IOTA/IOTA-ES occultation update for (20) Massalia / 2UCAC 22999834 event on 2012 Oct 09, 10:45 UT Visible from Japan, China Summary ------- On 2012 Oct 09 UT, the 132 km diameter asteroid (20) Massalia will occult a 12.5 mag star in the constellation Sagittarius for observers along a path across Japan, China. In the case of an occultation, the combined light of the asteroid and the star will drop by 0.4 mag to 11.7 mag (the magnitude of the asteroid) for at most 7.4 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: 95 * date and approx. time of event: 2012 Oct 09, 10:45 - 2012 Oct 09, 10:49 UT * geocentric midpoint of event [JD]: 2456209.94838333 * magnitude of target star: 12.5 * magnitude drop [mag]: 0.4 * estimated maximum duration [s]: 7.4 * Moon: 38 % sunlit, 162° distance * Sun: 86° distance * rough path description: Japan, China The occultation path -------------------- * approximate projected width [km]: 204 * 1 sigma uncertainty interval [path widths]: +/- 0.43 * 1 sigma uncertainty interval [seconds]: +/- 5.5 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .057 +/- .030) * 1 sigma uncertainty ellipse (major, minor, PA): ( .057", .030", 90° ) * approx speed of asteroid's shadow [km/s]: 17.8157 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 22999834 by 20 Massalia on 2012 Oct 9 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 102 0 0 27 42 54 10 45 50 40 178 0 26 47 47 28 39 5 26 1 11 29 28 18 103 0 0 27 48 32 10 45 55 40 179 -1 26 53 21 28 44 46 26 6 42 29 34 3 104 0 0 27 54 43 10 46 1 40 180 -2 26 59 29 28 51 2 26 12 47 29 40 23 105 0 0 28 1 30 10 46 7 40 182 -3 27 6 11 28 57 53 26 19 26 29 47 17 106 0 0 28 8 50 10 46 12 40 183 -4 27 13 27 29 5 18 26 26 38 29 54 47 107 0 0 28 16 44 10 46 18 40 184 -5 27 21 17 29 13 17 26 34 23 30 2 51 108 0 0 28 25 13 10 46 24 39 185 -6 27 29 40 29 21 51 26 42 42 30 11 29 109 0 0 28 34 15 10 46 29 39 187 -6 27 38 36 29 30 59 26 51 34 30 20 43 110 0 0 28 43 50 10 46 35 39 188 -7 27 48 6 29 40 40 27 0 59 30 30 30 111 0 0 28 53 59 10 46 40 39 189 -8 27 58 9 29 50 56 27 10 57 30 40 51 112 0 0 29 4 41 10 46 46 38 190 -9 28 8 45 30 1 45 27 21 28 30 51 47 113 0 0 29 15 57 10 46 51 38 191 -10 28 19 53 30 13 7 27 32 30 31 3 16 114 0 0 29 27 44 10 46 57 38 192 -11 28 31 34 30 25 3 27 44 5 31 15 18 115 0 0 29 40 5 10 47 2 37 194 -12 28 43 47 30 37 31 27 56 12 31 27 53 116 0 0 29 52 57 10 47 7 37 195 -13 28 56 32 30 50 32 28 8 51 31 41 2 117 0 0 30 6 22 10 47 13 36 196 -14 29 9 48 31 4 5 28 22 1 31 54 43 118 0 0 30 20 18 10 47 18 36 197 -15 29 23 36 31 18 10 28 35 42 32 8 56 119 0 0 30 34 46 10 47 23 35 198 -15 29 37 55 31 32 47 28 49 54 32 23 41 120 0 0 30 49 45 10 47 28 35 199 -16 29 52 45 31 47 56 29 4 37 32 38 58 121 0 0 31 5 15 10 47 33 34 200 -17 30 8 6 32 3 35 29 19 50 32 54 46 122 0 0 31 21 15 10 47 38 34 201 -18 30 23 56 32 19 45 29 35 33 33 11 6 123 0 0 31 37 44 10 47 43 33 202 -19 30 40 16 32 36 25 29 51 45 33 27 55 124 0 0 31 54 44 10 47 48 33 203 -20 30 57 6 32 53 35 30 8 26 33 45 15 125 0 0 32 12 13 10 47 52 32 204 -21 31 14 24 33 11 15 30 25 36 34 3 5 126 0 0 32 30 10 10 47 57 31 205 -21 31 32 11 33 29 24 30 43 15 34 21 24 127 0 0 32 48 36 10 48 1 31 206 -22 31 50 26 33 48 1 31 1 21 34 40 12 128 0 0 33 7 30 10 48 6 30 207 -23 32 9 9 34 7 6 31 19 55 34 59 28 129 0 0 33 26 51 10 48 10 29 208 -24 32 28 19 34 26 39 31 38 55 35 19 12 130 0 0 33 46 38 10 48 14 29 209 -25 32 47 55 34 46 39 31 58 23 35 39 23 131 0 0 34 6 53 10 48 19 28 209 -25 33 7 58 35 7 6 32 18 16 36 0 1 132 0 0 34 27 32 10 48 23 27 210 -26 33 28 26 35 27 58 32 38 34 36 21 5 133 0 0 34 48 37 10 48 27 27 211 -27 33 49 19 35 49 16 32 59 17 36 42 35 134 0 0 35 10 7 10 48 30 26 212 -28 34 10 36 36 10 59 33 20 25 37 4 29 135 0 0 35 32 1 10 48 34 25 213 -28 34 32 17 36 33 6 33 41 56 37 26 48 136 0 0 35 54 18 10 48 38 24 214 -29 34 54 22 36 55 36 34 3 51 37 49 31 137 0 0 36 16 57 10 48 41 23 214 -30 35 16 49 37 18 29 34 26 7 38 12 36 138 0 0 36 39 59 10 48 45 23 215 -30 35 39 38 37 41 44 34 48 46 38 36 4 139 0 0 37 3 22 10 48 48 22 216 -31 36 2 48 38 5 21 35 11 45 38 59 54 140 0 0 37 27 5 10 48 51 21 217 -32 36 26 18 38 29 18 35 35 6 39 24 4 141 0 0 37 51 8 10 48 54 20 218 -32 36 50 8 38 53 36 35 58 45 39 48 34 142 0 0 38 15 31 10 48 57 19 218 -33 37 14 18 39 18 12 36 22 44 40 13 23 143 0 0 38 40 11 10 49 0 19 219 -34 37 38 45 39 43 7 36 47 1 40 38 31 144 0 0 39 5 9 10 49 3 18 220 -34 38 3 30 40 8 19 37 11 35 41 3 56 145 0 0 39 30 24 10 49 5 17 221 -35 38 28 32 40 33 48 37 36 26 41 29 38 146 0 0 39 55 55 10 49 8 16 221 -35 38 53 49 40 59 33 38 1 33 41 55 36 147 0 0 40 21 40 10 49 10 15 222 -36 39 19 22 41 25 32 38 26 55 42 21 49 148 0 0 40 47 40 10 49 12 15 223 -36 39 45 8 41 51 46 38 52 31 42 48 16 149 0 0 41 13 53 10 49 14 14 223 -37 40 11 8 42 18 13 39 18 21 43 14 56 150 0 0 41 40 18 10 49 16 13 224 -37 40 37 20 42 44 52 39 44 22 43 41 48 151 0 0 42 6 55 10 49 18 12 225 -38 41 3 44 43 11 43 40 10 36 44 8 52 152 0 0 42 33 42 10 49 20 11 226 -38 41 30 19 43 38 44 40 37 0 44 36 5 153 0 0 43 0 39 10 49 21 10 226 -38 41 57 3 44 5 54 41 3 34 45 3 28 154 0 0 43 27 44 10 49 23 9 227 -39 42 23 56 44 33 13 41 30 17 45 31 0 155 0 0 43 54 57 10 49 24 9 228 -39 42 50 56 45 0 39 41 57 8 45 58 38 156 0 0 44 22 16 10 49 25 8 229 -39 43 18 4 45 28 11 42 24 6 46 26 23 157 0 0 44 49 42 10 49 26 7 229 -40 43 45 17 45 55 50 42 51 10 46 54 13 158 0 0 45 17 12 10 49 27 6 230 -40 44 12 36 46 23 32 43 18 20 47 22 7 159 0 0 45 44 45 10 49 28 5 231 -40 44 39 59 46 51 18 43 45 33 47 50 5 160 0 0 46 12 22 10 49 29 4 231 -41 45 7 24 47 19 7 44 12 50 48 18 4 161 0 0 46 40 0 10 49 29 4 232 -41 45 34 52 47 46 57 44 40 9 48 46 5 162 0 0 47 7 40 10 49 29 3 233 -41 46 2 21 48 14 47 45 7 30 49 14 6 163 0 0 47 35 19 10 49 30 2 234 -41 46 29 50 48 42 37 .. .. .. 49 42 6 164 0 0 48 2 57 10 49 30 1 234 -41 46 57 18 49 10 25 .. .. .. .. .. .. 165 0 0 48 30 32 10 49 30 0 235 -41 47 24 45 .. .. .. .. .. .. .. .. .. Uncertainty in time = +/- 6 secs Prediction of 2012 Sep 27.0 Data for the target star ------------------------ * name: 2UCAC 22999834 * constellation : Sagittarius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 18 53 45.0202 DE: -22 07 39.054 * position source: mpos:UCAC4 pm:UCAC4 * standard error: RA,DE ["]: ( .056, .029 ) * V mag [mag]: 12.5 * B mag [mag]: 0.0 * Diameter [mas]: 0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (20) Massalia approx. diameter [km]: 132 approx. diameter ["]: .070 distance from Earth [AU]: 2.60100 * orbital information: orbit source: Preston date of fit: 2012 Sep 26 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 1539 number of rejected observations: 254 time covered by the observations: 1900 Jul 17 - 2012 Sep 21 1 sigma uncertainty ellipse (major, minor, PA): 0.007, 0.006, 84° remarks: * orbital elements for (20) Massalia : Mean anomaly = 207.43411371 deg Arg. of pericenter = 256.75404552 deg Long. of node = 206.19596312 deg Inclination = 0.70819032 deg Eccentricity = 0.14246264 Semimajor axis = 2.40887467 AU Perihelion dist = 2.06570002 AU Mag: H = 6.49, G = 0.25 Epoch of elements : MJD 56209.44800000 TDT (2012 Oct 09.448) ------ occelmnt file for Occult BEGIN ----------------------------------- 2012 Oct 9 20 Massalia 10h 45.7m UT 12.5 18 53 45.020-22 7 39.052UCAC 22999834 0.0 11.7 132 7.4 2.601 2.440 2.52 103.5620 -22.127 15.38 -6.51 10.7612 -0.05293 0.75963 10.02808 0.74422 0.00571 0.00054 2000 204.9434072012 930.00000256.754046206.195963 0.7081900.14246264 2.4088747 2.0657000 6.5 5.00.25 RATE 2.6362270 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.057 0.030 90 1.43 0.030 0 0 2-4 056197.0020121009_999834 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2012 Sep 26, 22:08 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org