IOTA/IOTA-ES occultation update for (267) Tirza / TYC 6896-00287-1 event on 2012 Nov 18, 08:16 UT Visible from Japan Summary ------- On 2012 Nov 18 UT, the 56 km diameter asteroid (267) Tirza will occult a 10.4 mag star in the constellation Sagittarius for observers along a path across Japan. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.4 mag to 15.8 mag (the magnitude of the asteroid) for at most 1.7 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: 48 * date and approx. time of event: 2012 Nov 18, 08:17 - 2012 Nov 18, 08:18 UT * geocentric midpoint of event [JD]: 2456249.84502083 * magnitude of target star: 10.4 * magnitude drop [mag]: 5.4 * estimated maximum duration [s]: 1.7 * Moon: 26 % sunlit, 9° distance * Sun: 62° distance * rough path description: Japan The occultation path -------------------- * approximate projected width [km]: 92 * 1 sigma uncertainty interval [path widths]: +/- 1.34 * 1 sigma uncertainty interval [seconds]: +/- 1.7 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .029 +/- .037) * 1 sigma uncertainty ellipse (major, minor, PA): ( .037", .029", 360° ) * approx speed of asteroid's shadow [km/s]: 32.9410 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of TYC 6896-00287-1 by 267 Tirza on 2012 Nov 18 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 165 3 34 56 0 0 8 18 46 0 221 -29 ... .. .. 164 5 0 ... .. .. 161 26 35 163 32 39 55 0 0 8 18 46 1 219 -28 164 29 53 162 35 7 ... .. .. 159 59 26 162 2 24 54 0 0 8 18 46 3 218 -27 162 58 41 161 5 48 ... .. .. 158 32 32 160 32 37 53 0 0 8 18 46 4 217 -27 161 28 4 159 36 52 ... .. .. 157 5 44 159 3 8 52 0 0 8 18 45 5 216 -26 159 57 49 158 8 6 ... .. .. 155 38 51 157 33 45 51 0 0 8 18 44 7 215 -25 158 27 47 156 39 22 ... .. .. 154 11 43 156 4 18 50 0 0 8 18 43 8 213 -24 156 57 47 155 10 28 159 19 26 152 44 10 154 34 38 49 0 0 8 18 42 9 212 -23 155 27 38 153 41 14 157 47 55 151 16 3 153 4 32 48 0 0 8 18 41 11 211 -22 153 57 9 152 11 30 156 16 19 149 47 11 151 33 52 47 0 0 8 18 39 12 210 -21 152 26 11 150 41 6 154 44 27 148 17 24 150 2 26 46 0 0 8 18 37 14 209 -19 150 54 33 149 9 51 153 12 9 146 46 30 148 30 3 45 0 0 8 18 35 15 207 -18 149 22 3 147 37 34 151 39 13 145 14 17 146 56 32 44 0 0 8 18 33 16 206 -17 147 48 31 146 4 2 150 5 29 143 40 34 145 21 40 43 0 0 8 18 31 18 205 -16 146 13 43 144 29 3 148 30 45 142 5 5 143 45 12 42 0 0 8 18 28 19 204 -14 144 37 27 142 52 22 146 54 48 140 27 35 142 6 56 41 0 0 8 18 25 21 202 -13 142 59 28 141 13 45 145 17 26 138 47 47 140 26 32 40 0 0 8 18 22 22 201 -11 141 19 31 139 32 53 143 38 23 137 5 21 138 43 44 39 0 0 8 18 18 23 199 -10 139 37 16 137 49 26 141 57 24 135 19 53 136 58 8 38 0 0 8 18 14 25 198 -8 137 52 25 136 3 3 140 14 11 133 30 57 135 9 21 37 0 0 8 18 10 26 196 -6 136 4 32 134 13 16 138 28 23 131 37 59 133 16 52 36 0 0 8 18 5 28 194 -5 134 13 11 132 19 33 136 39 37 129 40 22 131 20 5 35 0 0 8 18 0 29 192 -3 132 17 47 130 21 15 134 47 24 127 37 13 129 18 17 34 0 0 8 17 55 30 190 -1 130 17 42 128 17 34 132 51 14 125 27 32 Uncertainty in time = +/- 2 secs Prediction of 2012 Nov 16.0 Data for the target star ------------------------ * name: TYC 6896-00287-1 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 20 05 31.5899 DE: -25 15 02.776 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .024, .035 ) * V mag [mag]: 10.4 * B mag [mag]: 10.9 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (267) Tirza approx. diameter [km]: 56 approx. diameter ["]: .027 distance from Earth [AU]: 2.88200 * orbital information: orbit source: Preston date of fit: 2012 Sep 26 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1105 number of rejected observations: 43 time covered by the observations: 1907 Nov 07 - 2012 Sep 18 1 sigma uncertainty ellipse (major, minor, PA): 0.016, 0.009, 82° remarks: * orbital elements for (267) Tirza : Mean anomaly = 40.39027929 deg Arg. of pericenter = 195.68434709 deg Long. of node = 73.89502733 deg Inclination = 6.00967644 deg Eccentricity = 0.10117797 Semimajor axis = 2.77341740 AU Perihelion dist = 2.49280865 AU Mag: H = 10.08, G = 0.15 Epoch of elements : MJD 56249.34500000 TDT (2012 Nov 18.345) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Nov 18 267 Tirza 8h 16.8m UT 10.4 20 5 31.590-25 15 2.78TYC 6896-00287-1 10.9 15.8 56 1.7 2.882 4.068 13.11 119.3922 -25.254 52.11 -19.35 8.2805 -0.18325 0.77349 18.08946 4.29709 0.00507 0.00084 2000 38.396117201211 9.00000195.684347 73.895027 6.0096760.10117797 2.7734174 2.492808710.5 5.00.15 RATE 2.1339350 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.037 0.029 360 2.34 0.036 0 0-1 4 056247.0020121118_0287-1 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 26, 22:55 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org