IOTA/IOTA-ES occultation update for (431) Nephele / TYC 6310-00377-1 event on 2012 Oct 14, 09:07 UT Visible from S Pacific Ocean Summary ------- On 2012 Oct 14 UT, the 79 km diameter asteroid (431) Nephele will occult a 12.1 mag star in the constellation Sagittarius for observers along a path across S Pacific Ocean. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.9 mag to 13.8 mag (the magnitude of the asteroid) for at most 4.3 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: 71 * date and approx. time of event: 2012 Oct 14, 09:07 - 2012 Oct 14, 09:12 UT * geocentric midpoint of event [JD]: 2456214.88014583 * magnitude of target star: 12.1 * magnitude drop [mag]: 1.9 * estimated maximum duration [s]: 4.3 * Moon: 2 % sunlit, 106° distance * Sun: 90° distance * rough path description: S Pacific Ocean The occultation path -------------------- * approximate projected width [km]: 84 * 1 sigma uncertainty interval [path widths]: +/- 0.82 * 1 sigma uncertainty interval [seconds]: +/- 4.1 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .046 +/- .037) * 1 sigma uncertainty ellipse (major, minor, PA): ( .046", .037", 89° ) * approx speed of asteroid's shadow [km/s]: 18.4046 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6310-00377-1 by 431 Nephele on 2012 Oct 14 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 137 0 0 -41 11 57 9 7 26 71 349 0 -41 34 55 -40 49 2 -42 12 42 -40 11 34 138 0 0 -41 3 48 9 7 31 71 347 -1 -41 26 48 -40 40 52 -42 4 39 -40 3 20 139 0 0 -40 55 19 9 7 35 71 344 -2 -41 18 21 -40 32 20 -41 56 14 -39 54 46 140 0 0 -40 46 28 9 7 40 71 341 -2 -41 9 32 -40 23 28 -41 47 29 -39 45 50 141 0 0 -40 37 17 9 7 45 70 338 -3 -41 0 23 -40 14 14 -41 38 22 -39 36 33 142 0 0 -40 27 44 9 7 50 70 335 -4 -40 50 52 -40 4 39 -41 28 55 -39 26 55 143 0 0 -40 17 50 9 7 54 70 332 -5 -40 41 0 -39 54 43 -41 19 7 -39 16 56 144 0 0 -40 7 35 9 7 59 70 329 -6 -40 30 47 -39 44 26 -41 8 58 -39 6 35 145 0 0 -39 56 59 9 8 4 70 327 -6 -40 20 13 -39 33 48 -40 58 27 -38 55 53 146 0 0 -39 46 1 9 8 9 69 324 -7 -40 9 18 -39 22 48 -40 47 36 -38 44 49 147 0 0 -39 34 42 9 8 14 69 321 -8 -39 58 1 -39 11 26 -40 36 23 -38 33 24 148 0 0 -39 23 2 9 8 19 69 319 -9 -39 46 23 -38 59 44 -40 24 49 -38 21 38 149 0 0 -39 11 1 9 8 23 68 316 -10 -39 34 24 -38 47 40 -40 12 54 -38 9 30 150 0 0 -38 58 38 9 8 28 68 314 -10 -39 22 4 -38 35 15 -40 0 38 -37 57 1 151 0 0 -38 45 54 9 8 33 67 312 -11 -39 9 22 -38 22 28 -39 48 0 -37 44 10 152 0 0 -38 32 48 9 8 38 67 309 -12 -38 56 19 -38 9 20 -39 35 2 -37 30 58 153 0 0 -38 19 21 9 8 43 66 307 -13 -38 42 55 -37 55 51 -39 21 42 -37 17 25 154 0 0 -38 5 33 9 8 48 66 305 -14 -38 29 10 -37 42 0 -39 8 0 -37 3 30 155 0 0 -37 51 24 9 8 53 65 303 -15 -38 15 3 -37 27 48 -38 53 58 -36 49 13 156 0 0 -37 36 53 9 8 58 65 301 -15 -38 0 35 -37 13 15 -38 39 34 -36 34 36 157 0 0 -37 22 1 9 9 3 64 299 -16 -37 45 46 -36 58 20 -38 24 50 -36 19 37 158 0 0 -37 6 48 9 9 7 64 297 -17 -37 30 35 -36 43 4 -38 9 44 -36 4 17 159 0 0 -36 51 14 9 9 12 63 295 -18 -37 15 4 -36 27 27 -37 54 17 -35 48 35 160 0 0 -36 35 18 9 9 17 62 294 -19 -36 59 11 -36 11 29 -37 38 28 -35 32 33 161 0 0 -36 19 2 9 9 22 62 292 -20 -36 42 57 -35 55 10 -37 22 19 -35 16 9 162 0 0 -36 2 25 9 9 27 61 290 -20 -36 26 23 -35 38 30 -37 5 49 -34 59 25 163 0 0 -35 45 26 9 9 32 60 289 -21 -36 9 27 -35 21 29 -36 48 58 -34 42 20 164 0 0 -35 28 8 9 9 37 60 287 -22 -35 52 11 -35 4 8 -36 31 47 -34 24 54 165 0 0 -35 10 28 9 9 42 59 286 -23 -35 34 34 -34 46 25 -36 14 15 -34 7 7 166 0 0 -34 52 28 9 9 47 58 284 -24 -35 16 37 -34 28 23 -35 56 22 -33 49 0 167 0 0 -34 34 8 9 9 51 58 283 -25 -34 58 19 -34 10 0 -35 38 9 -33 30 32 168 0 0 -34 15 27 9 9 56 57 282 -26 -34 39 42 -33 51 16 -35 19 35 -33 11 45 169 0 0 -33 56 27 9 10 1 56 280 -27 -34 20 44 -33 32 13 -35 0 42 -32 52 37 170 0 0 -33 37 6 9 10 6 55 279 -27 -34 1 26 -33 12 50 -34 41 28 -32 33 10 171 0 0 -33 17 26 9 10 11 54 278 -28 -33 41 49 -32 53 8 -34 21 55 -32 13 23 172 0 0 -32 57 27 9 10 15 54 277 -29 -33 21 52 -32 33 6 -34 2 3 -31 53 17 173 0 0 -32 37 8 9 10 20 53 276 -30 -33 1 36 -32 12 44 -33 41 51 -31 32 52 174 0 0 -32 16 31 9 10 25 52 274 -31 -32 41 1 -31 52 4 -33 21 20 -31 12 8 175 0 0 -31 55 34 9 10 30 51 273 -32 -32 20 7 -31 31 6 -33 0 31 -30 51 5 176 0 0 -31 34 20 9 10 34 50 272 -33 -31 58 55 -31 9 49 -32 39 22 -30 29 44 177 0 0 -31 12 47 9 10 39 49 271 -34 -31 37 25 -30 48 14 -32 17 56 -30 8 6 178 0 0 -30 50 57 9 10 43 49 270 -35 -31 15 37 -30 26 21 -31 56 12 -29 46 9 179 0 0 -30 28 49 9 10 48 48 270 -36 -30 53 31 -30 4 11 -31 34 10 -29 23 56 180 0 0 -30 6 24 9 10 52 47 269 -37 -30 31 8 -29 41 44 -31 11 51 -29 1 25 -179 0 0 -29 43 43 9 10 57 46 268 -37 -30 8 29 -29 19 1 -30 49 15 -28 38 38 -178 0 0 -29 20 45 9 11 1 45 267 -38 -29 45 33 -28 56 1 -30 26 23 -28 15 35 -177 0 0 -28 57 32 9 11 6 44 266 -39 -29 22 22 -28 32 45 -30 3 15 -27 52 16 -176 0 0 -28 34 3 9 11 10 43 265 -40 -28 58 55 -28 9 14 -29 39 50 -27 28 43 -175 0 0 -28 10 18 9 11 14 42 265 -41 -28 35 12 -27 45 29 -29 16 11 -27 4 54 -174 0 0 -27 46 20 9 11 18 41 264 -42 -28 11 16 -27 21 28 -28 52 17 -26 40 51 -173 0 0 -27 22 7 9 11 23 40 263 -43 -27 47 5 -26 57 14 -28 28 9 -26 16 34 -172 0 0 -26 57 41 9 11 27 40 262 -44 -27 22 40 -26 32 47 -28 3 47 -25 52 4 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Uncertainty in time = +/- 4 secs Prediction of 2012 Oct 8.0 Data for the target star ------------------------ * name: TYC 6310-00377-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 19 33 13.7808 DE: -22 17 04.014 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .043, .035 ) * V mag [mag]: 12.1 * B mag [mag]: 13.8 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (431) Nephele approx. diameter [km]: 79 approx. diameter ["]: .045 distance from Earth [AU]: 2.41200 * orbital information: orbit source: Preston date of fit: 2012 Oct 07 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1302 number of rejected observations: 124 time covered by the observations: 1902 Oct 07 - 2012 Sep 30 1 sigma uncertainty ellipse (major, minor, PA): 0.018, 0.010, 83° remarks: * orbital elements for (431) Nephele : Mean anomaly = 347.93741646 deg Arg. of pericenter = 213.88912859 deg Long. of node = 117.28023321 deg Inclination = 1.82756638 deg Eccentricity = 0.17192547 Semimajor axis = 3.13611671 AU Perihelion dist = 2.59693837 AU Mag: H = 8.83, G = 0.15 Epoch of elements : MJD 56214.38000000 TDT (2012 Oct 14.380) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 14 431 Nephele 9h 7.4m UT 12.1 19 33 13.781-22 17 4.01TYC 6310-00377-1 13.8 13.8 79 4.3 2.412 2.703 5.18 133.1358 -22.286 39.63 -8.36 9.1235 0.04458 -0.32214 10.29056 1.41983 0.00568 0.00091 2000 347.16011420121010.00000213.889129117.280233 1.8275660.17192547 3.1361167 2.5969384 8.7 5.00.15 RATE 1.7746620 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.046 0.037 89 1.82 0.037 0 0-2-4 056208.0020121014_0377-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Oct 07, 18:44 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org