IOTA/IOTA-ES occultation update for (494) Virtus / TYC 7361-00191-1 event on 2009 Jul 11, 05:36 UT Visible from SE USA, Mexico Summary ------- On 2009 Jul 11 UT, the 86 km diameter asteroid (494) Virtus will occult a 12.1 mag star in the constellation Scorpius for observers along a path across SE USA, Mexico. In the case of an occultation, the combined light of the asteroid and the star will drop by 1.5 mag to 13.3 mag (the magnitude of the asteroid) for at most 11.6 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: 96 * date and approx. time of event: 2009 Jul 11, 05:27 - 2009 Jul 11, 05:43 UT * magnitude of target star: 12.1 * magnitude drop [mag]: 1.5 * estimated maximum duration [s]: 11.6 * Moon: 87 % sunlit, 73° distance * Sun: 149° distance * rough path description: SE USA, Mexico The occultation path -------------------- * approximate projected width [km]: 146 * 1 sigma uncertainty interval [path widths]: +/- 0.42 * 1 sigma uncertainty interval [seconds]: +/- 5.1 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .032 +/- .026) * 1 sigma uncertainty ellipse (major, minor, PA): ( .032", .026", 96° ) * approx speed of asteroid's shadow [km/s]: 7.3899 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 7361-00191-1 by 494 Virtus on 2009 Jul 11 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 -153 37 39 40 0 0 5 43 22 12 149 -1 -152 17 55 -154 55 48 -151 9 37 -156 0 19 -152 10 21 39 0 0 5 43 13 13 150 -2 -150 49 50 -153 29 10 -149 40 48 -154 34 11 -150 40 24 38 0 0 5 43 4 15 151 -4 -149 18 55 -152 0 5 -148 8 58 -153 5 44 -149 7 33 37 0 0 5 42 54 16 153 -5 -147 44 51 -150 28 17 -146 33 45 -151 34 43 -147 31 25 36 0 0 5 42 42 18 154 -7 -146 7 16 -148 53 27 -144 54 47 -150 0 52 -145 51 38 35 0 0 5 42 29 19 155 -8 -144 25 42 -147 15 14 -143 11 33 -148 23 49 -144 7 43 34 0 0 5 42 14 20 156 -10 -142 39 39 -145 33 12 -141 23 28 -146 43 12 -142 19 5 33 0 0 5 41 58 22 157 -12 -140 48 26 -143 46 51 -139 29 47 -144 58 33 -140 25 2 32 0 0 5 41 39 23 159 -14 -138 51 14 -141 55 33 -137 29 35 -143 9 19 -138 24 42 31 0 0 5 41 19 25 160 -16 -136 47 2 -139 58 33 -135 21 39 -141 14 48 Latitude Latitude Latitude Latitude -138 0 0 30 48 7 5 41 15 25 161 -16 31 34 48 30 2 25 32 14 51 29 24 45 -137 0 0 30 19 49 5 41 4 26 161 -17 31 6 5 29 34 30 31 45 46 28 57 9 -136 0 0 29 52 21 5 40 54 27 162 -18 30 38 14 29 7 25 31 17 34 28 30 22 -135 0 0 29 25 44 5 40 43 27 163 -19 30 11 15 28 41 9 30 50 14 28 4 23 -134 0 0 28 59 58 5 40 32 28 164 -20 29 45 6 28 15 43 30 23 46 27 39 13 -133 0 0 28 35 1 5 40 20 29 165 -21 29 19 49 27 51 6 29 58 10 27 14 51 -132 0 0 28 10 54 5 40 9 29 166 -22 28 55 22 27 27 18 29 33 26 26 51 18 -131 0 0 27 47 37 5 39 57 30 166 -22 28 31 46 27 4 19 29 9 34 26 28 33 -130 0 0 27 25 10 5 39 45 30 167 -23 28 9 1 26 42 9 28 46 32 26 6 37 -129 0 0 27 3 32 5 39 33 31 168 -24 27 47 6 26 20 47 28 24 22 25 45 28 -128 0 0 26 42 44 5 39 21 31 169 -25 27 26 1 26 0 14 28 3 2 25 25 7 -127 0 0 26 22 44 5 39 9 32 170 -26 27 5 46 25 40 30 27 42 34 25 5 35 -126 0 0 26 3 34 5 38 56 32 171 -27 26 46 21 25 21 33 27 22 55 24 46 50 -125 0 0 25 45 13 5 38 44 33 172 -27 26 27 46 25 3 25 27 4 7 24 28 52 -124 0 0 25 27 40 5 38 31 33 173 -28 26 9 59 24 46 5 26 46 9 24 11 42 -123 0 0 25 10 56 5 38 18 34 174 -29 25 53 3 24 29 33 26 29 1 23 55 20 -122 0 0 24 55 0 5 38 6 34 175 -30 25 36 55 24 13 48 26 12 43 23 39 44 -121 0 0 24 39 52 5 37 53 34 176 -31 25 21 36 23 58 51 25 57 14 23 24 56 -120 0 0 24 25 33 5 37 40 35 177 -31 25 7 6 23 44 42 25 42 35 23 10 54 -119 0 0 24 12 1 5 37 27 35 178 -32 24 53 24 23 31 20 25 28 45 22 57 40 -118 0 0 23 59 18 5 37 14 35 179 -33 24 40 32 23 18 45 25 15 44 22 45 12 -117 0 0 23 47 22 5 37 1 35 180 -33 24 28 27 23 6 57 25 3 32 22 33 30 -116 0 0 23 36 13 5 36 48 35 181 -34 24 17 11 22 55 56 24 52 8 22 22 36 -115 0 0 23 25 52 5 36 34 36 181 -35 24 6 43 22 45 43 24 41 34 22 12 28 -114 0 0 23 16 19 5 36 21 36 182 -35 23 57 3 22 36 16 24 31 48 22 3 6 -113 0 0 23 7 33 5 36 8 36 184 -36 23 48 10 22 27 35 24 22 50 21 54 30 -112 0 0 22 59 34 5 35 55 36 185 -37 23 40 6 22 19 42 24 14 41 21 46 41 -111 0 0 22 52 23 5 35 42 36 186 -37 23 32 50 22 12 35 24 7 20 21 39 38 -110 0 0 22 45 58 5 35 28 36 187 -38 23 26 21 22 6 15 24 0 48 21 33 21 -109 0 0 22 40 21 5 35 15 36 188 -38 23 20 40 22 0 41 23 55 3 21 27 50 -108 0 0 22 35 31 5 35 2 36 189 -39 23 15 46 21 55 54 23 50 7 21 23 5 -107 0 0 22 31 28 5 34 49 36 189 -39 23 11 41 21 51 53 23 45 59 21 19 7 -106 0 0 22 28 12 5 34 36 36 190 -40 23 8 23 21 48 39 23 42 39 21 15 54 -105 0 0 22 25 43 5 34 23 36 191 -40 23 5 52 21 46 11 23 40 7 21 13 28 -104 0 0 22 24 0 5 34 9 35 192 -41 23 4 9 21 44 30 23 38 23 21 11 47 -103 0 0 22 23 5 5 33 56 35 193 -41 23 3 14 21 43 35 23 37 28 21 10 53 -102 0 0 22 22 57 5 33 44 35 194 -42 23 3 6 21 43 27 23 37 20 21 10 44 -101 0 0 22 23 37 5 33 31 35 195 -42 23 3 46 21 44 6 23 38 1 21 11 22 -100 0 0 22 25 3 5 33 18 35 196 -42 23 5 13 21 45 31 23 39 30 21 12 46 - 99 0 0 22 27 16 5 33 5 34 197 -43 23 7 29 21 47 42 23 41 47 21 14 56 - 98 0 0 22 30 17 5 32 53 34 198 -43 23 10 32 21 50 41 23 44 52 21 17 53 - 97 0 0 22 34 5 5 32 40 34 199 -43 23 14 24 21 54 26 23 48 46 21 21 36 - 96 0 0 22 38 41 5 32 28 33 200 -43 23 19 3 21 58 58 23 53 29 21 26 5 - 95 0 0 22 44 4 5 32 15 33 201 -43 23 24 30 22 4 17 23 59 0 21 31 21 - 94 0 0 22 50 15 5 32 3 32 202 -44 23 30 46 22 10 24 24 5 20 21 37 24 - 93 0 0 22 57 14 5 31 51 32 202 -44 23 37 50 22 17 17 24 12 29 21 44 13 - 92 0 0 23 5 1 5 31 39 32 203 -44 23 45 43 22 24 58 24 20 27 21 51 49 - 91 0 0 23 13 36 5 31 27 31 204 -44 23 54 25 22 33 27 24 29 14 22 0 13 - 90 0 0 23 22 59 5 31 16 31 205 -44 24 3 55 22 42 43 24 38 51 22 9 23 - 89 0 0 23 33 10 5 31 4 30 206 -44 24 14 14 22 52 47 24 49 18 22 19 21 - 88 0 0 23 44 10 5 30 53 29 207 -44 24 25 23 23 3 39 25 0 34 22 30 6 - 87 0 0 23 55 59 5 30 42 29 207 -44 24 37 21 23 15 19 25 12 40 22 41 39 - 86 0 0 24 8 36 5 30 30 28 208 -44 24 50 8 23 27 47 25 25 36 22 54 0 - 85 0 0 24 22 3 5 30 20 28 209 -44 25 3 46 23 41 4 25 39 23 23 7 9 - 84 0 0 24 36 20 5 30 9 27 210 -43 25 18 13 23 55 9 25 54 0 23 21 6 - 83 0 0 24 51 25 5 29 59 26 210 -43 25 33 31 24 10 4 26 9 29 23 35 51 - 82 0 0 25 7 21 5 29 48 26 211 -43 25 49 39 24 25 47 26 25 48 23 51 25 - 81 0 0 25 24 7 5 29 38 25 212 -43 26 6 39 24 42 20 26 42 59 24 7 48 - 80 0 0 25 41 43 5 29 29 24 212 -42 26 24 29 24 59 43 27 1 2 24 25 0 - 79 0 0 26 0 9 5 29 19 24 213 -42 26 43 10 25 17 55 27 19 57 24 43 1 - 78 0 0 26 19 26 5 29 10 23 214 -42 27 2 43 25 36 57 27 39 44 25 1 51 - 77 0 0 26 39 35 5 29 1 22 214 -41 27 23 8 25 56 50 28 0 23 25 21 31 - 76 0 0 27 0 34 5 28 52 21 215 -41 27 44 25 26 17 33 28 21 55 25 42 1 - 75 0 0 27 22 25 5 28 43 21 216 -40 28 6 34 26 39 7 28 44 21 26 3 21 - 74 0 0 27 45 8 5 28 35 20 216 -40 28 29 36 27 1 31 29 7 40 26 25 31 - 73 0 0 28 8 42 5 28 27 19 217 -39 28 53 31 27 24 47 29 31 52 26 48 31 - 72 0 0 28 33 9 5 28 19 18 217 -39 29 18 18 27 48 54 29 56 59 27 12 23 - 71 0 0 28 58 28 5 28 12 17 218 -38 29 44 0 28 13 52 30 23 0 27 37 5 - 70 0 0 29 24 40 5 28 5 16 219 -38 30 10 35 28 39 43 30 49 56 28 2 38 - 69 0 0 29 51 45 5 27 58 16 219 -37 30 38 4 29 6 25 31 17 46 28 29 2 - 68 0 0 30 19 43 5 27 52 15 220 -36 31 6 27 29 33 59 31 46 32 28 56 18 - 67 0 0 30 48 35 5 27 46 14 220 -36 31 35 45 30 2 26 32 16 13 29 24 25 - 66 0 0 31 18 19 5 27 40 13 221 -35 32 5 57 30 31 45 32 46 50 29 53 23 - 65 0 0 31 48 58 5 27 35 12 221 -34 32 37 4 31 1 57 33 18 22 30 23 14 - 64 0 0 32 20 30 5 27 30 11 222 -33 33 9 6 31 33 1 33 50 51 30 53 56 - 63 0 0 32 52 56 5 27 25 10 223 -33 33 42 3 32 4 58 34 24 16 31 25 30 - 62 0 0 33 26 16 5 27 21 9 223 -32 34 15 56 32 37 48 34 58 38 31 57 57 - 61 0 0 34 0 30 5 27 17 8 224 -31 34 50 44 33 11 31 35 33 57 32 31 14 - 60 0 0 34 35 39 5 27 14 7 224 -30 35 26 27 33 46 6 36 10 12 33 5 24 - 59 0 0 35 11 41 5 27 11 6 225 -29 36 3 6 34 21 35 36 47 24 33 40 26 - 58 0 0 35 48 37 5 27 9 5 226 -28 36 40 40 34 57 55 37 25 33 34 16 19 - 57 0 0 36 26 27 5 27 7 4 226 -28 37 19 10 35 35 9 38 4 39 34 53 3 - 56 0 0 37 5 11 5 27 5 3 227 -27 37 58 35 36 13 14 38 44 42 35 30 39 - 55 0 0 37 44 48 5 27 4 2 227 -26 38 38 55 36 52 12 39 25 41 .. .. .. - 54 0 0 38 25 18 5 27 3 1 228 -25 39 20 10 37 32 1 .. .. .. .. .. .. Uncertainty in time = +/- 6 secs Prediction of 2009 Jun 25.0 Data for the target star ------------------------ * name: TYC 7361-00191-1 * constellation : Scorpius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 17 07 18.0678 DE: -31 04 58.457 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .023, .023 ) * V mag [mag]: 12.1 * B mag [mag]: 12.4 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (494) Virtus approx. diameter [km]: 86 approx. diameter ["]: .062 distance from Earth [AU]: 1.90200 * orbital information: orbit source: Preston date of fit: 2009 Jun 24 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1234 number of rejected observations: 111 time covered by the observations: 1902 Oct 07 - 2009 Jun 13 1 sigma uncertainty ellipse (major, minor, PA): 0.022, 0.012, 102° remarks: * orbital elements for (494) Virtus : Mean anomaly = 11.88471616 deg Arg. of pericenter = 217.66666704 deg Long. of node = 38.36996691 deg Inclination = 7.07557791 deg Eccentricity = 0.05713056 Semimajor axis = 2.98745834 AU Perihelion dist = 2.81678319 AU Mag: H = 9.06, G = 0.15 Epoch of elements : MJD 55023.23300000 TDT (2009 Jul 11.233) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Jul 11 494 Virtus 5h 35.5m UT 12.1 17 7 18.068-31 4 58.46TYC 7361-00191-1 12.4 13.3 86 11.6 1.902 -1.488 2.36 -116.3078 -31.083 97.51 22.08 5.5910 0.09961 0.80296 -4.13987 0.50930 0.00283 0.00042 2000 11.2676142009 7 8.00000217.666667 38.369967 7.0755780.05713056 2.9874583 2.8167832 9.0 5.00.15 RATE 1.9087600 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.032 0.026 96 1.42 0.026 0 55007.0020090711_0191-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2009 Jun 24, 17:51 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org