IOTA/IOTA-ES occultation update for (18) Melpomene / TYC 6288-00566-1 event on 2012 Oct 17, 13:44 UT Visible from China Summary ------- On 2012 Oct 17 UT, the 140 km diameter asteroid (18) Melpomene will occult a 11.6 mag star in the constellation Sagittarius for observers along a path across China. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.4 mag to 10.7 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: 85 * date and approx. time of event: 2012 Oct 17, 13:43 - 2012 Oct 17, 13:45 UT * geocentric midpoint of event [JD]: 2456218.07215833 * magnitude of target star: 11.6 * magnitude drop [mag]: 0.4 * estimated maximum duration [s]: 5.6 * Moon: 6 % sunlit, 48° distance * Sun: 76° distance * rough path description: China The occultation path -------------------- * approximate projected width [km]: 301 * 1 sigma uncertainty interval [path widths]: +/- 0.59 * 1 sigma uncertainty interval [seconds]: +/- 3.0 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .053 +/- .056) * 1 sigma uncertainty ellipse (major, minor, PA): ( .056", .053", 0° ) * approx speed of asteroid's shadow [km/s]: 25.1606 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6288-00566-1 by 18 Melpomene on 2012 Oct 17 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 Latitude Latitude Latitude Latitude 52 0 0 43 35 43 13 43 38 27 184 -1 42 13 28 45 2 2 40 40 53 46 50 9 53 0 0 43 26 26 13 43 41 27 185 -1 42 4 24 44 52 30 40 32 2 46 40 15 54 0 0 43 17 44 13 43 45 27 186 -2 41 55 54 44 43 34 40 23 44 46 31 0 55 0 0 43 9 37 13 43 48 27 187 -3 41 47 58 44 35 14 40 15 59 46 22 21 56 0 0 43 2 5 13 43 51 28 188 -3 41 40 37 44 27 30 40 8 49 46 14 21 57 0 0 42 55 9 13 43 55 28 189 -4 41 33 50 44 20 23 40 2 12 46 6 58 58 0 0 42 48 49 13 43 58 27 190 -5 41 27 39 44 13 53 39 56 10 46 0 14 59 0 0 42 43 4 13 44 1 27 191 -5 41 22 2 44 7 59 39 50 41 45 54 7 60 0 0 42 37 55 13 44 5 27 192 -6 41 17 0 44 2 42 39 45 47 45 48 39 61 0 0 42 33 22 13 44 8 27 193 -7 41 12 34 43 58 2 39 41 27 45 43 48 62 0 0 42 29 26 13 44 11 27 194 -8 41 8 42 43 53 59 39 37 41 45 39 36 63 0 0 42 26 5 13 44 14 27 195 -8 41 5 26 43 50 32 39 34 30 45 36 2 64 0 0 42 23 20 13 44 18 27 196 -9 41 2 45 43 47 43 39 31 53 45 33 7 65 0 0 42 21 11 13 44 21 27 197 -10 41 0 40 43 45 31 39 29 51 45 30 50 66 0 0 42 19 39 13 44 24 26 199 -11 40 59 10 43 43 56 39 28 23 45 29 11 67 0 0 42 18 43 13 44 27 26 200 -11 40 58 15 43 42 58 39 27 30 45 28 11 68 0 0 42 18 23 13 44 31 26 201 -12 40 57 56 43 42 37 39 27 11 45 27 49 69 0 0 42 18 39 13 44 34 26 202 -13 40 58 12 43 42 54 39 27 27 45 28 5 70 0 0 42 19 31 13 44 37 25 203 -14 40 59 3 43 43 47 39 28 18 45 29 0 71 0 0 42 21 0 13 44 40 25 204 -14 41 0 30 43 45 17 39 29 43 45 30 33 72 0 0 42 23 4 13 44 43 25 205 -15 41 2 32 43 47 25 39 31 42 45 32 45 73 0 0 42 25 45 13 44 46 24 206 -16 41 5 9 43 50 9 39 34 16 45 35 35 74 0 0 42 29 1 13 44 49 24 207 -17 41 8 21 43 53 30 39 37 24 45 39 2 75 0 0 42 32 54 13 44 52 24 208 -17 41 12 9 43 57 28 39 41 6 45 43 9 76 0 0 42 37 22 13 44 55 23 208 -18 41 16 31 44 2 3 39 45 23 45 47 53 77 0 0 42 42 26 13 44 57 23 209 -19 41 21 29 44 7 15 39 50 14 45 53 15 78 0 0 42 48 5 13 45 0 22 210 -20 41 27 1 44 13 3 39 55 38 45 59 15 79 0 0 42 54 20 13 45 3 22 211 -20 41 33 8 44 19 27 40 1 37 46 5 53 80 0 0 43 1 11 13 45 6 21 212 -21 41 39 49 44 26 28 40 8 9 46 13 8 81 0 0 43 8 37 13 45 8 21 213 -22 41 47 5 44 34 5 40 15 15 46 21 1 82 0 0 43 16 37 13 45 11 20 214 -22 41 54 56 44 42 18 40 22 54 46 29 31 83 0 0 43 25 13 13 45 13 20 215 -23 42 3 20 44 51 7 40 31 7 46 38 39 84 0 0 43 34 23 13 45 16 19 216 -24 42 12 18 45 0 32 40 39 53 46 48 23 85 0 0 43 44 8 13 45 18 19 217 -25 42 21 50 45 10 32 40 49 11 46 58 45 86 0 0 43 54 28 13 45 20 18 217 -25 42 31 55 45 21 7 40 59 3 47 9 43 87 0 0 44 5 21 13 45 22 18 218 -26 42 42 34 45 32 18 41 9 26 47 21 18 88 0 0 44 16 49 13 45 24 17 219 -27 42 53 46 45 44 3 41 20 22 47 33 29 89 0 0 44 28 50 13 45 26 16 220 -27 43 5 31 45 56 23 41 31 50 47 46 16 90 0 0 44 41 24 13 45 28 16 221 -28 43 17 48 46 9 17 41 43 50 47 59 39 91 0 0 44 54 31 13 45 30 15 222 -29 43 30 37 46 22 46 41 56 21 48 13 37 92 0 0 45 8 12 13 45 32 14 222 -29 43 43 59 46 36 48 42 9 23 48 28 11 93 0 0 45 22 25 13 45 34 14 223 -30 43 57 52 46 51 24 42 22 57 48 43 20 94 0 0 45 37 10 13 45 36 13 224 -30 44 12 16 47 6 33 42 37 0 48 59 3 95 0 0 45 52 26 13 45 37 12 225 -31 44 27 12 47 22 15 42 51 34 49 15 21 96 0 0 46 8 15 13 45 39 12 226 -31 44 42 38 47 38 30 43 6 38 49 32 13 97 0 0 46 24 34 13 45 40 11 226 -32 44 58 35 47 55 16 43 22 11 49 49 39 98 0 0 46 41 25 13 45 41 10 227 -33 45 15 1 48 12 34 43 38 14 50 7 38 99 0 0 46 58 45 13 45 43 10 228 -33 45 31 57 48 30 24 43 54 45 50 26 10 100 0 0 47 16 36 13 45 44 9 229 -34 45 49 22 48 48 45 44 11 44 50 45 14 101 0 0 47 34 56 13 45 45 8 230 -34 46 7 15 49 7 36 44 29 11 51 4 51 102 0 0 47 53 44 13 45 46 8 230 -35 46 25 37 49 26 57 44 47 5 51 24 59 103 0 0 48 13 2 13 45 47 7 231 -35 46 44 26 49 46 47 45 5 26 51 45 38 104 0 0 48 32 47 13 45 47 6 232 -35 47 3 43 50 7 7 45 24 14 52 6 48 105 0 0 48 53 0 13 45 48 5 233 -36 47 23 26 50 27 55 .. .. .. 52 28 29 106 0 0 49 13 39 13 45 49 5 233 -36 47 43 35 50 49 11 .. .. .. 52 50 38 107 0 0 49 34 45 13 45 49 4 234 -37 48 4 9 51 10 54 .. .. .. 53 13 17 108 0 0 49 56 16 13 45 50 3 235 -37 48 25 9 51 33 4 .. .. .. 53 36 25 109 0 0 50 18 13 13 45 50 2 236 -37 48 46 32 51 55 40 .. .. .. 54 0 0 110 0 0 50 40 34 13 45 50 2 236 -37 49 8 19 52 18 42 .. .. .. .. .. .. 111 0 0 51 3 18 13 45 50 1 237 -38 49 30 30 52 42 8 .. .. .. .. .. .. 112 0 0 51 26 26 13 45 51 0 238 -38 49 53 2 .. .. .. .. .. .. .. .. .. Uncertainty in time = +/- 3 secs Prediction of 2012 Oct 8.0 Data for the target star ------------------------ * name: TYC 6288-00566-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 43 33.9364 DE: -19 15 21.404 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .053, .056 ) * V mag [mag]: 11.6 * B mag [mag]: 12.8 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (18) Melpomene approx. diameter [km]: 140 approx. diameter ["]: .095 distance from Earth [AU]: 2.03300 * orbital information: orbit source: Preston date of fit: 2012 Oct 07 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 3926 number of rejected observations: 307 time covered by the observations: 1901 Aug 14 - 2012 Sep 30 1 sigma uncertainty ellipse (major, minor, PA): 0.008, 0.006, 98° remarks: * orbital elements for (18) Melpomene : Mean anomaly = 312.00378243 deg Arg. of pericenter = 228.00208431 deg Long. of node = 150.49553424 deg Inclination = 10.12760959 deg Eccentricity = 0.21809878 Semimajor axis = 2.29562119 AU Perihelion dist = 1.79494902 AU Mag: H = 6.54, G = 0.25 Epoch of elements : MJD 56217.57200000 TDT (2012 Oct 17.572) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 17 18 Melpomene 13h 43.9m UT 11.6 18 43 33.936-19 15 21.40TYC 6288-00566-1 12.8 10.7 140 5.6 2.033 4.308 -7.14 48.4496 -19.253 -29.66 -9.53 13.7318 0.10596 0.87883 14.10496 -1.65197 0.00520 0.00048 2000 309.85810520121010.00000228.002084150.495534 10.1276100.21809878 2.2956212 1.7949490 6.5 5.00.25 RATE 2.8336990 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.056 0.053 0 1.59 0.056 0 0 4-4 056208.0020121017_0566-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Oct 07, 18:58 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org