IOTA/IOTA-ES occultation update for (987) Wallia / TYC 2436-00331-1 event on 2012 Oct 02, 16:26 UT Visible from Philippines Summary ------- On 2012 Oct 02 UT, the 52 km diameter asteroid (987) Wallia will occult a 12.9 mag star in the constellation Gemini for observers along a path across Philippines. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.3 mag to 15.1 mag (the magnitude of the asteroid) for at most 3.7 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 55 * date and approx. time of event: 2012 Oct 02, 16:18 - 2012 Oct 02, 16:26 UT * geocentric midpoint of event [JD]: 2456203.18481667 * magnitude of target star: 12.9 * magnitude drop [mag]: 2.3 * estimated maximum duration [s]: 3.7 * Moon: 94 % sunlit, 62° distance * Sun: 90° distance * rough path description: Philippines The occultation path -------------------- * approximate projected width [km]: 52 * 1 sigma uncertainty interval [path widths]: +/- 1.15 * 1 sigma uncertainty interval [seconds]: +/- 4.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .034 +/- .028) * 1 sigma uncertainty ellipse (major, minor, PA): ( .034", .027", 94° ) * approx speed of asteroid's shadow [km/s]: 13.9600 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 2436-00331-1 by 987 Wallia on 2012 Oct 2 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 117 0 0 - 1 49 10 16 18 32 1 59 -83 - 2 5 44 - 1 32 36 - 2 43 48 - 0 54 28 118 0 0 - 1 12 12 16 18 33 2 59 -83 - 1 28 46 - 0 55 37 - 2 6 53 - 0 17 26 119 0 0 - 0 35 5 16 18 33 3 59 -82 - 0 51 41 - 0 18 29 - 1 29 50 0 19 44 120 0 0 0 2 9 16 18 34 4 59 -82 - 0 14 27 0 18 46 - 0 52 38 0 57 1 121 0 0 0 39 30 16 18 34 5 59 -81 0 22 53 0 56 8 - 0 15 20 1 34 24 122 0 0 1 16 56 16 18 35 7 59 -80 1 0 18 1 33 34 0 22 4 2 11 51 123 0 0 1 54 25 16 18 37 8 59 -79 1 37 47 2 11 4 0 59 32 2 49 22 124 0 0 2 31 58 16 18 38 9 59 -79 2 15 19 2 48 37 1 37 3 3 26 56 125 0 0 3 9 31 16 18 39 10 59 -78 2 52 52 3 26 11 2 14 36 4 4 31 126 0 0 3 47 5 16 18 41 11 59 -77 3 30 26 4 3 45 2 52 9 4 42 5 127 0 0 4 24 38 16 18 43 12 59 -76 4 7 59 4 41 17 3 29 42 5 19 38 128 0 0 5 2 9 16 18 45 14 59 -75 4 45 30 5 18 48 4 7 13 5 57 8 129 0 0 5 39 36 16 18 48 15 59 -74 5 22 57 5 56 15 4 44 41 6 34 34 130 0 0 6 16 58 16 18 50 16 59 -72 6 0 19 6 33 36 5 22 4 7 11 55 131 0 0 6 54 14 16 18 53 17 59 -71 6 37 36 7 10 52 5 59 22 7 49 9 132 0 0 7 31 23 16 18 56 18 59 -70 7 14 46 7 48 0 6 36 33 8 26 16 133 0 0 8 8 23 16 18 59 20 60 -69 7 51 47 8 25 0 7 13 36 9 3 14 134 0 0 8 45 14 16 19 2 21 60 -68 8 28 38 9 1 50 7 50 30 9 40 2 135 0 0 9 21 54 16 19 5 22 60 -67 9 5 19 9 38 29 8 27 13 10 16 38 136 0 0 9 58 21 16 19 9 23 60 -66 9 41 48 10 14 55 9 3 44 10 53 2 137 0 0 10 34 36 16 19 13 24 60 -65 10 18 4 10 51 9 9 40 3 11 29 13 138 0 0 11 10 36 16 19 17 25 60 -64 10 54 5 11 27 7 10 16 7 12 5 9 139 0 0 11 46 21 16 19 21 27 61 -63 11 29 52 12 2 51 10 51 57 12 40 49 140 0 0 12 21 49 16 19 25 28 61 -61 12 5 21 12 38 18 11 27 30 13 16 12 141 0 0 12 57 0 16 19 29 29 61 -60 12 40 34 13 13 27 12 2 47 13 51 17 142 0 0 13 31 52 16 19 34 30 61 -59 13 15 28 13 48 17 12 37 45 14 26 3 143 0 0 14 6 25 16 19 38 31 62 -58 13 50 3 14 22 48 13 12 24 15 0 30 144 0 0 14 40 38 16 19 43 32 62 -57 14 24 17 14 56 59 13 46 42 15 34 36 145 0 0 15 14 29 16 19 48 33 62 -56 14 58 10 15 30 48 14 20 40 16 8 20 146 0 0 15 47 58 16 19 53 35 62 -55 15 31 41 16 4 14 14 54 16 16 41 42 147 0 0 16 21 3 16 19 58 36 63 -54 16 4 49 16 37 18 15 27 29 17 14 40 148 0 0 16 53 45 16 20 4 37 63 -53 16 37 33 17 9 58 16 0 19 17 47 15 149 0 0 17 26 3 16 20 9 38 63 -52 17 9 53 17 42 13 16 32 44 18 19 25 150 0 0 17 57 55 16 20 15 39 64 -50 17 41 48 18 14 3 17 4 44 18 51 9 151 0 0 18 29 21 16 20 20 40 64 -49 18 13 17 18 45 26 17 36 19 19 22 27 152 0 0 19 0 21 16 20 26 41 64 -48 18 44 19 19 16 24 18 7 27 19 53 18 153 0 0 19 30 54 16 20 32 42 65 -47 19 14 54 19 46 54 18 38 8 20 23 42 154 0 0 20 0 59 16 20 38 43 65 -46 19 45 2 20 16 56 19 8 22 20 53 38 155 0 0 20 30 35 16 20 44 44 66 -45 20 14 41 20 46 30 19 38 7 21 23 6 156 0 0 20 59 43 16 20 50 46 66 -44 20 43 52 21 15 35 20 7 24 21 52 5 157 0 0 21 28 22 16 20 56 47 66 -43 21 12 33 21 44 11 20 36 12 22 20 34 158 0 0 21 56 31 16 21 2 48 67 -42 21 40 45 22 12 17 21 4 31 22 48 34 159 0 0 22 24 11 16 21 8 49 67 -41 22 8 28 22 39 54 21 32 19 23 16 4 160 0 0 22 51 20 16 21 15 50 68 -40 22 35 40 23 7 0 21 59 38 23 43 4 161 0 0 23 17 58 16 21 21 51 68 -39 23 2 21 23 33 36 22 26 26 24 9 33 162 0 0 23 44 6 16 21 28 52 69 -38 23 28 32 23 59 41 22 52 43 24 35 32 163 0 0 24 9 43 16 21 34 53 69 -37 23 54 11 24 25 15 23 18 29 25 0 59 164 0 0 24 34 48 16 21 41 54 70 -36 24 19 19 24 50 17 23 43 44 25 25 55 165 0 0 24 59 22 16 21 47 55 70 -35 24 43 56 25 14 48 24 8 27 25 50 19 166 0 0 25 23 24 16 21 54 56 71 -34 25 8 1 25 38 48 24 32 39 26 14 12 167 0 0 25 46 55 16 22 1 57 71 -33 25 31 35 26 2 15 24 56 19 26 37 33 168 0 0 26 9 54 16 22 7 58 72 -32 25 54 36 26 25 11 25 19 27 27 0 22 169 0 0 26 32 21 16 22 14 59 72 -31 26 17 6 26 47 35 25 42 3 27 22 40 170 0 0 26 54 15 16 22 21 60 73 -30 26 39 4 27 9 27 26 4 7 27 44 25 171 0 0 27 15 38 16 22 28 61 74 -29 27 0 29 27 30 47 26 25 39 28 5 39 172 0 0 27 36 29 16 22 35 62 74 -28 27 21 22 27 51 35 26 46 39 28 26 21 173 0 0 27 56 47 16 22 41 63 75 -27 27 41 44 28 11 51 27 7 6 28 46 30 174 0 0 28 16 34 16 22 48 64 76 -26 28 1 33 28 31 35 27 27 1 29 6 8 175 0 0 28 35 48 16 22 55 65 76 -25 28 20 50 28 50 47 27 46 25 29 25 14 176 0 0 28 54 31 16 23 2 66 77 -24 28 39 35 29 9 26 28 5 16 29 43 47 177 0 0 29 12 41 16 23 9 67 78 -23 28 57 48 29 27 34 28 23 35 30 1 50 178 0 0 29 30 20 16 23 16 68 78 -22 29 15 29 29 45 10 28 41 21 30 19 20 179 0 0 29 47 26 16 23 23 68 79 -21 29 32 38 30 2 15 28 58 36 30 36 18 180 0 0 30 4 1 16 23 30 69 80 -20 29 49 16 30 18 47 29 15 19 30 52 45 -179 0 0 30 20 5 16 23 37 70 81 -20 30 5 21 30 34 48 29 31 30 31 8 41 -178 0 0 30 35 36 16 23 44 71 82 -19 30 20 55 30 50 18 29 47 9 31 24 5 -177 0 0 30 50 37 16 23 51 72 83 -18 30 35 58 31 5 16 30 2 17 31 38 58 -176 0 0 31 5 6 16 23 58 73 83 -17 30 50 29 31 19 42 30 16 53 31 53 20 -175 0 0 31 19 3 16 24 5 74 84 -16 31 4 29 31 33 38 30 30 58 32 7 10 -174 0 0 31 32 30 16 24 12 75 86 -15 31 17 57 31 47 2 30 44 31 32 20 30 -173 0 0 31 45 25 16 24 19 76 87 -14 31 30 55 31 59 56 30 57 33 32 33 19 -172 0 0 31 57 50 16 24 26 76 88 -13 31 43 21 32 12 18 31 10 4 32 45 37 -171 0 0 32 9 43 16 24 33 77 89 -12 31 55 17 32 24 10 31 22 4 32 57 25 -170 0 0 32 21 7 16 24 40 78 91 -11 32 6 42 32 35 32 31 33 33 33 8 42 -169 0 0 32 31 59 16 24 47 79 92 -11 32 17 36 32 46 22 31 44 31 33 19 29 -168 0 0 32 42 21 16 24 54 80 94 -10 32 27 59 32 56 43 31 54 58 33 29 45 -167 0 0 32 52 13 16 25 1 81 96 -9 32 37 53 33 6 33 32 4 55 33 39 32 -166 0 0 33 1 34 16 25 7 81 98 -8 32 47 16 33 15 53 32 14 22 33 48 48 -165 0 0 33 10 26 16 25 14 82 101 -7 32 56 8 33 24 43 32 23 18 33 57 35 -164 0 0 33 18 47 16 25 21 83 104 -6 33 4 31 33 33 3 32 31 44 34 5 52 -163 0 0 33 26 38 16 25 28 84 108 -5 33 12 24 33 40 53 32 39 39 34 13 39 -162 0 0 33 34 0 16 25 35 84 113 -5 33 19 47 33 48 13 32 47 5 34 20 57 -161 0 0 33 40 52 16 25 42 85 120 -4 33 26 40 33 55 4 32 54 0 34 27 45 -160 0 0 33 47 14 16 25 49 86 129 -3 33 33 3 34 1 25 33 0 26 34 34 4 -159 0 0 33 53 7 16 25 56 86 141 -2 33 38 57 34 7 17 33 6 22 34 39 53 -158 0 0 33 58 30 16 26 3 86 157 -1 33 44 21 34 12 40 33 11 48 34 45 14 -157 0 0 34 3 24 16 26 9 86 177 0 33 49 16 34 17 33 33 16 45 34 50 5 Uncertainty in time = +/- 5 secs Prediction of 2012 Jul 10.0 Data for the target star ------------------------ * name: TYC 2436-00331-1 * constellation : Gemini * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 06 45 09.2932 DE: +31 21 13.444 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .029, .025 ) * V mag [mag]: 12.9 * B mag [mag]: 12.5 * Apparent position with proper motion RA(deg): 101.4989202370 DE(deg): 31.3374221159 * Equation of equinoxes (radians) : 0.000062493006438 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (987) Wallia approx. diameter [km]: 52 approx. diameter ["]: .024 distance from Earth [AU]: 2.95500 * orbital information: orbit source: Preston date of fit: 2012 Jul 09 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1111 number of rejected observations: 57 time covered by the observations: 1937 May 01 - 2012 Feb 02 1 sigma uncertainty ellipse (major, minor, PA): 0.018, 0.012, 103° remarks: * orbital elements for (987) Wallia : Mean anomaly = 74.30569579 deg Arg. of pericenter = 16.70270925 deg Long. of node = 322.78158952 deg Inclination = 8.88385149 deg Eccentricity = 0.23204193 Semimajor axis = 3.14954530 AU Perihelion dist = 2.41871875 AU Mag: H = 9.46, G = 0.15 Epoch of elements : MJD 56202.68500000 TDT (2012 Oct 02.685) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 2 987 Wallia 16h 26.1m UT 12.9 6 45 9.293 31 21 13.44TYC 2436-00331-1 12.6 15.1 52 3.7 2.955 1.823 2.08 -157.0371 31.353 -69.24 -3.91 16.4356 -0.00512 0.04405 7.84841 0.69844 -0.00577 0.00046 2000 73.8322432012 930.00000 16.702709322.781590 8.8838510.23204193 3.1495453 2.4187187 9.3 5.00.15 RATE 1.7633250 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.034 0.027 94 2.15 0.028 0 0 2 4 056118.0020121002_0331-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Aug 06, 17:09 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org