IOTA/IOTA-ES occultation update for (655) Briseis / UCAC2 24918385 event on 2009 Jul 02, 21:37 UT Visible from Summary ------- On 2009 Jul 02 UT, the 31 km diameter asteroid (655) Briseis will occult a 11.8 mag star in the constellation Sagittarius for observers along a path across . In the case of an occultation, the combined light of the asteroid and the star will drop by 2.4 mag to 14.1 mag (the magnitude of the asteroid) for at most 2.4 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: 8 * date and approx. time of event: 2009 Jul 02, 21:34 - 2009 Jul 02, 21:41 UT * magnitude of target star: 11.8 * magnitude drop [mag]: 2.4 * estimated maximum duration [s]: 2.4 * Moon: 83 % sunlit, 44° distance * Sun: 171° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 71 * 1 sigma uncertainty interval [path widths]: +/- 7.98 * 1 sigma uncertainty interval [seconds]: +/- 14.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .131 +/- .160) * 1 sigma uncertainty ellipse (major, minor, PA): ( .160", .131", 0° ) * approx speed of asteroid's shadow [km/s]: 13.1062 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC2 24918385 by 655 Briseis on 2009 Jul 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 ' " Longitude Longitude Longitude Longitude Latitude Latitude Latitude Latitude 68 0 0 63 31 32 21 34 12 3 216 0 64 0 36 63 3 11 .. .. .. .. .. .. 67 0 0 63 2 36 21 34 13 4 215 -1 63 31 24 62 34 31 .. .. .. .. .. .. 66 0 0 62 33 43 21 34 14 5 214 -2 63 2 14 62 5 53 .. .. .. .. .. .. 65 0 0 62 4 53 21 34 15 5 213 -2 62 33 8 61 37 18 .. .. .. .. .. .. 64 0 0 61 36 8 21 34 17 6 212 -3 62 4 6 61 8 49 .. .. .. .. .. .. 63 0 0 61 7 29 21 34 18 7 211 -4 61 35 11 60 40 25 .. .. .. .. .. .. 62 0 0 60 38 57 21 34 20 7 211 -4 61 6 23 60 12 9 .. .. .. .. .. .. 61 0 0 60 10 35 21 34 21 8 210 -5 60 37 45 59 44 1 .. .. .. .. .. .. 60 0 0 59 42 22 21 34 23 9 209 -5 60 9 16 59 16 3 .. .. .. .. .. .. 59 0 0 59 14 21 21 34 25 9 208 -6 59 40 59 58 48 17 69 8 56 52 47 57 58 0 0 58 46 32 21 34 28 10 207 -7 59 12 55 58 20 43 68 30 8 52 22 57 57 0 0 58 18 57 21 34 30 11 206 -7 58 45 4 57 53 22 67 52 4 51 58 9 56 0 0 57 51 36 21 34 33 11 205 -8 58 17 28 57 26 15 67 14 44 51 33 35 55 0 0 57 24 31 21 34 35 12 204 -8 57 50 8 56 59 24 66 38 8 51 9 14 54 0 0 56 57 42 21 34 38 12 203 -9 57 23 5 56 32 49 66 2 13 50 45 8 53 0 0 56 31 11 21 34 41 13 203 -10 56 56 20 56 6 31 65 27 1 50 21 17 52 0 0 56 4 58 21 34 44 14 202 -10 56 29 53 55 40 32 64 52 29 49 57 42 51 0 0 55 39 5 21 34 48 14 201 -11 56 3 46 55 14 52 64 18 39 49 34 24 50 0 0 55 13 32 21 34 51 15 200 -11 55 38 0 54 49 31 63 45 29 49 11 24 49 0 0 54 48 20 21 34 55 15 199 -12 55 12 35 54 24 32 63 12 59 48 48 43 48 0 0 54 23 30 21 34 58 16 198 -12 54 47 32 53 59 54 62 41 10 48 26 20 47 0 0 53 59 2 21 35 2 17 197 -13 54 22 52 53 35 38 62 10 0 48 4 17 46 0 0 53 34 58 21 35 6 17 196 -13 53 58 35 53 11 45 61 39 31 47 42 34 45 0 0 53 11 17 21 35 10 18 195 -14 53 34 43 52 48 15 61 9 41 47 21 11 44 0 0 52 48 1 21 35 15 18 194 -14 53 11 15 52 25 10 60 40 31 47 0 11 43 0 0 52 25 10 21 35 19 19 193 -15 52 48 13 52 2 29 60 12 1 46 39 32 42 0 0 52 2 44 21 35 23 19 192 -15 52 25 36 51 40 14 59 44 10 46 19 16 41 0 0 51 40 45 21 35 28 20 191 -15 52 3 26 51 18 25 59 16 59 45 59 23 40 0 0 51 19 12 21 35 33 20 190 -16 51 41 43 50 57 2 58 50 28 45 39 53 39 0 0 50 58 7 21 35 38 21 190 -16 51 20 28 50 36 6 58 24 36 45 20 47 38 0 0 50 37 29 21 35 43 21 189 -17 50 59 41 50 15 37 57 59 24 45 2 6 37 0 0 50 17 19 21 35 48 22 188 -17 50 39 22 49 55 37 57 34 51 44 43 49 36 0 0 49 57 38 21 35 53 22 187 -17 50 19 31 49 36 4 57 10 58 44 25 58 35 0 0 49 38 26 21 35 58 22 186 -18 50 0 11 49 17 0 56 47 44 44 8 32 34 0 0 49 19 43 21 36 3 23 185 -18 49 41 19 48 58 25 56 25 10 43 51 32 33 0 0 49 1 30 21 36 9 23 184 -18 49 22 58 48 40 20 56 3 15 43 34 59 32 0 0 48 43 46 21 36 14 23 183 -18 49 5 7 48 22 44 55 42 0 43 18 52 31 0 0 48 26 33 21 36 19 24 182 -19 48 47 46 48 5 38 55 21 25 43 3 13 30 0 0 48 9 51 21 36 25 24 181 -19 48 30 56 47 49 3 55 1 29 42 48 0 29 0 0 47 53 39 21 36 31 24 180 -19 48 14 38 47 32 58 54 42 13 42 33 16 28 0 0 47 37 59 21 36 36 24 179 -19 47 58 51 47 17 24 54 23 37 42 18 59 27 0 0 47 22 50 21 36 42 25 177 -19 47 43 35 47 2 21 54 5 40 42 5 10 26 0 0 47 8 12 21 36 48 25 176 -19 47 28 52 46 47 49 53 48 23 41 51 50 25 0 0 46 54 7 21 36 54 25 175 -19 47 14 40 46 33 49 53 31 45 41 38 59 24 0 0 46 40 33 21 37 0 25 174 -20 47 1 1 46 20 21 53 15 47 41 26 36 23 0 0 46 27 32 21 37 5 25 173 -20 46 47 55 46 7 25 53 0 29 41 14 43 22 0 0 46 15 4 21 37 11 26 172 -20 46 35 21 45 55 2 52 45 51 41 3 19 21 0 0 46 3 8 21 37 17 26 171 -20 46 23 20 45 43 10 52 31 52 40 52 24 20 0 0 45 51 44 21 37 23 26 170 -20 46 11 52 45 31 52 52 18 33 40 41 59 19 0 0 45 40 54 21 37 29 26 169 -20 46 0 58 45 21 6 52 5 54 40 32 4 18 0 0 45 30 37 21 37 35 26 168 -20 45 50 37 45 10 53 51 53 55 40 22 39 17 0 0 45 20 54 21 37 41 26 167 -20 45 40 49 45 1 12 51 42 35 40 13 44 16 0 0 45 11 43 21 37 47 26 166 -19 45 31 35 44 52 6 51 31 55 40 5 20 15 0 0 45 3 6 21 37 53 26 165 -19 45 22 55 44 43 32 51 21 55 39 57 26 14 0 0 44 55 3 21 37 59 26 164 -19 45 14 49 44 35 32 51 12 35 39 50 3 13 0 0 44 47 34 21 38 5 26 163 -19 45 7 17 44 28 5 51 3 55 39 43 10 12 0 0 44 40 39 21 38 11 26 162 -19 45 0 19 44 21 13 50 55 55 39 36 49 11 0 0 44 34 17 21 38 17 25 161 -19 44 53 55 44 14 54 50 48 34 39 30 58 10 0 0 44 28 30 21 38 23 25 160 -18 44 48 5 44 9 8 50 41 54 39 25 38 9 0 0 44 23 17 21 38 29 25 159 -18 44 42 50 44 3 57 50 35 53 39 20 50 8 0 0 44 18 38 21 38 34 25 158 -18 44 38 10 43 59 20 50 30 33 39 16 33 7 0 0 44 14 33 21 38 40 25 157 -18 44 34 4 43 55 16 50 25 52 39 12 47 6 0 0 44 11 3 21 38 46 24 156 -17 44 30 32 43 51 47 50 21 52 39 9 32 5 0 0 44 8 7 21 38 52 24 155 -17 44 27 36 43 48 53 50 18 31 39 6 50 4 0 0 44 5 46 21 38 57 24 154 -17 44 25 14 43 46 32 50 15 51 39 4 38 3 0 0 44 3 59 21 39 3 24 153 -16 44 23 26 43 44 46 50 13 51 39 2 58 2 0 0 44 2 47 21 39 8 23 152 -16 44 22 14 43 43 34 50 12 31 39 1 50 1 0 0 44 2 10 21 39 14 23 151 -16 44 21 37 43 42 57 50 11 51 39 1 14 0 0 0 44 2 7 21 39 19 23 150 -15 44 21 34 43 42 54 50 11 52 39 1 9 - 1 0 0 44 2 39 21 39 24 22 149 -15 44 22 6 43 43 26 50 12 33 39 1 36 - 2 0 0 44 3 46 21 39 29 22 148 -15 44 23 14 43 44 32 50 13 54 39 2 35 - 3 0 0 44 5 28 21 39 34 22 147 -14 44 24 56 43 46 13 50 15 55 39 4 6 - 4 0 0 44 7 44 21 39 39 21 147 -14 44 27 14 43 48 28 50 18 38 39 6 8 - 5 0 0 44 10 35 21 39 44 21 146 -13 44 30 6 43 51 18 50 22 0 39 8 43 - 6 0 0 44 14 2 21 39 49 20 145 -13 44 33 34 43 54 43 50 26 3 39 11 49 - 7 0 0 44 18 2 21 39 54 20 144 -12 44 37 37 43 58 42 50 30 47 39 15 27 - 8 0 0 44 22 38 21 39 59 19 143 -12 44 42 14 44 3 16 50 36 11 39 19 36 - 9 0 0 44 27 49 21 40 3 19 142 -11 44 47 27 44 8 24 50 42 16 39 24 18 - 10 0 0 44 33 34 21 40 7 18 141 -11 44 53 15 44 14 7 50 49 1 39 29 31 - 11 0 0 44 39 54 21 40 12 18 140 -10 44 59 38 44 20 25 50 56 28 39 35 16 - 12 0 0 44 46 49 21 40 16 17 140 -9 45 6 35 44 27 17 51 4 35 39 41 33 - 13 0 0 44 54 18 21 40 20 17 139 -9 45 14 8 44 34 43 51 13 23 39 48 21 - 14 0 0 45 2 23 21 40 24 16 138 -8 45 22 16 44 42 44 51 22 52 39 55 41 - 15 0 0 45 11 1 21 40 28 16 137 -8 45 30 58 44 51 19 51 33 2 40 3 32 - 16 0 0 45 20 15 21 40 31 15 136 -7 45 40 15 45 0 29 51 43 53 40 11 55 - 17 0 0 45 30 2 21 40 35 14 136 -6 45 50 7 45 10 12 51 55 25 40 20 49 - 18 0 0 45 40 25 21 40 38 14 135 -6 46 0 34 45 20 30 52 7 38 40 30 14 - 19 0 0 45 51 21 21 40 41 13 134 -5 46 11 35 45 31 22 52 20 32 40 40 10 - 20 0 0 46 2 52 21 40 45 13 133 -5 46 23 11 45 42 48 52 34 8 40 50 38 - 21 0 0 46 14 56 21 40 47 12 132 -4 46 35 20 45 54 48 52 48 24 41 1 36 - 22 0 0 46 27 35 21 40 50 11 132 -3 46 48 5 46 7 21 53 3 22 41 13 5 - 23 0 0 46 40 47 21 40 53 11 131 -3 47 1 23 46 20 28 53 19 2 .. .. .. - 24 0 0 46 54 33 21 40 55 10 130 -2 47 15 15 46 34 8 53 35 23 .. .. .. - 25 0 0 47 8 53 21 40 58 9 129 -1 47 29 41 46 48 21 53 52 25 .. .. .. - 26 0 0 47 23 45 21 41 0 9 129 -1 47 44 40 47 3 8 54 10 8 .. .. .. Uncertainty in time = +/- 19 secs [Prediction of 2008 Mar 20.0] Data for the target star ------------------------ * name: UCAC2 24918385 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 17 53.4294 DE: -18 02 42.711 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .127, .159 ) * V mag [mag]: 11.8 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (655) Briseis approx. diameter [km]: 31 approx. diameter ["]: .020 distance from Earth [AU]: 2.15200 * orbital information: orbit source: Preston date of fit: 2008 Mar 20 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1020 number of rejected observations: 56 time covered by the observations: 1909 Feb 18 - 2008 Feb 09 1 sigma uncertainty ellipse (major, minor, PA): 0.032, 0.018, 93° remarks: * orbital elements for (655) Briseis : Mean anomaly = 234.33473570 deg Arg. of pericenter = 279.65514528 deg Long. of node = 130.18516555 deg Inclination = 6.50600192 deg Eccentricity = 0.09091430 Semimajor axis = 2.98758407 AU Perihelion dist = 2.71596995 AU Mag: H = 9.95, G = 0.15 Epoch of elements : MJD 55014.90100000 TDT (2009 Jul 02.901) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Jul 2 655 Briseis 21h 37.7m UT 11.8 18 17 53.429-18 2 42.71UCAC2 24918385 0.0 14.1 31 2.4 2.152 -2.090 -4.98 28.9957 -18.043 -143.38 22.97 21.6281 -0.14804 0.88619 -7.29657 -1.21792 0.00070 -0.00049 2000 233.3993122009 628.00000279.655145130.185166 6.5060020.09091430 2.9875841 2.7159700 9.6 5.00.15 RATE 1.9086390 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.160 0.131 0 8.98 0.159 0 54545.5020090702_918385 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2008 Mar 20, 10:11 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org