IOTA/IOTA-ES occultation update for (375) Ursula / 2UCAC 12284669 event on 2008 May 13, 08:23 UT Visible from Colombia, Ecuador Summary ------- On 2008 May 13 UT, the 216 km diameter asteroid (375) Ursula will occult a 12.5 mag star in the constellation Ara for observers along a path across Colombia, Ecuador. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.5 mag to 12.0 mag (the magnitude of the asteroid) for at most 22.2 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: 99 * date and approx. time of event: 2008 May 13, 08:13 - 2008 May 13, 08:32 UT * magnitude of target star: 12.5 * magnitude drop [mag]: 0.5 * estimated maximum duration [s]: 22.2 * Moon: 62 % sunlit, 101° distance * Sun: 146° distance * rough path description: Colombia, Ecuador The occultation path -------------------- * approximate projected width [km]: 255 * 1 sigma uncertainty interval [path widths]: +/- 0.21 * 1 sigma uncertainty interval [seconds]: +/- 3.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .029) * 1 sigma uncertainty ellipse (major, minor, PA): ( .032", .029", 91° ) * approx speed of asteroid's shadow [km/s]: 9.7277 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 12284669 by 375 Ursula on 2008 May 13 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 176 0 0 9 14 53 8 32 30 1 137 -29 .. .. .. 7 34 27 .. .. .. 6 53 3 177 0 0 8 13 18 8 32 29 2 137 -30 9 55 5 6 34 17 10 38 44 5 53 26 178 0 0 7 13 15 8 32 28 4 137 -32 8 53 33 5 35 35 9 36 33 4 55 18 179 0 0 6 14 43 8 32 27 5 137 -33 7 53 36 4 38 23 8 35 57 3 58 36 180 0 0 5 17 42 8 32 25 6 137 -34 6 55 13 3 42 38 7 36 57 3 3 22 -179 0 0 4 22 11 8 32 23 8 137 -36 5 58 22 2 48 21 6 39 31 2 9 35 -178 0 0 3 28 10 8 32 20 9 138 -37 5 3 4 1 55 31 5 43 39 1 17 13 -177 0 0 2 35 37 8 32 17 10 138 -38 4 9 17 1 4 6 4 49 19 0 26 16 -176 0 0 1 44 30 8 32 14 12 138 -40 3 16 59 0 14 7 3 56 30 - 0 23 17 -175 0 0 0 54 50 8 32 10 13 138 -41 2 26 11 - 0 34 29 3 5 11 - 1 11 27 -174 0 0 0 6 35 8 32 6 14 138 -42 1 36 50 - 1 21 42 2 15 21 - 1 58 15 -173 0 0 - 0 40 16 8 32 2 15 138 -43 0 48 55 - 2 7 34 1 26 59 - 2 43 43 -172 0 0 - 1 25 44 8 31 57 17 138 -44 0 2 25 - 2 52 5 0 40 2 - 3 27 51 -171 0 0 - 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9 59 12 -13 29 38 -100 0 0 -11 22 16 8 20 59 55 182 -64 -10 7 13 -12 36 13 - 9 35 21 -13 6 59 - 99 0 0 -10 58 3 8 20 48 55 184 -63 - 9 42 33 -12 12 27 - 9 10 29 -12 43 23 - 98 0 0 -10 32 51 8 20 36 54 185 -62 - 9 16 52 -11 47 42 - 8 44 35 -12 18 49 - 97 0 0 -10 6 38 8 20 25 54 186 -61 - 8 50 9 -11 21 57 - 8 17 40 -11 53 16 - 96 0 0 - 9 39 24 8 20 14 53 187 -60 - 8 22 24 -10 55 13 - 7 49 41 -11 26 44 - 95 0 0 - 9 11 8 8 20 2 53 188 -59 - 7 53 36 -10 27 28 - 7 20 39 -10 59 11 - 94 0 0 - 8 41 49 8 19 51 52 189 -58 - 7 23 43 - 9 58 42 - 6 50 31 -10 30 38 - 93 0 0 - 8 11 27 8 19 40 52 190 -56 - 6 52 46 - 9 28 53 - 6 19 18 -10 1 3 - 92 0 0 - 7 40 0 8 19 28 51 191 -55 - 6 20 42 - 8 58 1 - 5 46 59 - 9 30 25 - 91 0 0 - 7 7 27 8 19 17 50 192 -54 - 5 47 31 - 8 26 4 - 5 13 31 - 8 58 43 - 90 0 0 - 6 33 48 8 19 6 49 192 -53 - 5 13 12 - 7 53 3 - 4 38 55 - 8 25 57 - 89 0 0 - 5 59 2 8 18 54 49 193 -52 - 4 37 45 - 7 18 56 - 4 3 9 - 7 52 6 - 88 0 0 - 5 23 7 8 18 43 48 194 -51 - 4 1 7 - 6 43 42 - 3 26 13 - 7 17 8 - 87 0 0 - 4 46 3 8 18 32 47 195 -50 - 3 23 18 - 6 7 20 - 2 48 5 - 6 41 3 - 86 0 0 - 4 7 49 8 18 21 46 195 -49 - 2 44 18 - 5 29 49 - 2 8 44 - 6 3 50 - 85 0 0 - 3 28 23 8 18 10 45 196 -48 - 2 4 4 - 4 51 9 - 1 28 9 - 5 25 28 - 84 0 0 - 2 47 46 8 17 59 44 197 -47 - 1 22 36 - 4 11 18 - 0 46 20 - 4 45 57 - 83 0 0 - 2 5 54 8 17 48 43 197 -45 - 0 39 54 - 3 30 16 - 0 3 14 - 4 5 14 - 82 0 0 - 1 22 49 8 17 37 42 198 -44 0 4 5 - 2 48 1 0 41 8 - 3 23 19 - 81 0 0 - 0 38 29 8 17 26 41 199 -43 0 49 21 - 2 4 33 1 26 49 - 2 40 12 - 80 0 0 0 7 8 8 17 15 40 199 -42 1 35 56 - 1 19 50 2 13 49 - 1 55 52 - 79 0 0 0 54 1 8 17 4 39 200 -41 2 23 49 - 0 33 53 3 2 9 - 1 10 17 - 78 0 0 1 42 13 8 16 54 38 200 -39 3 13 3 0 13 21 3 51 50 - 0 23 27 - 77 0 0 2 31 43 8 16 43 37 201 -38 4 3 38 1 1 51 4 42 53 0 24 39 - 76 0 0 3 22 33 8 16 33 36 201 -37 4 55 34 1 51 39 5 35 19 1 14 2 - 75 0 0 4 14 44 8 16 23 35 202 -36 5 48 54 2 42 45 6 29 9 2 4 43 - 74 0 0 5 8 15 8 16 13 34 202 -35 6 43 36 3 35 9 7 24 24 2 56 41 - 73 0 0 6 3 8 8 16 3 33 203 -33 7 39 44 4 28 54 8 21 4 3 49 58 - 72 0 0 6 59 23 8 15 54 31 203 -32 8 37 15 5 23 58 9 19 10 4 44 34 - 71 0 0 7 57 1 8 15 45 30 203 -31 9 36 13 6 20 23 10 18 42 5 40 29 - 70 0 0 8 56 2 8 15 36 29 204 -29 10 36 35 7 18 8 11 19 42 6 37 44 - 69 0 0 9 56 26 8 15 27 27 204 -28 11 38 24 8 17 14 12 22 8 7 36 19 - 68 0 0 10 58 13 8 15 18 26 205 -27 12 41 39 9 17 40 13 26 2 8 36 14 - 67 0 0 12 1 23 8 15 10 25 205 -25 13 46 20 10 19 27 14 31 24 9 37 28 - 66 0 0 13 5 56 8 15 2 23 205 -24 14 52 26 11 22 35 15 38 12 10 40 2 - 65 0 0 14 11 51 8 14 55 22 206 -23 15 59 57 12 27 2 16 46 27 11 43 54 - 64 0 0 15 19 7 8 14 48 21 206 -21 17 8 53 13 32 48 17 56 8 12 49 4 - 63 0 0 16 27 44 8 14 41 19 207 -20 18 19 12 14 39 52 19 7 13 13 55 31 - 62 0 0 17 37 40 8 14 35 18 207 -19 19 30 53 15 48 12 20 19 42 15 3 15 - 61 0 0 18 48 53 8 14 29 16 207 -17 20 43 54 16 57 48 21 33 32 16 12 12 - 60 0 0 20 1 21 8 14 23 15 208 -16 21 58 14 18 8 37 22 48 42 17 22 22 - 59 0 0 21 15 3 8 14 19 13 208 -15 23 13 49 19 20 36 24 5 9 18 33 42 - 58 0 0 22 29 55 8 14 14 12 209 -13 24 30 37 20 33 44 25 22 50 19 46 9 - 57 0 0 23 45 54 8 14 10 10 209 -12 25 48 35 21 47 58 26 41 42 20 59 42 - 56 0 0 25 2 57 8 14 7 9 209 -11 27 7 38 23 3 13 28 1 40 22 14 15 - 55 0 0 26 20 59 8 14 4 7 210 -9 28 27 42 24 19 27 29 22 41 23 29 47 - 54 0 0 27 39 55 8 14 2 5 210 -8 29 48 42 25 36 34 30 44 38 24 46 12 - 53 0 0 28 59 41 8 14 0 4 211 -6 31 10 33 26 54 30 32 7 27 26 3 25 - 52 0 0 30 20 11 8 13 59 2 211 -5 32 33 8 28 13 10 .. .. .. 27 21 23 - 51 0 0 31 41 19 8 13 58 1 212 -4 .. .. .. 29 32 28 .. .. .. 28 39 58 Uncertainty in time = +/- 5 secs [Prediction of 2008 May 8.0] Data for the target star ------------------------ * name: 2UCAC 12284669 * constellation : Ara * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 16 58 10.3039 DE: -45 50 34.979 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .022, .027 ) * V mag [mag]: 12.5 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (375) Ursula approx. diameter [km]: 216 approx. diameter ["]: .142 distance from Earth [AU]: 2.09300 * orbital information: orbit source: Preston date of fit: 2008 May 07 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 655 number of rejected observations: 82 time covered by the observations: 1904 Sep 19 - 2008 Apr 25 1 sigma uncertainty ellipse (major, minor, PA): 0.023, 0.011, 92° remarks: * orbital elements for (375) Ursula : Mean anomaly = 300.03068284 deg Arg. of pericenter = 344.25719598 deg Long. of node = 336.65213463 deg Inclination = 15.93252792 deg Eccentricity = 0.10802401 Semimajor axis = 3.12476574 AU Perihelion dist = 2.78721602 AU Mag: H = 7.49, G = 0.27 Epoch of elements : MJD 54599.35000000 TDT (2008 May 13.350) ------ occelmnt file for Occult BEGIN ----------------------------------- 2008 May 13 375 Ursula 8h 23.2m UT 12.5 16 58 10.304-45 50 34.982UCAC 12284669 0.0 12.0 216 22.2 2.093 -2.104 -7.04 -102.7314 -45.841 53.28 18.51 8.3871 -0.16122 0.50407 -5.22842 -1.67643 -0.00216 0.00227 2000 298.3623242008 5 4.00000344.257196336.652135 15.9325280.10802401 3.1247657 2.7872160 7.5 5.00.27 RATE 1.7843410 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.032 0.029 91 1.21 0.030 0 54594.5020080513_284669 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 May 08, 03:10 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org