IOTA/IOTA-ES occultation update for (38) Leda / UCAC2 40312365 event on 2010 Mar 22, 10:52 UT Visible from S Australia Summary ------- On 2010 Mar 22 UT, the 116 km diameter asteroid (38) Leda will occult a 11.5 mag star in the constellation Taurus for observers along a path across S Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.8 mag to 13.1 mag (the magnitude of the asteroid) for at most 5.1 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: 70 * date and approx. time of event: 2010 Mar 22, 10:53 - 2010 Mar 22, 10:55 UT * magnitude of target star: 11.5 * magnitude drop [mag]: 1.8 * estimated maximum duration [s]: 5.1 * Moon: 38 % sunlit, 5° distance * Sun: 82° distance * rough path description: S Australia The occultation path -------------------- * approximate projected width [km]: 176 * 1 sigma uncertainty interval [path widths]: +/- 0.84 * 1 sigma uncertainty interval [seconds]: +/- 3.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .060 +/- .059) * 1 sigma uncertainty ellipse (major, minor, PA): ( .060", .059", 90° ) * approx speed of asteroid's shadow [km/s]: 22.8624 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 40312365 by 38 Leda on 2010 Mar 22 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 109 0 0 -26 20 26 10 53 12 39 349 -1 -27 9 49 -25 31 53 -28 34 45 -24 12 0 110 0 0 -26 32 43 10 53 16 38 348 -2 -27 22 13 -25 44 3 -28 47 21 -24 23 59 111 0 0 -26 45 36 10 53 20 38 347 -3 -27 35 13 -25 56 48 -29 0 35 -24 36 34 112 0 0 -26 59 4 10 53 25 38 346 -4 -27 48 49 -26 10 9 -29 14 26 -24 49 43 113 0 0 -27 13 8 10 53 29 37 345 -4 -28 3 2 -26 24 6 -29 28 53 -25 3 27 114 0 0 -27 27 48 10 53 33 37 344 -5 -28 17 49 -26 38 37 -29 43 56 -25 17 45 115 0 0 -27 43 2 10 53 37 36 343 -6 -28 33 12 -26 53 43 -29 59 35 -25 32 38 116 0 0 -27 58 51 10 53 41 36 342 -7 -28 49 11 -27 9 23 -30 15 50 -25 48 5 117 0 0 -28 15 14 10 53 45 35 341 -8 -29 5 43 -27 25 37 -30 32 40 -26 4 5 118 0 0 -28 32 12 10 53 49 35 340 -9 -29 22 51 -27 42 26 -30 50 5 -26 20 38 119 0 0 -28 49 43 10 53 53 34 339 -10 -29 40 32 -27 59 47 -31 8 4 -26 37 45 120 0 0 -29 7 48 10 53 57 33 338 -11 -29 58 47 -28 17 42 -31 26 38 -26 55 24 121 0 0 -29 26 25 10 54 1 33 337 -11 -30 17 36 -28 36 9 -31 45 46 -27 13 36 122 0 0 -29 45 36 10 54 5 32 336 -12 -30 36 57 -28 55 9 -32 5 28 -27 32 19 123 0 0 -30 5 18 10 54 8 31 335 -13 -30 56 51 -29 14 41 -32 25 42 -27 51 34 124 0 0 -30 25 32 10 54 12 31 334 -14 -31 17 17 -29 34 44 -32 46 29 -28 11 20 125 0 0 -30 46 18 10 54 15 30 333 -15 -31 38 14 -29 55 19 -33 7 48 -28 31 37 126 0 0 -31 7 34 10 54 19 29 332 -16 -31 59 42 -30 16 23 -33 29 39 -28 52 23 127 0 0 -31 29 21 10 54 22 29 331 -16 -32 21 41 -30 37 58 -33 52 0 -29 13 40 128 0 0 -31 51 37 10 54 25 28 331 -17 -32 44 11 -31 0 3 -34 14 52 -29 35 25 129 0 0 -32 14 23 10 54 29 27 330 -18 -33 7 9 -31 22 36 -34 38 14 -29 57 40 130 0 0 -32 37 37 10 54 32 26 329 -19 -33 30 36 -31 45 38 -35 2 6 -30 20 22 131 0 0 -33 1 19 10 54 35 26 328 -19 -33 54 32 -32 9 7 -35 26 26 -30 43 32 132 0 0 -33 25 28 10 54 38 25 327 -20 -34 18 55 -32 33 4 -35 51 14 -31 7 8 133 0 0 -33 50 5 10 54 40 24 327 -21 -34 43 45 -32 57 27 -36 16 29 -31 31 11 134 0 0 -34 15 7 10 54 43 23 326 -22 -35 9 1 -33 22 16 -36 42 11 -31 55 40 135 0 0 -34 40 34 10 54 46 22 325 -22 -35 34 42 -33 47 30 -37 8 18 -32 20 33 136 0 0 -35 6 26 10 54 48 21 324 -23 -36 0 49 -34 13 8 -37 34 51 -32 45 50 137 0 0 -35 32 42 10 54 51 21 324 -24 -36 27 19 -34 39 10 -38 1 47 -33 11 31 138 0 0 -35 59 20 10 54 53 20 323 -24 -36 54 12 -35 5 35 -38 29 7 -33 37 35 139 0 0 -36 26 21 10 54 56 19 322 -25 -37 21 27 -35 32 22 -38 56 50 -34 4 0 140 0 0 -36 53 43 10 54 58 18 321 -26 -37 49 4 -35 59 30 -39 24 54 -34 30 47 141 0 0 -37 21 25 10 55 0 17 321 -26 -38 17 2 -36 26 59 -39 53 19 -34 57 54 142 0 0 -37 49 27 10 55 2 16 320 -27 -38 45 18 -36 54 47 -40 22 3 -35 25 20 143 0 0 -38 17 48 10 55 4 15 319 -27 -39 13 54 -37 22 53 -40 51 6 -35 53 4 144 0 0 -38 46 26 10 55 5 15 319 -28 -39 42 47 -37 51 17 -41 20 27 -36 21 7 145 0 0 -39 15 20 10 55 7 14 318 -28 -40 11 56 -38 19 57 -41 50 4 -36 49 25 146 0 0 -39 44 30 10 55 9 13 317 -29 -40 41 22 -38 48 54 -42 19 57 -37 18 0 147 0 0 -40 13 55 10 55 10 12 316 -29 -41 11 1 -39 18 4 -42 50 4 -37 46 49 148 0 0 -40 43 34 10 55 11 11 316 -30 -41 40 54 -39 47 29 -43 20 25 -38 15 52 149 0 0 -41 13 24 10 55 13 10 315 -30 -42 11 0 -40 17 6 -43 50 58 -38 45 8 150 0 0 -41 43 27 10 55 14 9 314 -31 -42 41 17 -40 46 54 -44 21 42 -39 14 36 151 0 0 -42 13 39 10 55 15 8 314 -31 -43 11 44 -41 16 53 -44 52 36 -39 44 14 152 0 0 -42 44 1 10 55 16 8 313 -31 -43 42 20 -41 47 2 -45 23 39 -40 14 2 153 0 0 -43 14 30 10 55 17 7 312 -32 -44 13 4 -42 17 18 -45 54 49 -40 43 58 154 0 0 -43 45 7 10 55 17 6 312 -32 -44 43 54 -42 47 42 -46 26 5 -41 14 2 155 0 0 -44 15 49 10 55 18 5 311 -32 -45 14 50 -43 18 11 -46 57 27 .. .. .. 156 0 0 -44 46 36 10 55 18 4 310 -33 -45 45 50 -43 48 46 -47 28 52 .. .. .. 157 0 0 -45 17 26 10 55 19 3 309 -33 -46 16 54 -44 19 24 -48 0 20 .. .. .. 158 0 0 -45 48 19 10 55 19 2 309 -33 -46 47 59 -44 50 5 -48 31 49 .. .. .. 159 0 0 -46 19 12 10 55 19 1 308 -33 -47 19 5 -45 20 47 .. .. .. .. .. .. 160 0 0 -46 50 6 10 55 19 1 307 -33 .. .. .. -45 51 29 .. .. .. .. .. .. Uncertainty in time = +/- 4 secs Prediction of 2010 Mar 18.0 Data for the target star ------------------------ * name: UCAC2 40312365 * constellation : Taurus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 05 31 26.8599 DE: +24 10 41.980 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .059, .059 ) * V mag [mag]: 11.5 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (38) Leda approx. diameter [km]: 116 approx. diameter ["]: .071 distance from Earth [AU]: 2.23800 * orbital information: orbit source: Preston date of fit: 2010 Mar 18 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1046 number of rejected observations: 109 time covered by the observations: 1904 Sep 19 - 2010 Mar 18 1 sigma uncertainty ellipse (major, minor, PA): 0.013, 0.009, 95° remarks: * orbital elements for (38) Leda : Mean anomaly = 2.22985514 deg Arg. of pericenter = 169.75516155 deg Long. of node = 295.79250638 deg Inclination = 6.97258988 deg Eccentricity = 0.15391796 Semimajor axis = 2.73992953 AU Perihelion dist = 2.31820518 AU Mag: H = 8.37, G = 0.15 Epoch of elements : MJD 55277.45300000 TDT (2010 Mar 22.453) ------ occelmnt file for Occult BEGIN ----------------------------------- 2010 Mar 22 38 Leda 10h 52.3m UT 11.5 5 31 26.860 24 10 41.98UCAC2 40312365 0.0 13.1 116 5.1 2.238 3.695 -3.85 99.9489 24.179 18.66 0.68 10.8715 -0.05261 -0.75027 12.86701 -0.97868 0.00553 0.00028 2000 0.6101872010 315.00000169.755162295.792506 6.9725900.15391796 2.7399295 2.3182052 8.3 5.00.15 RATE 2.1731760 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.060 0.059 90 1.84 0.060 0 055273.0020100322_312365 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2010 Mar 18, 16:23 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org