IOTA/IOTA-ES occultation update for (877) Walkure / TYC 5589-00155-1 event on 2008 Apr 01, 12:31 UT Visible from Pacific Ocean Summary ------- On 2008 Apr 01 UT, the 38 km diameter asteroid (877) Walkure will occult a 10.2 mag star in the constellation Libra for observers along a path across Pacific Ocean. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.1 mag to 15.3 mag (the magnitude of the asteroid) for at most 4.9 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: 50 * date and approx. time of event: 2008 Apr 01, 12:20 - 2008 Apr 01, 12:44 UT * magnitude of target star: 10.2 * magnitude drop [mag]: 5.1 * estimated maximum duration [s]: 4.9 * Moon: 25 % sunlit, 84° distance * Sun: 143° distance * rough path description: Pacific Ocean The occultation path -------------------- * approximate projected width [km]: 39 * 1 sigma uncertainty interval [path widths]: +/- 1.29 * 1 sigma uncertainty interval [seconds]: +/- 6.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .036 +/- .033) * 1 sigma uncertainty ellipse (major, minor, PA): ( .037", .033", 103° ) * approx speed of asteroid's shadow [km/s]: 7.8509 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 5589-00155-1 by 877 Walkure on 2008 Apr 1 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 126 0 0 34 51 46 12 44 35 1 105 -33 35 2 36 34 40 56 35 30 35 34 13 2 127 0 0 34 38 36 12 44 35 1 105 -34 34 49 28 34 27 45 35 17 30 33 59 48 128 0 0 34 25 2 12 44 35 2 106 -35 34 35 55 34 14 10 35 4 1 33 46 9 129 0 0 34 11 4 12 44 34 3 106 -35 34 21 58 34 0 11 34 50 7 33 32 6 130 0 0 33 56 42 12 44 33 4 107 -36 34 7 37 33 45 47 34 35 50 33 17 39 131 0 0 33 41 55 12 44 33 5 108 -37 33 52 52 33 30 59 34 21 8 33 2 48 132 0 0 33 26 44 12 44 31 6 108 -38 33 37 42 33 15 47 34 6 2 32 47 32 133 0 0 33 11 9 12 44 30 7 109 -39 33 22 8 33 0 10 33 50 32 32 31 52 134 0 0 32 55 10 12 44 29 7 109 -39 33 6 11 32 44 9 33 34 37 32 15 48 135 0 0 32 38 47 12 44 27 8 110 -40 32 49 49 32 27 45 33 18 19 31 59 19 136 0 0 32 21 59 12 44 25 9 110 -41 32 33 3 32 10 56 33 1 37 31 42 27 137 0 0 32 4 48 12 44 23 10 111 -42 32 15 53 31 53 44 32 44 31 31 25 11 138 0 0 31 47 13 12 44 20 11 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5 37 26 - 4 45 46 - 6 6 29 -137 0 0 - 5 49 56 12 29 17 77 243 -41 - 5 38 41 - 6 1 11 - 5 9 36 - 6 30 10 -136 0 0 - 6 13 22 12 29 3 76 246 -40 - 6 2 8 - 6 24 36 - 5 33 7 - 6 53 32 -135 0 0 - 6 36 27 12 28 49 75 248 -39 - 6 25 15 - 6 47 40 - 5 56 17 - 7 16 33 -134 0 0 - 6 59 12 12 28 35 74 251 -38 - 6 48 1 - 7 10 23 - 6 19 6 - 7 39 13 -133 0 0 - 7 21 36 12 28 21 74 253 -37 - 7 10 26 - 7 32 46 - 6 41 35 - 8 1 32 -132 0 0 - 7 43 39 12 28 7 73 255 -36 - 7 32 30 - 7 54 47 - 7 3 42 - 8 23 30 -131 0 0 - 8 5 19 12 27 54 72 257 -35 - 7 54 12 - 8 16 27 - 7 25 27 - 8 45 6 -130 0 0 - 8 26 39 12 27 40 71 258 -34 - 8 15 32 - 8 37 44 - 7 46 51 - 9 6 21 -129 0 0 - 8 47 35 12 27 26 70 259 -33 - 8 36 30 - 8 58 40 - 8 7 52 - 9 27 13 -128 0 0 - 9 8 10 12 27 13 69 261 -32 - 8 57 6 - 9 19 13 - 8 28 32 - 9 47 43 -127 0 0 - 9 28 22 12 27 0 69 262 -32 - 9 17 19 - 9 39 24 - 8 48 48 -10 7 51 -126 0 0 - 9 48 11 12 26 46 68 263 -31 - 9 37 10 - 9 59 12 - 9 8 42 -10 27 35 -125 0 0 -10 7 37 12 26 33 67 264 -30 - 9 56 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-13 33 13 -13 54 43 -13 5 26 -14 22 25 -111 0 0 -13 57 44 12 23 44 54 269 -17 -13 47 0 -14 8 28 -13 19 16 -14 36 8 -110 0 0 -14 11 5 12 23 33 53 269 -16 -14 0 22 -14 21 48 -13 32 40 -14 49 25 -109 0 0 -14 24 0 12 23 22 52 269 -15 -14 13 18 -14 34 42 -13 45 39 -15 2 17 -108 0 0 -14 36 31 12 23 11 51 269 -14 -14 25 49 -14 47 12 -13 58 13 -15 14 44 -107 0 0 -14 48 35 12 23 0 50 269 -13 -14 37 55 -14 59 15 -14 10 20 -15 26 45 -106 0 0 -15 0 14 12 22 50 49 269 -12 -14 49 35 -15 10 53 -14 22 3 -15 38 21 -105 0 0 -15 11 28 12 22 40 49 269 -11 -15 0 49 -15 22 6 -14 33 19 -15 49 32 -104 0 0 -15 22 15 12 22 30 48 269 -10 -15 11 37 -15 32 53 -14 44 10 -16 0 16 -103 0 0 -15 32 37 12 22 20 47 269 -9 -15 22 0 -15 43 14 -14 54 35 -16 10 35 -102 0 0 -15 42 33 12 22 10 46 269 -8 -15 31 57 -15 53 9 -15 4 33 -16 20 29 -101 0 0 -15 52 4 12 22 0 45 269 -7 -15 41 28 -16 2 39 -15 14 6 -16 29 56 -100 0 0 -16 1 8 12 21 51 44 269 -7 -15 50 33 -16 11 42 -15 23 13 -16 38 58 - 99 0 0 -16 9 46 12 21 42 43 269 -6 -15 59 12 -16 20 20 -15 31 54 -16 47 34 - 98 0 0 -16 17 58 12 21 33 42 269 -5 -16 7 24 -16 28 31 -15 40 8 -16 55 44 - 97 0 0 -16 25 44 12 21 24 41 269 -4 -16 15 11 -16 36 17 -15 47 56 -17 3 28 - 96 0 0 -16 33 4 12 21 15 40 268 -3 -16 22 31 -16 43 36 -15 55 18 -17 10 45 - 95 0 0 -16 39 57 12 21 6 39 268 -2 -16 29 26 -16 50 29 -16 2 13 -17 17 37 - 94 0 0 -16 46 25 12 20 58 38 268 -1 -16 35 53 -16 56 56 -16 8 43 -17 24 2 - 93 0 0 -16 52 26 12 20 50 37 268 0 -16 41 55 -17 2 56 -16 14 45 -17 30 2 Uncertainty in time = +/- 7 secs [Prediction of 2008 Mar 28.0] Data for the target star ------------------------ * name: TYC 5589-00155-1 * constellation : Libra * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 15 12 56.5481 DE: -11 43 57.485 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .021, .022 ) * V mag [mag]: 10.2 * B mag [mag]: 11.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (877) Walkure approx. diameter [km]: 38 approx. diameter ["]: .026 distance from Earth [AU]: 2.02500 * orbital information: orbit source: Preston date of fit: 2008 Mar 27 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 987 number of rejected observations: 62 time covered by the observations: 1921 Feb 25 - 2008 Feb 12 1 sigma uncertainty ellipse (major, minor, PA): 0.030, 0.025, 109° remarks: * orbital elements for (877) Walkure : Mean anomaly = 186.15368634 deg Arg. of pericenter = 275.98368741 deg Long. of node = 116.43628456 deg Inclination = 4.25678073 deg Eccentricity = 0.16058466 Semimajor axis = 2.48577853 AU Perihelion dist = 2.08660062 AU Mag: H = 10.75, G = 0.15 Epoch of elements : MJD 54557.52200000 TDT (2008 Apr 01.522) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 Apr 1 877 Walkure 12h 31.3m UT 10.2 15 12 56.548-11 43 57.48TYC 5589-00155-1 11.0 15.3 38 4.9 2.025 -1.186 8.24 -149.8246 -11.735 -6.88 4.81 12.5213 0.07770 0.16225 -4.00553 1.89526 -0.00351 0.00047 2000 184.2620232008 325.00000275.983687116.436285 4.2567810.16058466 2.4857785 2.086600610.7 5.00.15 RATE 2.5148400 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.037 0.033 103 2.29 0.033 0 54553.5020080401_0155-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 28, 06:18 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org