IOTA/IOTA-ES occultation update for (1031) Arctica / UCAC2 31858915 event on 2012 Oct 31, 08:02 UT Visible from N Canada Summary ------- On 2012 Oct 31 UT, the 77 km diameter asteroid (1031) Arctica will occult a 11.9 mag star in the constellation Hydra for observers along a path across N Canada. In the case of an occultation, the combined light of the asteroid and the star will drop by 3.4 mag to 15.2 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: 29 * date and approx. time of event: 2012 Oct 31, 07:58 - 2012 Oct 31, 08:01 UT * geocentric midpoint of event [JD]: 2456231.8353375 * magnitude of target star: 11.9 * magnitude drop [mag]: 3.4 * estimated maximum duration [s]: 3.7 * Moon: 98 % sunlit, 80° distance * Sun: 85° distance * rough path description: N Canada The occultation path -------------------- * approximate projected width [km]: 93 * 1 sigma uncertainty interval [path widths]: +/- 2.32 * 1 sigma uncertainty interval [seconds]: +/- 8.4 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .086 +/- .086) * 1 sigma uncertainty ellipse (major, minor, PA): ( .086", .086", 0° ) * approx speed of asteroid's shadow [km/s]: 20.9737 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 31858915 by 1031 Arctica on 2012 Oct 31 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 -101 48 40 74 0 0 7 58 44 5 106 -29 -110 48 0 - 96 5 41 ... .. .. - 78 45 55 - 90 37 55 73 0 0 7 58 46 8 117 -28 - 94 47 20 - 86 58 39 ... .. .. - 73 22 52 Latitude Latitude Latitude Latitude - 90 0 0 72 55 32 7 58 47 8 118 -28 72 28 33 73 22 41 70 25 17 75 30 48 - 89 0 0 72 48 13 7 58 47 8 119 -28 72 21 5 73 15 30 70 17 11 75 24 20 - 88 0 0 72 40 34 7 58 47 9 120 -28 72 13 17 73 8 0 70 8 44 75 17 35 - 87 0 0 72 32 35 7 58 48 9 121 -28 72 5 10 73 0 11 69 59 56 75 10 32 - 86 0 0 72 24 16 7 58 48 9 121 -28 71 56 41 72 52 2 69 50 45 75 3 10 - 85 0 0 72 15 37 7 58 48 10 122 -28 71 47 52 72 43 32 69 41 12 74 55 30 - 84 0 0 72 6 36 7 58 49 10 123 -28 71 38 40 72 34 41 69 31 16 74 47 30 - 83 0 0 71 57 13 7 58 49 10 124 -27 71 29 7 72 25 29 69 20 56 74 39 10 - 82 0 0 71 47 27 7 58 49 11 125 -27 71 19 10 72 15 55 69 10 11 74 30 30 - 81 0 0 71 37 18 7 58 50 11 126 -27 71 8 50 72 5 57 68 59 2 74 21 29 - 80 0 0 71 26 46 7 58 50 12 127 -27 70 58 6 71 55 37 68 47 27 74 12 6 - 79 0 0 71 15 49 7 58 51 12 128 -27 70 46 57 71 44 52 68 35 26 74 2 21 - 78 0 0 71 4 26 7 58 51 12 129 -27 70 35 23 71 33 42 68 22 57 73 52 12 - 77 0 0 70 52 38 7 58 52 13 130 -27 70 23 22 71 22 6 68 10 2 73 41 40 - 76 0 0 70 40 23 7 58 52 13 131 -27 70 10 54 71 10 5 67 56 37 73 30 43 - 75 0 0 70 27 41 7 58 53 13 132 -26 69 57 59 70 57 36 67 42 43 73 19 21 - 74 0 0 70 14 30 7 58 54 14 133 -26 69 44 35 70 44 39 67 28 20 73 7 32 - 73 0 0 70 0 50 7 58 54 14 134 -26 69 30 41 70 31 13 67 13 25 72 55 16 - 72 0 0 69 46 40 7 58 55 15 135 -26 69 16 16 70 17 17 66 57 59 72 42 33 - 71 0 0 69 31 59 7 58 56 15 136 -26 69 1 21 70 2 51 66 42 0 72 29 20 - 70 0 0 69 16 46 7 58 56 15 137 -26 68 45 53 69 47 53 66 25 27 72 15 37 - 69 0 0 69 1 0 7 58 57 16 138 -25 68 29 52 69 32 23 66 8 20 72 1 23 - 68 0 0 68 44 40 7 58 58 16 139 -25 68 13 16 69 16 18 65 50 37 71 46 37 - 67 0 0 68 27 45 7 58 59 17 140 -25 67 56 6 68 59 39 65 32 18 71 31 18 - 66 0 0 68 10 14 7 59 0 17 141 -25 67 38 19 68 42 25 65 13 21 71 15 25 - 65 0 0 67 52 5 7 59 1 18 142 -25 67 19 54 68 24 33 64 53 46 70 58 56 - 64 0 0 67 33 19 7 59 2 18 143 -24 67 0 51 68 6 3 64 33 31 70 41 51 - 63 0 0 67 13 52 7 59 3 19 144 -24 66 41 8 67 46 54 64 12 35 70 24 7 - 62 0 0 66 53 45 7 59 4 19 145 -24 66 20 44 67 27 4 63 50 57 70 5 44 - 61 0 0 66 32 56 7 59 5 20 145 -24 65 59 38 67 6 33 63 28 37 69 46 41 - 60 0 0 66 11 24 7 59 6 20 146 -23 65 37 48 66 45 18 63 5 32 69 26 56 - 59 0 0 65 49 7 7 59 7 21 147 -23 65 15 14 66 23 19 62 41 42 69 6 27 - 58 0 0 65 26 5 7 59 9 21 148 -23 64 51 54 66 0 35 62 17 6 68 45 13 - 57 0 0 65 2 15 7 59 10 22 149 -23 64 27 46 65 37 3 61 51 43 68 23 13 - 56 0 0 64 37 37 7 59 11 22 150 -22 64 2 51 65 12 44 61 25 30 68 0 25 - 55 0 0 64 12 9 7 59 13 23 151 -22 63 37 5 64 47 34 60 58 28 67 36 48 - 54 0 0 63 45 51 7 59 14 24 152 -22 63 10 29 64 21 34 60 30 35 67 12 20 - 53 0 0 63 18 40 7 59 16 24 153 -21 62 43 0 63 54 41 60 1 50 66 47 0 - 52 0 0 62 50 35 7 59 18 25 154 -21 62 14 38 63 26 54 59 32 12 66 20 46 - 51 0 0 62 21 36 7 59 20 26 155 -20 61 45 21 62 58 13 59 1 40 65 53 36 - 50 0 0 61 51 40 7 59 22 26 156 -20 61 15 8 62 28 35 58 30 13 65 25 29 - 49 0 0 61 20 47 7 59 24 27 157 -20 60 43 58 61 58 0 57 57 49 64 56 24 - 48 0 0 60 48 56 7 59 26 28 158 -19 60 11 50 61 26 27 57 24 29 64 26 19 - 47 0 0 60 16 6 7 59 28 28 159 -19 59 38 43 60 53 53 56 50 11 63 55 13 - 46 0 0 59 42 14 7 59 30 29 160 -18 59 4 35 60 20 18 56 14 55 63 23 4 - 45 0 0 59 7 22 7 59 33 30 161 -18 58 29 27 59 45 42 55 38 39 62 49 50 - 44 0 0 58 31 27 7 59 35 30 162 -17 57 53 17 59 10 3 55 1 24 62 15 32 - 43 0 0 57 54 29 7 59 38 31 164 -17 57 16 4 58 33 20 54 23 9 61 40 8 - 42 0 0 57 16 28 7 59 41 32 165 -16 56 37 49 57 55 34 53 43 53 61 3 36 - 41 0 0 56 37 22 7 59 44 33 166 -16 55 58 30 57 16 42 53 3 37 60 25 56 - 40 0 0 55 57 12 7 59 47 33 167 -15 55 18 7 56 36 45 52 22 20 59 47 7 - 39 0 0 55 15 58 7 59 50 34 168 -14 54 36 41 55 55 43 51 40 3 59 7 8 - 38 0 0 54 33 39 7 59 53 35 169 -14 53 54 11 55 13 36 50 56 46 58 26 0 - 37 0 0 53 50 16 7 59 57 36 170 -13 53 10 38 54 30 23 50 12 29 57 43 43 - 36 0 0 53 5 49 8 0 0 37 171 -12 52 26 1 53 46 6 49 27 13 57 0 15 - 35 0 0 52 20 18 8 0 4 38 173 -12 51 40 23 53 0 44 48 40 59 56 15 37 - 34 0 0 51 33 46 8 0 8 38 174 -11 50 53 42 52 14 19 47 53 47 55 29 51 - 33 0 0 50 46 11 8 0 12 39 175 -10 50 6 2 51 26 51 47 5 40 54 42 57 - 32 0 0 49 57 37 8 0 16 40 176 -9 49 17 22 50 38 22 46 16 39 53 54 55 - 31 0 0 49 8 4 8 0 21 41 178 -9 48 27 45 49 48 53 45 26 45 53 5 47 - 30 0 0 48 17 34 8 0 25 42 179 -8 47 37 12 48 58 26 44 36 0 52 15 35 - 29 0 0 47 26 9 8 0 30 43 180 -7 46 45 46 48 7 3 43 44 26 51 24 21 - 28 0 0 46 33 51 8 0 35 44 182 -6 45 53 28 47 14 46 42 52 6 50 32 6 - 27 0 0 45 40 43 8 0 40 44 183 -5 45 0 21 46 21 37 41 59 1 49 38 53 - 26 0 0 44 46 48 8 0 45 45 185 -4 44 6 27 45 27 40 41 5 15 48 44 46 - 25 0 0 43 52 8 8 0 51 46 186 -3 43 11 50 44 32 56 40 10 51 47 49 45 - 24 0 0 42 56 46 8 0 56 47 188 -2 42 16 32 43 37 30 39 15 51 46 53 56 - 23 0 0 42 0 45 8 1 2 48 189 -1 41 20 37 42 41 24 38 20 18 45 57 21 - 22 0 0 41 4 10 8 1 8 48 191 0 40 24 8 41 44 42 37 24 17 45 0 4 Uncertainty in time = +/- 8 secs Prediction of 2012 Jul 10.0 Data for the target star ------------------------ * name: UCAC2 31858915 * constellation : Hydra * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 08 43 05.3633 DE: +00 01 47.409 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .083, .085 ) * V mag [mag]: 11.9 * B mag [mag]: 0.0 * Apparent position with proper motion RA(deg): 130.9401379833 DE(deg): -0.0170947648 * Equation of equinoxes (radians) : 0.000057771021129 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (1031) Arctica approx. diameter [km]: 77 approx. diameter ["]: .037 distance from Earth [AU]: 2.84800 * orbital information: orbit source: Preston date of fit: 2012 Jul 10 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1078 number of rejected observations: 71 time covered by the observations: 1913 May 09 - 2012 Feb 23 1 sigma uncertainty ellipse (major, minor, PA): 0.022, 0.010, 104° remarks: * orbital elements for (1031) Arctica : Mean anomaly = 313.42523041 deg Arg. of pericenter = 305.87957005 deg Long. of node = 218.94720983 deg Inclination = 17.63574314 deg Eccentricity = 0.05637644 Semimajor axis = 3.04760142 AU Perihelion dist = 2.87578851 AU Mag: H = 9.48, G = 0.15 Epoch of elements : MJD 56231.33500000 TDT (2012 Oct 31.335) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 31 1031 Arctica 8h 2.9m UT 11.9 8 43 5.363 0 1 47.41UCAC2 31858915 0.0 15.2 77 3.7 2.848 1.864 -23.54 -29.9797 0.037 55.19 -14.27 8.0481 0.36220 0.43045 9.05751 -7.62250 -0.00565 0.00143 2000 313.17791620121030.00000305.879570218.947210 17.6357430.05637644 3.0476014 2.8757885 9.6 5.00.15 RATE 1.8525370 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.086 0.086 0 3.32 0.086 0 0 3-1 056118.0020121031_858915 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 03, 21:00 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org