IOTA/IOTA-ES occultation update for (140) Siwa / TYC 6341-00068-1 event on 2009 Oct 02, 04:12 UT Visible from 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 . 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, 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: 96 % sunlit, 41° distance * Sun: 116° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 185 * 1 sigma uncertainty interval [path widths]: +/- 0.37 * 1 sigma uncertainty interval [seconds]: +/- 4.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .039 +/- .036) * 1 sigma uncertainty ellipse (major, minor, PA): ( .039", .036", 84° ) * approx speed of asteroid's shadow [km/s]: 8.2642 * 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 - 81 59 17 59 0 0 4 20 39 1 222 -34 ... .. .. - 84 9 39 ... .. .. - 85 46 42 - 83 45 52 58 0 0 4 20 39 2 221 -34 - 81 39 22 - 85 53 12 ... .. .. - 87 28 5 - 85 30 40 57 0 0 4 20 37 3 219 -35 - 83 27 0 - 87 35 17 ... .. .. - 89 8 13 - 87 13 59 56 0 0 4 20 35 5 218 -35 - 85 12 51 - 89 16 10 - 83 43 46 - 90 47 22 - 88 56 6 55 0 0 4 20 32 6 216 -36 - 86 57 13 - 90 56 7 - 85 29 53 - 92 25 47 - 90 37 16 54 0 0 4 20 28 8 215 -36 - 88 40 23 - 92 35 22 - 87 14 36 - 94 3 41 - 92 17 43 53 0 0 4 20 24 9 213 -37 - 90 22 37 - 94 14 10 - 88 58 12 - 95 41 19 - 93 57 43 52 0 0 4 20 18 10 212 -37 - 92 4 9 - 95 52 43 - 90 40 55 - 97 18 52 - 95 37 28 51 0 0 4 20 12 12 211 -37 - 93 45 13 - 97 31 16 - 92 23 1 - 98 56 35 - 97 17 12 50 0 0 4 20 5 13 209 -37 - 95 26 2 - 99 10 0 - 94 4 44 -100 34 40 - 98 57 7 49 0 0 4 19 57 15 208 -37 - 97 6 51 -100 49 9 - 95 46 16 -102 13 20 -100 37 28 48 0 0 4 19 48 16 206 -37 - 98 47 52 -102 28 58 - 97 27 51 -103 52 49 -102 18 28 47 0 0 4 19 38 17 205 -37 -100 29 20 -104 9 38 - 99 9 44 -105 33 21 -104 0 22 46 0 0 4 19 27 19 203 -37 -102 11 27 -105 51 27 -100 52 7 -107 15 12 -105 43 24 45 0 0 4 19 15 20 202 -37 -103 54 29 -107 34 38 -102 35 14 -108 58 38 -107 27 51 44 0 0 4 19 1 22 200 -36 -105 38 41 -109 19 32 -104 19 22 -110 43 59 -109 14 0 43 0 0 4 18 47 23 199 -36 -107 24 20 -111 6 25 -106 4 45 -112 31 35 -111 2 13 42 0 0 4 18 32 24 197 -35 -109 11 45 -112 55 42 -107 51 43 -114 21 50 -112 52 52 41 0 0 4 18 15 26 195 -35 -111 1 15 -114 47 46 -109 40 33 -116 15 12 -114 46 23 40 0 0 4 17 57 27 193 -34 -112 53 15 -116 43 9 -111 31 37 -118 12 13 -116 43 16 39 0 0 4 17 37 28 191 -33 -114 48 12 -118 42 25 -113 25 22 -120 13 35 -118 44 9 38 0 0 4 17 16 30 189 -32 -116 46 37 -120 46 18 -115 22 14 -122 20 7 Latitude Latitude Latitude Latitude -120 0 0 37 23 29 4 17 2 30 188 -31 36 26 20 38 22 8 35 44 57 39 6 36 -121 0 0 36 55 14 4 16 51 31 187 -30 35 58 26 37 53 31 35 17 17 38 37 41 -122 0 0 36 27 34 4 16 40 32 186 -30 35 31 7 37 25 29 34 50 12 38 9 21 -123 0 0 36 0 30 4 16 29 32 184 -29 35 4 23 36 58 4 34 23 42 37 41 39 -124 0 0 35 34 3 4 16 17 33 183 -28 34 38 15 36 31 15 33 57 47 37 14 34 -125 0 0 35 8 13 4 16 5 33 182 -28 34 12 44 36 5 5 33 32 30 36 48 7 -126 0 0 34 43 1 4 15 53 33 181 -27 33 47 50 35 39 33 33 7 49 36 22 19 -127 0 0 34 18 28 4 15 41 34 180 -26 33 23 35 35 14 40 32 43 47 35 57 11 -128 0 0 33 54 34 4 15 29 34 179 -26 32 59 59 34 50 28 32 20 23 35 32 44 -129 0 0 33 31 20 4 15 17 35 177 -25 32 37 3 34 26 56 31 57 38 35 8 57 -130 0 0 33 8 47 4 15 5 35 176 -24 32 14 46 34 4 5 31 35 33 34 45 53 -131 0 0 32 46 55 4 14 52 35 175 -23 31 53 10 33 41 56 31 14 9 34 23 30 -132 0 0 32 25 45 4 14 40 36 174 -22 31 32 16 33 20 29 30 53 25 34 1 50 -133 0 0 32 5 17 4 14 27 36 173 -22 31 12 3 32 59 44 30 33 22 33 40 53 -134 0 0 31 45 31 4 14 14 36 171 -21 30 52 31 32 39 43 30 14 1 33 20 39 -135 0 0 31 26 29 4 14 2 36 170 -20 30 33 43 32 20 26 29 55 23 33 1 10 -136 0 0 31 8 9 4 13 49 36 169 -19 30 15 37 32 1 52 29 37 26 32 42 25 -137 0 0 30 50 33 4 13 36 36 168 -18 29 58 14 31 44 2 29 20 12 32 24 24 -138 0 0 30 33 41 4 13 23 36 166 -17 29 41 34 31 26 57 29 3 42 32 7 8 -139 0 0 30 17 34 4 13 11 36 165 -16 29 25 39 31 10 36 28 47 54 31 50 38 -140 0 0 30 2 10 4 12 58 36 164 -16 29 10 27 30 55 1 28 32 50 31 34 53 -141 0 0 29 47 31 4 12 45 36 163 -15 28 55 59 30 40 10 28 18 30 31 19 53 -142 0 0 29 33 38 4 12 32 36 162 -14 28 42 15 30 26 5 28 4 54 31 5 40 -143 0 0 29 20 29 4 12 20 36 160 -13 28 29 16 30 12 46 27 52 2 30 52 12 -144 0 0 29 8 5 4 12 7 36 159 -12 28 17 2 30 0 13 27 39 54 30 39 31 -145 0 0 28 56 27 4 11 55 36 158 -11 28 5 33 29 48 25 27 28 31 30 27 36 -146 0 0 28 45 34 4 11 42 36 157 -10 27 54 48 29 37 23 27 17 52 30 16 27 -147 0 0 28 35 27 4 11 30 36 156 -9 27 44 48 29 27 8 27 7 58 30 6 5 -148 0 0 28 26 5 4 11 17 35 154 -8 27 35 34 29 17 38 26 58 48 29 56 30 -149 0 0 28 17 29 4 11 5 35 153 -7 27 27 4 29 8 55 26 50 24 29 47 41 -150 0 0 28 9 38 4 10 53 35 152 -6 27 19 20 29 0 58 26 42 44 29 39 39 -151 0 0 28 2 34 4 10 41 34 151 -5 27 12 21 28 53 47 26 35 49 29 32 24 -152 0 0 27 56 15 4 10 29 34 150 -5 27 6 7 28 47 23 26 29 39 29 25 55 -153 0 0 27 50 42 4 10 17 34 149 -4 27 0 39 28 41 45 26 24 13 29 20 13 -154 0 0 27 45 54 4 10 6 33 148 -3 26 55 56 28 36 53 26 19 33 29 15 18 -155 0 0 27 41 52 4 9 54 33 147 -2 26 51 57 28 32 48 26 15 37 29 11 10 -156 0 0 27 38 36 4 9 43 32 146 -1 26 48 44 28 29 28 26 12 27 29 7 48 Uncertainty in time = +/- 5 secs [Prediction of 2008 Mar 20.0] 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: 2008 Mar 20 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1225 number of rejected observations: 178 time covered by the observations: 1900 Apr 26 - 2008 Mar 10 1 sigma uncertainty ellipse (major, minor, PA): 0.030, 0.010, 80° remarks: * orbital elements for (140) Siwa : Mean anomaly = 15.75452397 deg Arg. of pericenter = 197.22624283 deg Long. of node = 107.29264025 deg Inclination = 3.18712247 deg Eccentricity = 0.21734882 Semimajor axis = 2.73316407 AU Perihelion dist = 2.13911407 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 13.0m 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 -126.3437 -21.980 114.10 -3.61 4.2173 -0.20152 0.77741 4.51657 1.16549 0.00469 0.00131 2000 14.4076022009 926.00000197.226243107.292640 3.1871220.21734882 2.7331641 2.1391141 8.3 5.00.15 RATE 2.1812500 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.039 0.036 84 1.37 0.036 0 54545.5020091002_0068-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 20, 14:19 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org