IOTA/IOTA-ES occultation update for (385) Ilmatar / TYC 7334-00546-1 event on 2010 Feb 06, 20:52 UT Visible from W Australia Summary ------- On 2010 Feb 06 UT, the 92 km diameter asteroid (385) Ilmatar will occult a 10.8 mag star in the constellation Scorpius for observers along a path across W Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 12.8 mag (the magnitude of the asteroid) for at most 3.3 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: 65 * date and approx. time of event: 2010 Feb 06, 20:49 - 2010 Feb 06, 20:51 UT * magnitude of target star: 10.8 * magnitude drop [mag]: 2.2 * estimated maximum duration [s]: 3.3 * Moon: 41 % sunlit, 10° distance * Sun: 72° distance * rough path description: W Australia The occultation path -------------------- * approximate projected width [km]: 94 * 1 sigma uncertainty interval [path widths]: +/- 0.92 * 1 sigma uncertainty interval [seconds]: +/- 1.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .029 +/- .044) * 1 sigma uncertainty ellipse (major, minor, PA): ( .044", .029", 1° ) * approx speed of asteroid's shadow [km/s]: 27.9194 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 7334-00546-1 by 385 Ilmatar on 2010 Feb 6 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 71 0 0 10 24 58 20 49 10 1 123 -70 9 54 24 10 55 28 8 57 58 11 51 24 72 0 0 9 45 29 20 49 10 2 123 -69 9 14 46 10 16 8 8 18 3 11 12 22 73 0 0 9 5 18 20 49 11 3 124 -68 8 34 26 9 36 6 7 37 25 10 32 36 74 0 0 8 24 25 20 49 11 4 124 -67 7 53 23 8 55 22 6 56 6 9 52 9 75 0 0 7 42 50 20 49 11 6 124 -65 7 11 39 8 13 56 6 14 5 9 10 59 76 0 0 7 0 34 20 49 12 7 124 -64 6 29 15 7 31 50 5 31 23 8 29 9 77 0 0 6 17 39 20 49 12 8 124 -63 5 46 10 6 49 3 4 48 2 7 46 39 78 0 0 5 34 4 20 49 13 9 124 -62 5 2 26 6 5 37 4 4 2 7 3 29 79 0 0 4 49 51 20 49 14 11 124 -61 4 18 5 5 21 33 3 19 24 6 19 41 80 0 0 4 5 2 20 49 15 12 124 -59 3 33 6 4 36 52 2 34 10 5 35 15 81 0 0 3 19 36 20 49 16 13 124 -58 2 47 32 3 51 35 1 48 20 4 50 13 82 0 0 2 33 36 20 49 17 14 124 -57 2 1 24 3 5 43 1 1 56 4 4 36 83 0 0 1 47 2 20 49 19 16 124 -56 1 14 42 2 19 17 0 14 59 3 18 26 84 0 0 0 59 57 20 49 20 17 124 -55 0 27 29 1 32 20 - 0 32 29 2 31 42 85 0 0 0 12 21 20 49 22 18 124 -53 - 0 20 14 0 44 52 - 1 20 26 1 44 28 86 0 0 - 0 35 43 20 49 23 19 124 -52 - 1 8 26 - 0 3 5 - 2 8 52 0 56 45 87 0 0 - 1 24 14 20 49 25 21 124 -51 - 1 57 4 - 0 51 29 - 2 57 43 0 8 34 88 0 0 - 2 13 11 20 49 27 22 124 -50 - 2 46 8 - 1 40 19 - 3 46 59 - 0 40 4 89 0 0 - 3 2 31 20 49 29 23 124 -48 - 3 35 34 - 2 29 32 - 4 36 38 - 1 29 5 90 0 0 - 3 52 12 20 49 31 25 124 -47 - 4 25 21 - 3 19 7 - 5 26 37 - 2 18 29 91 0 0 - 4 42 12 20 49 33 26 124 -46 - 5 15 28 - 4 9 2 - 6 16 54 - 3 8 13 92 0 0 - 5 32 30 20 49 36 27 124 -44 - 6 5 51 - 4 59 15 - 7 7 27 - 3 58 16 93 0 0 - 6 23 3 20 49 38 28 124 -43 - 6 56 29 - 5 49 43 - 7 58 15 - 4 48 35 94 0 0 - 7 13 49 20 49 41 30 123 -42 - 7 47 20 - 6 40 24 - 8 49 14 - 5 39 7 95 0 0 - 8 4 45 20 49 44 31 123 -41 - 8 38 20 - 7 31 16 - 9 40 22 - 6 29 52 96 0 0 - 8 55 50 20 49 46 32 123 -39 - 9 29 29 - 8 22 17 -10 31 38 - 7 20 46 97 0 0 - 9 47 1 20 49 49 34 123 -38 -10 20 43 - 9 13 24 -11 22 58 - 8 11 47 98 0 0 -10 38 15 20 49 52 35 122 -37 -11 12 0 -10 4 36 -12 14 20 - 9 2 53 99 0 0 -11 29 30 20 49 55 36 122 -35 -12 3 17 -10 55 48 -13 5 43 - 9 54 2 100 0 0 -12 20 44 20 49 59 37 122 -34 -12 54 33 -11 47 1 -13 57 2 -10 45 10 101 0 0 -13 11 55 20 50 2 39 121 -33 -13 45 45 -12 38 10 -14 48 17 -11 36 17 102 0 0 -14 2 59 20 50 5 40 121 -32 -14 36 51 -13 29 13 -15 39 23 -12 27 18 103 0 0 -14 53 55 20 50 9 41 120 -30 -15 27 47 -14 20 8 -16 30 20 -13 18 13 104 0 0 -15 44 40 20 50 12 43 120 -29 -16 18 32 -15 10 53 -17 21 5 -14 8 58 105 0 0 -16 35 11 20 50 16 44 119 -28 -17 9 3 -16 1 26 -18 11 35 -14 59 31 106 0 0 -17 25 28 20 50 19 45 119 -27 -17 59 18 -16 51 43 -19 1 48 -15 49 51 107 0 0 -18 15 26 20 50 23 46 118 -25 -18 49 15 -17 41 43 -19 51 42 -16 39 54 108 0 0 -19 5 5 20 50 27 48 118 -24 -19 38 51 -18 31 24 -20 41 14 -17 29 38 109 0 0 -19 54 21 20 50 31 49 117 -23 -20 28 5 -19 20 43 -21 30 23 -18 19 1 110 0 0 -20 43 13 20 50 35 50 116 -22 -21 16 54 -20 9 38 -22 19 7 -19 8 2 111 0 0 -21 31 40 20 50 38 51 116 -20 -22 5 17 -20 58 8 -23 7 23 -19 56 38 112 0 0 -22 19 38 20 50 42 52 115 -19 -22 53 11 -21 46 10 -23 55 10 -20 44 48 113 0 0 -23 7 6 20 50 46 54 114 -18 -23 40 35 -22 33 43 -24 42 25 -21 32 29 114 0 0 -23 54 3 20 50 50 55 113 -17 -24 27 27 -23 20 45 -25 29 8 -22 19 39 115 0 0 -24 40 27 20 50 54 56 112 -16 -25 13 46 -24 7 14 -26 15 17 -23 6 18 116 0 0 -25 26 17 20 50 59 57 111 -15 -25 59 30 -24 53 9 -27 0 50 -23 52 23 117 0 0 -26 11 30 20 51 3 58 110 -13 -26 44 37 -25 38 28 -27 45 46 -24 37 53 118 0 0 -26 56 6 20 51 7 59 109 -12 -27 29 7 -26 23 11 -28 30 4 -25 22 47 119 0 0 -27 40 4 20 51 11 60 108 -11 -28 12 58 -27 7 15 -29 13 42 -26 7 4 120 0 0 -28 23 22 20 51 15 61 107 -10 -28 56 8 -27 50 40 -29 56 40 -26 50 42 121 0 0 -29 5 59 20 51 19 62 105 -9 -29 38 38 -28 33 25 -30 38 56 -27 33 40 122 0 0 -29 47 55 20 51 23 63 104 -8 -30 20 27 -29 15 28 -31 20 30 -28 15 57 123 0 0 -30 29 9 20 51 27 64 102 -7 -31 1 33 -29 56 50 -32 1 21 -28 57 33 124 0 0 -31 9 40 20 51 31 65 101 -6 -31 41 55 -30 37 29 -32 41 29 -29 38 27 125 0 0 -31 49 27 20 51 35 66 99 -5 -32 21 34 -31 17 24 -33 20 52 -30 18 37 126 0 0 -32 28 30 20 51 39 67 98 -4 -33 0 29 -31 56 36 -33 59 31 -30 58 5 127 0 0 -33 6 49 20 51 43 68 96 -3 -33 38 38 -32 35 3 -34 37 24 -31 36 48 128 0 0 -33 44 23 20 51 47 69 94 -2 -34 16 3 -33 12 46 -35 14 33 -32 14 47 129 0 0 -34 21 11 20 51 51 70 92 -1 -34 52 43 -33 49 44 -35 50 55 -32 52 1 Uncertainty in time = +/- 3 secs Prediction of 2010 Jan 26.0 Data for the target star ------------------------ * name: TYC 7334-00546-1 * constellation : Scorpius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 16 09 25.7085 DE: -32 23 21.728 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .024, .043 ) * V mag [mag]: 10.8 * B mag [mag]: 11.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (385) Ilmatar approx. diameter [km]: 92 approx. diameter ["]: .046 distance from Earth [AU]: 2.73900 * orbital information: orbit source: Preston date of fit: 2009 Oct 19 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 739 number of rejected observations: 116 time covered by the observations: 1904 May 06 - 2009 May 26 1 sigma uncertainty ellipse (major, minor, PA): 0.017, 0.009, 103° remarks: * orbital elements for (385) Ilmatar : Mean anomaly = 41.77206578 deg Arg. of pericenter = 187.86852102 deg Long. of node = 345.22265826 deg Inclination = 13.56277881 deg Eccentricity = 0.12572029 Semimajor axis = 2.84795809 AU Perihelion dist = 2.48991198 AU Mag: H = 7.46, G = 0.15 Epoch of elements : MJD 55233.87000000 TDT (2010 Feb 06.870) ------ occelmnt file for Occult BEGIN ----------------------------------- 2010 Feb 6 385 Ilmatar 20h 52.9m UT 10.8 16 9 25.708-32 23 21.73TYC 7334-00546-1 11.0 12.8 92 3.3 2.739 3.641 -20.79 152.2533 -32.384 -129.70 -15.45 20.8814 -0.08547 -0.17898 14.36702 -6.47453 -0.00552 0.00068 2000 40.9784422010 2 3.00000187.868521345.222658 13.5627790.12572029 2.8479581 2.4899120 7.5 5.00.15 RATE 2.0507080 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.044 0.029 1 1.92 0.043 0 055222.0020100206_0546-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2009 Oct 19, 21:07 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org