IOTA/IOTA-ES occultation update for (138) Tolosa / TYC 6819-07252-1 event on 2012 Aug 20, 03:24 UT Visible from SE Canada, USA Summary ------- On 2012 Aug 20 UT, the 52 km diameter asteroid (138) Tolosa will occult a 12.0 mag star in the constellation Ophiuchus for observers along a path across SE Canada, USA. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.0 mag to 12.4 mag (the magnitude of the asteroid) for at most 6.0 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC. The event at a glimpse ---------------------- * Rank: 78 * date and approx. time of event: 2012 Aug 20, 03:22 - 2012 Aug 20, 03:30 UT * geocentric midpoint of event [JD]: 2456159.6419125 * magnitude of target star: 12.0 * magnitude drop [mag]: 1.0 * estimated maximum duration [s]: 6.0 * Moon: 7 % sunlit, 80° distance * Sun: 111° distance * rough path description: SE Canada, USA The occultation path -------------------- * approximate projected width [km]: 110 * 1 sigma uncertainty interval [path widths]: +/- 0.71 * 1 sigma uncertainty interval [seconds]: +/- 3.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .034) * 1 sigma uncertainty ellipse (major, minor, PA): ( .034", .032", 1° ) * approx speed of asteroid's shadow [km/s]: 8.6670 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6819-07252-1 by 138 Tolosa on 2012 Aug 20 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 Latitude Latitude Latitude Latitude -130 0 0 37 13 32 3 22 23 26 172 0 36 42 40 37 44 57 35 59 44 38 30 35 -129 0 0 37 0 48 3 22 33 26 173 -1 36 30 4 37 32 5 35 47 17 38 17 30 -128 0 0 36 48 57 3 22 43 27 174 -2 36 18 20 37 20 6 35 35 43 38 5 20 -127 0 0 36 38 0 3 22 54 27 175 -3 36 7 29 37 9 2 35 25 1 37 54 5 -126 0 0 36 27 56 3 23 5 27 176 -4 35 57 31 36 58 52 35 15 11 37 43 45 -125 0 0 36 18 45 3 23 16 27 177 -4 35 48 26 36 49 35 35 6 14 37 34 20 -124 0 0 36 10 29 3 23 26 28 178 -5 35 40 15 36 41 14 34 58 9 37 25 50 -123 0 0 36 3 6 3 23 37 28 180 -6 35 32 56 36 33 46 34 50 56 37 18 16 -122 0 0 35 56 36 3 23 48 28 181 -7 35 26 31 36 27 13 34 44 36 37 11 36 -121 0 0 35 51 1 3 23 59 28 182 -8 35 20 59 36 21 34 34 39 8 37 5 52 -120 0 0 35 46 19 3 24 10 28 183 -9 35 16 20 36 16 49 34 34 33 37 1 3 -119 0 0 35 42 32 3 24 21 28 184 -9 35 12 34 36 12 59 34 30 51 36 57 9 -118 0 0 35 39 38 3 24 32 28 185 -10 35 9 42 36 10 3 34 28 1 36 54 10 -117 0 0 35 37 37 3 24 43 28 186 -11 35 7 43 36 8 1 34 26 4 36 52 6 -116 0 0 35 36 31 3 24 54 28 187 -12 35 6 38 36 6 54 34 24 59 36 50 58 -115 0 0 35 36 18 3 25 5 28 188 -13 35 6 25 36 6 41 34 24 47 36 50 45 -114 0 0 35 36 59 3 25 15 28 189 -13 35 7 6 36 7 23 34 25 28 36 51 26 -113 0 0 35 38 34 3 25 26 27 190 -14 35 8 40 36 8 58 34 27 1 36 53 3 -112 0 0 35 41 3 3 25 37 27 191 -15 35 11 7 36 11 28 34 29 26 36 55 35 -111 0 0 35 44 25 3 25 47 27 192 -16 35 14 28 36 14 52 34 32 45 36 59 2 -110 0 0 35 48 41 3 25 58 27 193 -16 35 18 41 36 19 10 34 36 55 37 3 24 -109 0 0 35 53 50 3 26 8 26 194 -17 35 23 48 36 24 22 34 41 58 37 8 40 -108 0 0 35 59 53 3 26 19 26 195 -18 35 29 47 36 30 29 34 47 52 37 14 52 -107 0 0 36 6 49 3 26 29 26 196 -18 35 36 39 36 37 29 34 54 40 37 21 58 -106 0 0 36 14 38 3 26 39 25 197 -19 35 44 24 36 45 23 35 2 19 37 29 59 -105 0 0 36 23 20 3 26 49 25 198 -20 35 53 2 36 54 10 35 10 50 37 38 54 -104 0 0 36 32 56 3 26 59 25 199 -20 36 2 32 37 3 52 35 20 13 37 48 45 -103 0 0 36 43 25 3 27 8 24 200 -21 36 12 54 37 14 27 35 30 27 37 59 29 -102 0 0 36 54 46 3 27 18 24 201 -21 36 24 9 37 25 55 35 41 33 38 11 8 -101 0 0 37 7 0 3 27 27 23 202 -22 36 36 16 37 38 16 35 53 31 38 23 41 -100 0 0 37 20 7 3 27 36 23 203 -22 36 49 15 37 51 31 36 6 20 38 37 8 - 99 0 0 37 34 6 3 27 45 22 204 -23 37 3 6 38 5 39 36 20 0 38 51 29 - 98 0 0 37 48 57 3 27 54 22 205 -23 37 17 49 38 20 40 36 34 30 39 6 44 - 97 0 0 38 4 41 3 28 3 21 206 -24 37 33 23 38 36 33 36 49 52 39 22 52 - 96 0 0 38 21 16 3 28 11 20 206 -24 37 49 48 38 53 19 37 6 4 39 39 54 - 95 0 0 38 38 43 3 28 19 20 207 -25 38 7 5 39 10 57 37 23 6 39 57 50 - 94 0 0 38 57 2 3 28 27 19 208 -25 38 25 12 39 29 28 37 40 58 40 16 38 - 93 0 0 39 16 11 3 28 34 18 209 -26 38 44 10 39 48 50 37 59 40 40 36 20 - 92 0 0 39 36 12 3 28 42 18 210 -26 39 3 58 40 9 4 38 19 12 40 56 55 - 91 0 0 39 57 4 3 28 49 17 211 -26 39 24 36 40 30 10 38 39 32 41 18 22 - 90 0 0 40 18 46 3 28 56 16 211 -26 39 46 4 40 52 7 39 0 42 41 40 41 - 89 0 0 40 41 18 3 29 2 16 212 -27 40 8 21 41 14 54 39 22 40 42 3 53 - 88 0 0 41 4 40 3 29 9 15 213 -27 40 31 28 41 38 33 39 45 26 42 27 56 - 87 0 0 41 28 51 3 29 15 14 214 -27 40 55 23 42 3 1 40 9 0 42 52 52 - 86 0 0 41 53 51 3 29 20 13 215 -27 41 20 7 42 28 20 40 33 21 43 18 38 - 85 0 0 42 19 41 3 29 26 13 215 -27 41 45 38 42 54 28 40 58 29 43 45 16 - 84 0 0 42 46 19 3 29 31 12 216 -27 42 11 57 43 21 26 41 24 24 44 12 44 - 83 0 0 43 13 44 3 29 35 11 217 -28 42 39 4 43 49 12 41 51 5 44 41 3 - 82 0 0 43 41 57 3 29 40 10 218 -28 43 6 57 44 17 47 42 18 31 45 10 11 - 81 0 0 44 10 57 3 29 44 9 218 -28 43 35 35 44 47 10 42 46 42 45 40 10 - 80 0 0 44 40 44 3 29 47 8 219 -28 44 5 0 45 17 21 43 15 38 46 10 58 - 79 0 0 45 11 17 3 29 51 8 220 -27 44 35 10 45 48 18 43 45 17 46 42 34 - 78 0 0 45 42 35 3 29 54 7 221 -27 45 6 4 46 20 3 44 15 40 47 14 59 - 77 0 0 46 14 38 3 29 56 6 221 -27 45 37 42 46 52 33 44 46 45 47 48 13 - 76 0 0 46 47 26 3 29 59 5 222 -27 46 10 3 47 25 49 45 18 32 48 22 14 - 75 0 0 47 20 57 3 30 0 4 223 -27 46 43 6 47 59 50 45 51 0 48 57 2 - 74 0 0 47 55 11 3 30 2 3 224 -27 47 16 51 48 34 35 46 24 8 49 32 36 - 73 0 0 48 30 7 3 30 3 2 224 -26 47 51 18 49 10 4 .. .. .. 50 8 57 - 72 0 0 49 5 45 3 30 4 2 225 -26 48 26 24 49 46 16 .. .. .. 50 46 3 - 71 0 0 49 42 3 3 30 4 1 226 -26 49 2 10 50 23 10 .. .. .. .. .. .. Uncertainty in time = +/- 4 secs Prediction of 2012 Jul 8.0 Data for the target star ------------------------ * name: TYC 6819-07252-1 * constellation : Ophiuchus * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 08 10.9309 DE: -26 21 36.909 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .026, .032 ) * V mag [mag]: 12.0 * B mag [mag]: 12.2 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (138) Tolosa approx. diameter [km]: 52 approx. diameter ["]: .048 distance from Earth [AU]: 1.50200 * orbital information: orbit source: Preston date of fit: 2012 Jul 07 source of used astrometry: FASTT TMO MPC (via Astdys) number of used observations: 1338 number of rejected observations: 113 time covered by the observations: 1905 Nov 30 - 2012 Jun 28 1 sigma uncertainty ellipse (major, minor, PA): 0.018, 0.011, 100° remarks: * orbital elements for (138) Tolosa : Mean anomaly = 338.78679659 deg Arg. of pericenter = 259.84736052 deg Long. of node = 54.90772671 deg Inclination = 3.20683217 deg Eccentricity = 0.16179256 Semimajor axis = 2.44901154 AU Perihelion dist = 2.05277971 AU Mag: H = 8.69, G = 0.15 Epoch of elements : MJD 56159.14200000 TDT (2012 Aug 20.142) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Aug 20 138 Tolosa 3h 24.4m UT 12.0 17 8 10.931-26 21 36.91TYC 6819-07252-1 12.2 12.4 52 6.0 1.502 2.129 -1.70 -122.9169 -26.358 129.76 12.33 3.4059 0.05306 0.88036 4.88329 -0.29014 0.00490 -0.00032 2000 336.4357622012 811.00000259.847361 54.907727 3.2068320.16179256 2.4490115 2.0527797 8.8 5.00.15 RATE 2.5716860 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.034 0.032 1 1.71 0.034 0 0-1 1 056116.0020120820_7252-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Jul 07, 23:29 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org