IOTA/IOTA-ES occultation update for (106) Dione / UCAC2 20927150 event on 2008 Oct 16, 11:50 UT Visible from Tasmania Summary ------- On 2008 Oct 16 UT, the 147 km diameter asteroid (106) Dione will occult a 11.6 mag star in the constellation Sagittarius for observers along a path across Tasmania. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.0 mag to 13.5 mag (the magnitude of the asteroid) for at most 5.6 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: 82 * date and approx. time of event: 2008 Oct 16, 11:51 - 2008 Oct 16, 11:54 UT * midpoint of event [JD]: 2454755.99355417 * magnitude of target star: 11.6 * magnitude drop [mag]: 2.0 * estimated maximum duration [s]: 5.6 * Moon: 96 % sunlit, 134° distance * Sun: 68° distance * rough path description: Tasmania The occultation path -------------------- * approximate projected width [km]: 176 * 1 sigma uncertainty interval [path widths]: +/- 0.64 * 1 sigma uncertainty interval [seconds]: +/- 3.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .041 +/- .038) * 1 sigma uncertainty ellipse (major, minor, PA): ( .041", .038", 90° ) * approx speed of asteroid's shadow [km/s]: 26.2753 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 20927150 by 106 Dione on 2008 Oct 16 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 103 0 0 -56 52 56 11 51 55 51 306 0 -57 43 44 -56 2 39 -58 49 32 -54 59 1 104 0 0 -56 41 12 11 51 57 51 305 -1 -57 32 9 -55 50 47 -58 38 9 -54 46 58 105 0 0 -56 29 7 11 52 0 50 303 -1 -57 20 13 -55 38 33 -58 26 25 -54 34 33 106 0 0 -56 16 40 11 52 2 50 302 -2 -57 7 55 -55 25 57 -58 14 20 -54 21 46 107 0 0 -56 3 51 11 52 4 50 301 -3 -56 55 15 -55 12 59 -58 1 53 -54 8 36 108 0 0 -55 50 40 11 52 7 49 299 -3 -56 42 14 -54 59 39 -57 49 4 -53 55 5 109 0 0 -55 37 7 11 52 9 49 298 -4 -56 28 50 -54 45 56 -57 35 53 -53 41 10 110 0 0 -55 23 11 11 52 11 48 296 -4 -56 15 4 -54 31 51 -57 22 20 -53 26 54 111 0 0 -55 8 52 11 52 14 48 295 -5 -56 0 55 -54 17 23 -57 8 24 -53 12 14 112 0 0 -54 54 11 11 52 16 48 294 -6 -55 46 24 -54 2 32 -56 54 6 -52 57 11 113 0 0 -54 39 7 11 52 18 47 292 -6 -55 31 30 -53 47 18 -56 39 25 -52 41 45 114 0 0 -54 23 39 11 52 21 47 291 -7 -55 16 12 -53 31 41 -56 24 21 -52 25 56 115 0 0 -54 7 49 11 52 23 46 290 -8 -55 0 32 -53 15 40 -56 8 54 -52 9 43 116 0 0 -53 51 34 11 52 26 46 289 -8 -54 44 28 -52 59 16 -55 53 3 -51 53 7 117 0 0 -53 34 57 11 52 28 45 287 -9 -54 28 0 -52 42 28 -55 36 49 -51 36 7 118 0 0 -53 17 55 11 52 30 45 286 -10 -54 11 8 -52 25 17 -55 20 11 -51 18 43 119 0 0 -53 0 29 11 52 33 44 285 -10 -53 53 53 -52 7 41 -55 3 9 -51 0 56 120 0 0 -52 42 40 11 52 35 44 284 -11 -53 36 14 -51 49 42 -54 45 44 -50 42 44 121 0 0 -52 24 26 11 52 38 43 282 -12 -53 18 10 -51 31 18 -54 27 53 -50 24 8 122 0 0 -52 5 48 11 52 40 43 281 -12 -52 59 42 -51 12 31 -54 9 39 -50 5 9 123 0 0 -51 46 46 11 52 42 42 280 -13 -52 40 50 -50 53 19 -53 51 0 -49 45 45 124 0 0 -51 27 19 11 52 45 42 279 -14 -52 21 33 -50 33 43 -53 31 57 -49 25 57 125 0 0 -51 7 28 11 52 47 41 278 -14 -52 1 52 -50 13 42 -53 12 29 -49 5 45 126 0 0 -50 47 13 11 52 50 40 277 -15 -51 41 47 -49 53 17 -52 52 37 -48 45 8 127 0 0 -50 26 33 11 52 52 40 275 -16 -51 21 17 -49 32 28 -52 32 20 -48 24 8 128 0 0 -50 5 29 11 52 54 39 274 -17 -51 0 22 -49 11 15 -52 11 38 -48 2 43 129 0 0 -49 44 1 11 52 57 39 273 -17 -50 39 3 -48 49 38 -51 50 31 -47 40 54 130 0 0 -49 22 8 11 52 59 38 272 -18 -50 17 20 -48 27 36 -51 29 0 -47 18 42 131 0 0 -48 59 51 11 53 2 37 271 -19 -49 55 12 -48 5 10 -51 7 4 -46 56 6 132 0 0 -48 37 10 11 53 4 37 270 -20 -49 32 39 -47 42 21 -50 44 43 -46 33 6 133 0 0 -48 14 5 11 53 6 36 269 -20 -49 9 43 -47 19 8 -50 21 58 -46 9 42 134 0 0 -47 50 36 11 53 9 35 268 -21 -48 46 23 -46 55 31 -49 58 49 -45 45 56 135 0 0 -47 26 44 11 53 11 35 267 -22 -48 22 38 -46 31 31 -49 35 16 -45 21 46 136 0 0 -47 2 28 11 53 13 34 266 -23 -47 58 30 -46 7 7 -49 11 18 -44 57 14 137 0 0 -46 37 49 11 53 15 33 265 -23 -47 33 59 -45 42 21 -48 46 57 -44 32 19 138 0 0 -46 12 48 11 53 18 32 264 -24 -47 9 4 -45 17 13 -48 22 12 -44 7 1 139 0 0 -45 47 23 11 53 20 32 263 -25 -46 43 47 -44 51 42 -47 57 4 -43 41 22 140 0 0 -45 21 37 11 53 22 31 262 -26 -46 18 7 -44 25 49 -47 31 33 -43 15 22 141 0 0 -44 55 29 11 53 24 30 261 -27 -45 52 5 -43 59 35 -47 5 39 -42 49 0 142 0 0 -44 28 59 11 53 26 29 260 -27 -45 25 42 -43 33 0 -46 39 23 -42 22 18 143 0 0 -44 2 9 11 53 28 29 260 -28 -44 58 57 -43 6 4 -46 12 46 -41 55 16 144 0 0 -43 34 58 11 53 31 28 259 -29 -44 31 51 -42 38 48 -45 45 47 -41 27 54 145 0 0 -43 7 27 11 53 33 27 258 -30 -44 4 24 -42 11 13 -45 18 27 -41 0 13 146 0 0 -42 39 37 11 53 35 26 257 -31 -43 36 38 -41 43 18 -44 50 46 -40 32 14 147 0 0 -42 11 27 11 53 37 25 256 -31 -43 8 33 -41 15 5 -44 22 46 -40 3 56 148 0 0 -41 43 0 11 53 38 24 255 -32 -42 40 9 -40 46 35 -43 54 27 -39 35 22 149 0 0 -41 14 15 11 53 40 24 255 -33 -42 11 28 -40 17 47 -43 25 49 -39 6 31 150 0 0 -40 45 14 11 53 42 23 254 -34 -41 42 28 -39 48 43 -42 56 54 -38 37 23 151 0 0 -40 15 56 11 53 44 22 253 -35 -41 13 13 -39 19 23 -42 27 41 -38 8 1 152 0 0 -39 46 23 11 53 46 21 252 -36 -40 43 41 -38 49 48 -41 58 11 -37 38 24 153 0 0 -39 16 35 11 53 47 20 252 -36 -40 13 54 -38 19 59 -41 28 26 -37 8 34 154 0 0 -38 46 33 11 53 49 19 251 -37 -39 43 53 -37 49 57 -40 58 27 -36 38 31 155 0 0 -38 16 18 11 53 50 18 250 -38 -39 13 39 -37 19 42 -40 28 13 -36 8 15 156 0 0 -37 45 51 11 53 52 17 250 -39 -38 43 12 -36 49 15 -39 57 45 -35 37 49 157 0 0 -37 15 13 11 53 53 16 249 -40 -38 12 33 -36 18 38 -39 27 6 -35 7 12 158 0 0 -36 44 25 11 53 55 15 248 -41 -37 41 44 -35 47 51 -38 56 15 -34 36 26 159 0 0 -36 13 27 11 53 56 15 248 -41 -37 10 45 -35 16 54 -38 25 14 -34 5 32 160 0 0 -35 42 21 11 53 57 14 247 -42 -36 39 37 -34 45 50 -37 54 3 -33 34 30 161 0 0 -35 11 7 11 53 58 13 246 -43 -36 8 20 -34 14 39 -37 22 44 -33 3 22 162 0 0 -34 39 47 11 53 59 12 246 -44 -35 36 57 -33 43 21 -36 51 17 -32 32 8 163 0 0 -34 8 22 11 54 0 11 245 -45 -35 5 29 -33 11 59 -36 19 43 -32 0 49 164 0 0 -33 36 52 11 54 1 10 245 -45 -34 33 55 -32 40 32 -35 48 5 -31 29 27 165 0 0 -33 5 18 11 54 2 9 244 -46 -34 2 17 -32 9 3 -35 16 21 -30 58 2 166 0 0 -32 33 42 11 54 3 8 243 -47 -33 30 36 -31 37 31 -34 44 35 -30 26 36 167 0 0 -32 2 5 11 54 3 7 243 -48 -32 58 54 -31 5 58 -34 12 46 -29 55 9 168 0 0 -31 30 27 11 54 4 6 242 -48 -32 27 11 -30 34 26 -33 40 56 -29 23 43 169 0 0 -30 58 50 11 54 4 5 242 -49 -31 55 28 -30 2 54 -33 9 6 -28 52 18 170 0 0 -30 27 14 11 54 5 4 241 -50 -31 23 47 -29 31 25 -32 37 16 .. .. .. 171 0 0 -29 55 42 11 54 5 3 241 -51 -30 52 8 -28 59 58 -32 5 29 .. .. .. 172 0 0 -29 24 13 11 54 5 2 240 -51 -30 20 33 -28 28 36 -31 33 45 .. .. .. 173 0 0 -28 52 49 11 54 5 1 240 -52 -29 49 2 -27 57 19 -31 2 4 .. .. .. Uncertainty in time = +/- 4 secs [Prediction of 2008 Sep 11.0] Data for the target star ------------------------ * name: UCAC2 20927150 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 07 18.5073 DE: -26 31 26.400 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .039, .037 ) * V mag [mag]: 11.6 * B mag [mag]: 0.0 * Apparent position with proper motion RA(deg): 271.9650137278 DE(deg): -26.5245659758 * Equation of equinoxes (radians) : 0.000046891048367 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (106) Dione approx. diameter [km]: 147 approx. diameter ["]: .059 distance from Earth [AU]: 3.43900 * orbital information: orbit source: Preston date of fit: 2008 Sep 05 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 800 number of rejected observations: 155 time covered by the observations: 1900 May 01 - 2008 Aug 22 1 sigma uncertainty ellipse (major, minor, PA): 0.011, 0.009, 94° remarks: * orbital elements for (106) Dione : Mean anomaly = 276.69422554 deg Arg. of pericenter = 329.00094027 deg Long. of node = 62.34089638 deg Inclination = 4.60209027 deg Eccentricity = 0.17033740 Semimajor axis = 3.17832739 AU Perihelion dist = 2.63693936 AU Mag: H = 7.47, G = 0.15 Epoch of elements : MJD 54755.49300000 TDT (2008 Oct 16.493) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Oct 16 106 Dione 11h 50.7m UT 11.6 18 7 18.507-26 31 26.40UCAC2 20927150 0.0 13.5 147 5.6 3.439 2.825 0.98 68.7766 -26.525 -1.31 -9.12 11.8453 0.01361 -0.55193 14.82555 0.38282 0.00544 -0.00005 2000 275.73875920081011.00000329.000940 62.340896 4.6020900.17033740 3.1783274 2.6369394 7.4 5.00.15 RATE 1.7394270 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.041 0.038 90 1.64 0.038 0 54720.5020081016_927150 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Sep 11, 20:21 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org