IOTA/IOTA-ES occultation update for (87) Sylvia / UCAC2 40324231 event on 2012 Oct 16, 07:08 UT Visible from S Atlantic Ocean Summary ------- On 2012 Oct 16 UT, the 263 km diameter asteroid (87) Sylvia will occult a 10.9 mag star in the constellation Gemini for observers along a path across S Atlantic Ocean. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 12.9 mag (the magnitude of the asteroid) for at most 50.2 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: 80 * date and approx. time of event: 2012 Oct 16, 06:50 - 2012 Oct 16, 07:06 UT * geocentric midpoint of event [JD]: 2456216.7970625 * magnitude of target star: 10.9 * magnitude drop [mag]: 2.2 * estimated maximum duration [s]: 50.2 * Moon: 1 % sunlit, 120° distance * Sun: 110° distance * rough path description: S Atlantic Ocean The occultation path -------------------- * approximate projected width [km]: 315 * 1 sigma uncertainty interval [path widths]: +/- 0.68 * 1 sigma uncertainty interval [seconds]: +/- 31.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .078 +/- .083) * 1 sigma uncertainty ellipse (major, minor, PA): ( .083", .078", 360° ) * approx speed of asteroid's shadow [km/s]: 5.2301 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 40324231 by 87 Sylvia on 2012 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 ' " Longitude Longitude Longitude Longitude - 70 49 55 -60 0 0 6 50 51 0 33 -16 - 67 32 18 ... .. .. - 63 6 3 ... .. .. - 69 33 4 -59 0 0 6 50 52 2 32 -16 - 66 22 1 - 72 46 6 - 62 4 10 ... .. .. - 68 19 25 -58 0 0 6 50 53 3 31 -16 - 65 14 23 - 71 26 6 - 61 4 17 ... .. .. - 67 8 37 -57 0 0 6 50 54 4 30 -17 - 64 9 8 - 70 9 28 - 60 6 12 ... .. .. - 66 0 24 -56 0 0 6 50 57 5 29 -17 - 63 6 2 - 68 55 52 - 59 9 45 - 72 57 10 - 64 54 30 -55 0 0 6 51 0 6 28 -17 - 62 4 52 - 67 45 0 - 58 14 45 - 71 39 6 - 63 50 42 -54 0 0 6 51 3 8 27 -18 - 61 5 28 - 66 36 35 - 57 21 4 - 70 24 3 - 62 48 47 -53 0 0 6 51 8 9 26 -18 - 60 7 38 - 65 30 25 - 56 28 35 - 69 11 44 - 61 48 35 -52 0 0 6 51 12 10 25 -18 - 59 11 15 - 64 26 15 - 55 37 10 - 68 1 53 - 60 49 56 -51 0 0 6 51 18 11 25 -18 - 58 16 9 - 63 23 55 - 54 46 43 - 66 54 17 - 59 52 42 -50 0 0 6 51 24 12 24 -18 - 57 22 14 - 62 23 16 - 53 57 8 - 65 48 43 - 58 56 46 -49 0 0 6 51 30 13 23 -19 - 56 29 23 - 61 24 7 - 53 8 20 - 64 45 0 - 58 1 59 -48 0 0 6 51 38 15 22 -19 - 55 37 30 - 60 26 21 - 52 20 15 - 63 42 58 - 57 8 16 -47 0 0 6 51 45 16 22 -19 - 54 46 29 - 59 29 50 - 51 32 47 - 62 42 29 - 56 15 31 -46 0 0 6 51 54 17 21 -19 - 53 56 15 - 58 34 29 - 50 45 52 - 61 43 25 - 55 23 38 -45 0 0 6 52 3 18 20 -19 - 53 6 44 - 57 40 9 - 49 59 28 - 60 45 37 - 54 32 33 -44 0 0 6 52 12 19 19 -19 - 52 17 51 - 56 46 46 - 49 13 29 - 59 49 0 - 53 42 9 -43 0 0 6 52 23 20 19 -19 - 51 29 32 - 55 54 15 - 48 27 53 - 58 53 26 - 52 52 25 -42 0 0 6 52 33 22 18 -19 - 50 41 43 - 55 2 30 - 47 42 36 - 57 58 51 - 52 3 14 -41 0 0 6 52 45 23 17 -19 - 49 54 20 - 54 11 27 - 46 57 35 - 57 5 9 - 51 14 33 -40 0 0 6 52 57 24 17 -19 - 49 7 21 - 53 21 2 - 46 12 47 - 56 12 16 - 50 26 19 -39 0 0 6 53 9 25 16 -19 - 48 20 41 - 52 31 10 - 45 28 10 - 55 20 5 - 49 38 28 -38 0 0 6 53 22 26 15 -19 - 47 34 17 - 51 41 48 - 44 43 41 - 54 28 34 - 48 50 56 -37 0 0 6 53 36 27 14 -19 - 46 48 7 - 50 52 52 - 43 59 16 - 53 37 38 - 48 3 41 -36 0 0 6 53 51 28 14 -19 - 46 2 7 - 50 4 19 - 43 14 53 - 52 47 12 - 47 16 40 -35 0 0 6 54 5 30 13 -18 - 45 16 15 - 49 16 5 - 42 30 30 - 51 57 14 - 46 29 48 -34 0 0 6 54 21 31 12 -18 - 44 30 27 - 48 28 7 - 41 46 4 - 51 7 40 - 45 43 5 -33 0 0 6 54 37 32 12 -18 - 43 44 41 - 47 40 22 - 41 1 32 - 50 18 27 - 44 56 26 -32 0 0 6 54 54 33 11 -18 - 42 58 55 - 46 52 47 - 40 16 52 - 49 29 31 - 44 9 48 -31 0 0 6 55 11 34 10 -18 - 42 13 5 - 46 5 19 - 39 32 2 - 48 40 48 - 43 23 9 -30 0 0 6 55 29 35 9 -17 - 41 27 9 - 45 17 54 - 38 46 58 - 47 52 16 - 42 36 27 -29 0 0 6 55 47 36 8 -17 - 40 41 3 - 44 30 31 - 38 1 37 - 47 3 53 - 41 49 38 -28 0 0 6 56 6 37 7 -17 - 39 54 47 - 43 43 6 - 37 15 58 - 46 15 34 - 41 2 39 -27 0 0 6 56 26 38 7 -16 - 39 8 15 - 42 55 36 - 36 29 57 - 45 27 16 - 40 15 28 -26 0 0 6 56 46 39 6 -16 - 38 21 26 - 42 7 59 - 35 43 32 - 44 38 58 - 39 28 1 -25 0 0 6 57 7 41 5 -15 - 37 34 17 - 41 20 11 - 34 56 39 - 43 50 35 - 38 40 16 -24 0 0 6 57 28 42 4 -15 - 36 46 44 - 40 32 10 - 34 9 15 - 43 2 6 - 37 52 10 -23 0 0 6 57 50 43 3 -14 - 35 58 44 - 39 43 52 - 33 21 17 - 42 13 26 - 37 3 39 -22 0 0 6 58 13 44 1 -14 - 35 10 15 - 38 55 15 - 32 32 42 - 41 24 33 - 36 14 40 -21 0 0 6 58 36 45 0 -13 - 34 21 13 - 38 6 15 - 31 43 26 - 40 35 24 - 35 25 10 -20 0 0 6 59 0 46 359 -13 - 33 31 33 - 37 16 49 - 30 53 24 - 39 45 56 - 34 35 5 -19 0 0 6 59 24 47 358 -12 - 32 41 14 - 36 26 53 - 30 2 33 - 38 56 4 - 33 44 22 -18 0 0 6 59 49 48 357 -11 - 31 50 9 - 35 36 24 - 29 10 49 - 38 5 47 - 32 52 56 -17 0 0 7 0 15 49 355 -11 - 30 58 16 - 34 45 19 - 28 18 6 - 37 15 0 - 32 0 43 -16 0 0 7 0 41 49 354 -10 - 30 5 29 - 33 53 32 - 27 24 20 - 36 23 40 - 31 7 38 -15 0 0 7 1 8 50 352 -9 - 29 11 44 - 33 1 1 - 26 29 24 - 35 31 42 - 30 13 38 -14 0 0 7 1 35 51 351 -9 - 28 16 55 - 32 7 40 - 25 33 13 - 34 39 3 - 29 18 36 -13 0 0 7 2 4 52 349 -8 - 27 20 57 - 31 13 25 - 24 35 40 - 33 45 39 - 28 22 27 -12 0 0 7 2 32 53 347 -7 - 26 23 43 - 30 18 10 - 23 36 38 - 32 51 25 - 27 25 4 -11 0 0 7 3 2 53 345 -6 - 25 25 6 - 29 21 51 - 22 35 58 - 31 56 15 - 26 26 22 -10 0 0 7 3 32 54 343 -5 - 24 25 0 - 28 24 20 - 21 33 30 - 31 0 5 - 25 26 12 - 9 0 0 7 4 3 55 341 -4 - 23 23 14 - 27 25 32 - 20 29 5 - 30 2 49 - 24 24 27 - 8 0 0 7 4 35 55 339 -3 - 22 19 40 - 26 25 19 - 19 22 31 - 29 4 20 - 23 20 57 - 7 0 0 7 5 7 56 337 -2 - 21 14 7 - 25 23 33 - 18 13 33 - 28 4 32 - 22 15 32 - 6 0 0 7 5 40 56 334 -1 - 20 6 24 - 24 20 6 - 17 1 57 - 27 3 18 - 21 8 0 - 5 0 0 7 6 14 56 332 0 - 18 56 15 - 23 14 47 - 15 47 24 - 26 0 29 Uncertainty in time = +/- 35 secs Prediction of 2012 Oct 8.0 Data for the target star ------------------------ * name: UCAC2 40324231 * constellation : Gemini * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 14 38.4897 DE: +24 26 44.803 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .077, .083 ) * V mag [mag]: 10.9 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (87) Sylvia approx. diameter [km]: 263 approx. diameter ["]: .119 distance from Earth [AU]: 3.05500 * orbital information: orbit source: Preston date of fit: 2012 Oct 07 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 2201 number of rejected observations: 103 time covered by the observations: 1909 Apr 21 - 2012 Oct 05 1 sigma uncertainty ellipse (major, minor, PA): 0.011, 0.007, 80° remarks: * orbital elements for (87) Sylvia : Mean anomaly = 89.24643255 deg Arg. of pericenter = 265.60384575 deg Long. of node = 73.14309994 deg Inclination = 10.88631581 deg Eccentricity = 0.08736828 Semimajor axis = 3.49722295 AU Perihelion dist = 3.19167658 AU Mag: H = 6.70, G = 0.15 Epoch of elements : MJD 56216.29700000 TDT (2012 Oct 16.297) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 16 87 Sylvia 7h 7.8m UT 10.9 6 14 38.490 24 26 44.80UCAC2 40324231 0.0 12.9 263 50.2 3.055 0.482 5.36 -38.4910 24.444 69.44 -9.06 7.1295 0.34601 -0.42581 2.28979 1.86317 -0.00561 0.00011 2000 88.29746220121010.00000265.603846 73.143100 10.8863160.08736828 3.4972230 3.1916766 6.9 5.00.15 RATE 1.5070210 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.083 0.078 360 1.68 0.081 2 7 706 18 1356 0-3 3 056208.0020121016_324231 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Oct 07, 18:53 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org