOTA/IOTA-ES occultation update for (140) Siwa / TYC 6341-00068-1 event on 2009 Oct 02, 04:12 UT Visible from S Canada, W USA Summary ------- On 2009 Oct 02 UT, the 110 km diameter asteroid (140) Siwa will occult a 11.1 mag star in the constellation Capricornus for observers along a path across S Canada, W USA. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.4 mag to 12.1 mag (the magnitude of the asteroid) for at most 13.3 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 98 * date and approx. time of event: 2009 Oct 02, 04:09 - 2009 Oct 02, 04:20 UT * magnitude of target star: 11.1 * magnitude drop [mag]: 1.4 * estimated maximum duration [s]: 13.3 * Moon: 95 % sunlit, 41° distance * Sun: 116° distance * rough path description: S Canada, W USA The occultation path -------------------- * approximate projected width [km]: 185 * 1 sigma uncertainty interval [path widths]: +/- 0.37 * 1 sigma uncertainty interval [seconds]: +/- 4.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .036) * 1 sigma uncertainty ellipse (major, minor, PA): ( .036", .032", 359° ) * approx speed of asteroid's shadow [km/s]: 8.2641 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6341-00068-1 by 140 Siwa on 2009 Oct 2 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 - 82 10 51 59 0 0 4 20 27 1 222 -34 - 80 1 7 - 84 21 18 ... .. .. - 85 58 26 - 83 57 6 58 0 0 4 20 27 2 220 -34 - 81 50 31 - 86 4 32 ... .. .. - 87 39 30 - 85 41 36 57 0 0 4 20 25 4 219 -35 - 83 37 50 - 87 46 19 ... .. .. - 89 19 21 - 87 24 38 56 0 0 4 20 23 5 217 -35 - 85 23 24 - 89 26 56 - 83 54 15 - 90 58 14 - 89 6 30 55 0 0 4 20 20 6 216 -36 - 87 7 31 - 91 6 39 - 85 40 6 - 92 36 26 - 90 47 27 54 0 0 4 20 16 8 215 -36 - 88 50 27 - 92 45 42 - 87 24 35 - 94 14 8 - 92 27 43 53 0 0 4 20 11 9 213 -37 - 90 32 29 - 94 24 19 - 89 7 58 - 95 51 36 - 94 7 33 52 0 0 4 20 6 10 212 -37 - 92 13 50 - 96 2 43 - 90 50 31 - 97 29 1 - 95 47 10 51 0 0 4 20 0 12 210 -37 - 93 54 45 - 97 41 8 - 92 32 27 - 99 6 36 - 97 26 47 50 0 0 4 19 52 13 209 -37 - 95 35 27 - 99 19 46 - 94 14 2 -100 44 36 - 99 6 37 49 0 0 4 19 44 15 208 -37 - 97 16 10 -100 58 51 - 95 55 27 -102 23 12 -100 46 54 48 0 0 4 19 35 16 206 -37 - 98 57 6 -102 38 36 - 97 36 57 -104 2 38 -102 27 51 47 0 0 4 19 25 18 205 -37 -100 38 30 -104 19 15 - 99 18 46 -105 43 10 -104 9 44 46 0 0 4 19 14 19 203 -37 -102 20 35 -106 1 4 -101 1 6 -107 25 1 -105 52 46 45 0 0 4 19 2 20 202 -37 -104 3 37 -107 44 17 -102 44 12 -109 8 31 -107 37 15 44 0 0 4 18 49 22 200 -36 -105 47 50 -109 29 14 -104 28 20 -110 53 56 -109 23 29 43 0 0 4 18 34 23 198 -36 -107 33 32 -111 16 13 -106 13 46 -112 41 39 -111 11 48 42 0 0 4 18 19 24 197 -35 -109 21 1 -113 5 38 -108 0 47 -114 32 4 -113 2 36 41 0 0 4 18 2 26 195 -34 -111 10 38 -114 57 53 -109 49 42 -116 25 38 -114 56 18 40 0 0 4 17 44 27 193 -34 -113 2 48 -116 53 30 -111 40 55 -118 22 56 -116 53 26 39 0 0 4 17 24 28 191 -33 -114 57 56 -118 53 3 -113 34 49 -120 24 38 -118 54 37 38 0 0 4 17 3 30 189 -32 -116 56 37 -120 57 19 -115 31 55 -122 31 36 Latitude Latitude Latitude Latitude -120 0 0 37 28 33 4 16 51 30 188 -31 36 31 16 38 27 22 35 49 47 39 11 57 -121 0 0 37 0 18 4 16 40 31 187 -30 36 3 22 37 58 44 35 22 7 38 43 1 -122 0 0 36 32 37 4 16 29 31 186 -30 35 36 1 37 30 41 34 55 1 38 14 41 -123 0 0 36 5 33 4 16 17 32 184 -29 35 9 17 37 3 15 34 28 30 37 46 57 -124 0 0 35 39 5 4 16 6 32 183 -28 34 43 9 36 36 26 34 2 36 37 19 51 -125 0 0 35 13 14 4 15 54 33 182 -28 34 17 37 36 10 15 33 37 18 36 53 24 -126 0 0 34 48 2 4 15 42 33 181 -27 33 52 44 35 44 42 33 12 37 36 27 36 -127 0 0 34 23 29 4 15 30 34 180 -26 33 28 28 35 19 49 32 48 35 36 2 27 -128 0 0 33 59 35 4 15 18 34 179 -25 33 4 52 34 55 36 32 25 11 35 37 59 -129 0 0 33 36 21 4 15 6 35 177 -25 32 41 56 34 32 4 32 2 26 35 14 13 -130 0 0 33 13 48 4 14 53 35 176 -24 32 19 39 34 9 13 31 40 22 34 51 8 -131 0 0 32 51 56 4 14 41 35 175 -23 31 58 4 33 47 4 31 18 57 34 28 45 -132 0 0 32 30 46 4 14 28 35 174 -22 31 37 9 33 25 37 30 58 14 34 7 5 -133 0 0 32 10 18 4 14 16 36 173 -22 31 16 57 33 4 53 30 38 12 33 46 8 -134 0 0 31 50 33 4 14 3 36 171 -21 30 57 26 32 44 52 30 18 51 33 25 54 -135 0 0 31 31 31 4 13 50 36 170 -20 30 38 38 32 25 35 30 0 13 33 6 25 -136 0 0 31 13 12 4 13 38 36 169 -19 30 20 32 32 7 1 29 42 17 32 47 40 -137 0 0 30 55 36 4 13 25 36 168 -18 30 3 10 31 49 12 29 25 4 32 29 40 -138 0 0 30 38 45 4 13 12 36 166 -17 29 46 31 31 32 7 29 8 34 32 12 25 -139 0 0 30 22 38 4 12 59 36 165 -16 29 30 36 31 15 48 28 52 47 31 55 55 -140 0 0 30 7 15 4 12 47 36 164 -15 29 15 25 31 0 13 28 37 44 31 40 11 -141 0 0 29 52 37 4 12 34 36 163 -15 29 0 58 30 45 23 28 23 25 31 25 12 -142 0 0 29 38 45 4 12 21 36 162 -14 28 47 16 30 31 19 28 9 50 31 10 59 -143 0 0 29 25 37 4 12 9 36 160 -13 28 34 18 30 18 1 27 56 59 30 57 33 -144 0 0 29 13 14 4 11 56 36 159 -12 28 22 5 30 5 28 27 44 52 30 44 52 -145 0 0 29 1 37 4 11 43 36 158 -11 28 10 36 29 53 42 27 33 30 30 32 58 -146 0 0 28 50 45 4 11 31 36 157 -10 27 59 53 29 42 41 27 22 53 30 21 51 -147 0 0 28 40 39 4 11 19 36 156 -9 27 49 55 29 32 27 27 13 0 30 11 30 -148 0 0 28 31 19 4 11 6 35 154 -8 27 40 41 29 22 59 27 3 52 30 1 56 -149 0 0 28 22 44 4 10 54 35 153 -7 27 32 13 29 14 17 26 55 28 29 53 9 -150 0 0 28 14 55 4 10 42 35 152 -6 27 24 31 29 6 21 26 47 50 29 45 8 -151 0 0 28 7 52 4 10 30 34 151 -5 27 17 33 28 59 12 26 40 56 29 37 54 -152 0 0 28 1 34 4 10 18 34 150 -5 27 11 21 28 52 49 26 34 48 29 31 27 -153 0 0 27 56 3 4 10 6 34 149 -4 27 5 54 28 47 13 26 29 24 29 25 47 -154 0 0 27 51 17 4 9 55 33 148 -3 27 1 12 28 42 23 26 24 45 29 20 53 -155 0 0 27 47 17 4 9 43 33 147 -2 26 57 16 28 38 19 26 20 52 29 16 46 -156 0 0 27 44 3 4 9 32 32 146 -1 26 54 5 28 35 1 26 17 43 29 13 26 Uncertainty in time = +/- 5 secs Prediction of 2009 Sep 18.0 Data for the target star ------------------------ * name: TYC 6341-00068-1 * constellation : Capricornus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 20 31 44.9217 DE: -21 58 46.551 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .025, .035 ) * V mag [mag]: 11.1 * B mag [mag]: 11.6 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (140) Siwa approx. diameter [km]: 110 approx. diameter ["]: .098 distance from Earth [AU]: 1.54400 * orbital information: orbit source: Preston date of fit: 2009 Sep 17 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1339 number of rejected observations: 179 time covered by the observations: 1900 Apr 26 - 2009 Sep 16 1 sigma uncertainty ellipse (major, minor, PA): 0.019, 0.009, 80° remarks: * orbital elements for (140) Siwa : Mean anomaly = 15.75453990 deg Arg. of pericenter = 197.22623127 deg Long. of node = 107.29264349 deg Inclination = 3.18711938 deg Eccentricity = 0.21734882 Semimajor axis = 2.73316404 AU Perihelion dist = 2.13911406 AU Mag: H = 8.47, G = 0.15 Epoch of elements : MJD 55106.17500000 TDT (2009 Oct 02.175) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Oct 2 140 Siwa 4h 12.9m UT 11.1 20 31 44.922-21 58 46.55TYC 6341-00068-1 11.6 12.1 110 13.3 1.544 1.851 6.64 -126.3007 -21.980 114.14 -3.61 4.2145 -0.20061 0.77863 4.51654 1.16548 0.00469 0.00131 2000 14.4076182009 926.00000197.226231107.292643 3.1871190.21734882 2.7331640 2.1391141 8.3 5.00.15 RATE 2.1812500 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.036 0.032 359 1.37 0.036 0 55092.0020091002_0068-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2009 Sep 17, 21:53 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org