IOTA/IOTA-ES occultation update for (2241) Alcathous / 2UCAC 20884374 event on 2009 Jun 30, 10:30 UT Visible from Pacific Ocean Summary ------- On 2009 Jun 30 UT, the 115 km diameter asteroid (2241) Alcathous will occult a 10.2 mag star in the constellation Scorpius for observers along a path across Pacific Ocean. In the case of an occultation, the combined light of the asteroid and the star will drop by 5.4 mag to 15.6 mag (the magnitude of the asteroid) for at most 8.7 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: 31 * date and approx. time of event: 2009 Jun 30, 10:22 - 2009 Jun 30, 10:35 UT * magnitude of target star: 10.2 * magnitude drop [mag]: 5.4 * estimated maximum duration [s]: 8.7 * Moon: 60 % sunlit, 48° distance * Sun: 150° distance * rough path description: Pacific Ocean The occultation path -------------------- * approximate projected width [km]: 136 * 1 sigma uncertainty interval [path widths]: +/- 2.13 * 1 sigma uncertainty interval [seconds]: +/- 25.4 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- .140 +/- .050) * 1 sigma uncertainty ellipse (major, minor, PA): ( .140", .050", 88° ) * approx speed of asteroid's shadow [km/s]: 13.2036 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of 2UCAC 20884374 by 2241 Alcathous on 2009 Jun 30 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 134 41 21 42 0 0 10 35 36 15 149 0 135 47 1 133 35 46 140 28 7 128 56 42 135 50 18 41 0 0 10 35 33 16 150 -1 136 55 5 134 45 38 141 32 39 130 10 40 136 58 30 40 0 0 10 35 29 17 151 -3 138 2 27 135 54 39 142 36 46 131 23 30 138 6 2 39 0 0 10 35 25 19 151 -4 139 9 15 137 2 58 143 40 33 132 35 19 139 13 1 38 0 0 10 35 21 20 152 -5 140 15 32 138 10 39 144 44 7 133 46 14 140 19 31 37 0 0 10 35 16 21 153 -6 141 21 25 139 17 48 145 47 30 134 56 21 141 25 39 36 0 0 10 35 11 22 154 -8 142 26 58 140 24 31 146 50 49 136 5 47 142 31 28 35 0 0 10 35 6 24 154 -9 143 32 17 141 30 53 147 54 6 137 14 37 143 37 5 34 0 0 10 35 1 25 155 -10 144 37 25 142 36 58 148 57 26 138 22 57 144 42 33 33 0 0 10 34 55 26 156 -12 145 42 28 143 42 52 150 0 54 139 30 52 145 47 56 32 0 0 10 34 49 28 157 -13 146 47 29 144 48 38 151 4 33 140 38 28 146 53 20 31 0 0 10 34 42 29 158 -14 147 52 34 145 54 22 152 8 27 141 45 48 147 58 48 30 0 0 10 34 36 30 158 -16 148 57 46 147 0 8 153 12 41 142 52 58 149 4 25 29 0 0 10 34 29 31 159 -17 150 3 9 148 5 59 154 17 19 144 0 2 150 10 14 28 0 0 10 34 22 33 160 -18 151 8 48 149 12 0 155 22 25 145 7 4 151 16 21 27 0 0 10 34 14 34 161 -20 152 14 47 150 18 15 156 28 3 146 14 9 152 22 48 26 0 0 10 34 6 35 162 -21 153 21 9 151 24 49 157 34 18 147 21 21 153 29 42 25 0 0 10 33 58 36 163 -22 154 28 0 152 31 46 158 41 14 148 28 45 154 37 5 24 0 0 10 33 50 38 164 -24 155 35 24 153 39 10 159 48 55 149 36 24 155 45 3 23 0 0 10 33 41 39 165 -25 156 43 25 154 47 5 160 57 28 150 44 23 156 53 39 22 0 0 10 33 32 40 166 -27 157 52 9 155 55 36 162 6 57 151 52 46 158 3 0 21 0 0 10 33 23 41 167 -28 159 1 39 157 4 49 163 17 27 153 1 38 159 13 9 20 0 0 10 33 13 43 168 -30 160 12 1 158 14 47 164 29 5 154 11 3 160 24 13 19 0 0 10 33 3 44 169 -31 161 23 22 159 25 36 165 41 57 155 21 6 161 36 16 18 0 0 10 32 53 45 170 -33 162 35 45 160 37 21 166 56 10 156 31 52 162 49 26 17 0 0 10 32 42 46 172 -34 163 49 18 161 50 8 168 11 51 157 43 26 164 3 47 16 0 0 10 32 31 47 173 -36 165 4 8 163 4 4 169 29 9 158 55 54 165 19 28 15 0 0 10 32 20 48 175 -37 166 20 21 164 19 15 170 48 12 160 9 20 166 36 35 14 0 0 10 32 9 49 176 -39 167 38 6 165 35 47 172 9 11 161 23 52 167 55 17 13 0 0 10 31 57 50 178 -40 168 57 30 166 53 50 173 32 17 162 39 35 169 15 43 12 0 0 10 31 44 51 180 -42 170 18 45 168 13 31 174 57 42 163 56 36 170 38 3 11 0 0 10 31 31 52 182 -43 171 41 59 169 35 0 176 25 42 165 15 4 172 2 28 10 0 0 10 31 18 53 184 -45 173 7 26 170 58 27 177 56 32 166 35 7 173 29 11 9 0 0 10 31 5 54 186 -47 174 35 19 172 24 5 179 30 31 167 56 52 174 58 25 8 0 0 10 30 51 55 188 -48 176 5 53 173 52 6 -178 51 57 169 20 32 176 30 28 7 0 0 10 30 36 56 191 -50 177 39 25 175 22 45 -177 10 27 170 46 16 178 5 37 6 0 0 10 30 21 56 193 -52 179 16 17 176 56 19 -175 24 25 172 14 17 179 44 15 5 0 0 10 30 6 57 196 -54 -179 3 8 178 33 10 -173 33 12 173 44 50 -178 33 11 4 0 0 10 29 50 57 199 -55 -177 18 19 -179 46 21 -171 35 59 175 18 11 -176 46 12 3 0 0 10 29 33 58 203 -57 -175 28 43 -178 1 43 -169 31 42 176 54 39 -174 54 7 2 0 0 10 29 16 58 206 -59 -173 33 36 -176 12 25 -167 18 57 178 34 35 -172 56 11 1 0 0 10 28 58 58 209 -61 -171 32 3 -174 17 44 -164 55 48 -179 41 34 -170 51 22 0 0 0 10 28 39 58 213 -63 -169 22 53 -172 16 47 -162 19 31 -177 53 18 Latitude Latitude Latitude Latitude -170 0 0 - 0 23 39 10 28 31 58 214 -64 0 16 51 - 1 3 49 3 13 20 - 3 51 38 -169 0 0 - 0 50 31 10 28 22 57 216 -64 - 0 10 13 - 1 30 29 2 45 17 - 4 17 27 -168 0 0 - 1 16 33 10 28 14 57 218 -65 - 0 36 28 - 1 56 19 2 18 6 - 4 42 29 -167 0 0 - 1 41 46 10 28 5 57 219 -66 - 1 1 53 - 2 21 20 1 51 47 - 5 6 43 -166 0 0 - 2 6 10 10 27 56 57 221 -67 - 1 26 29 - 2 45 33 1 26 18 - 5 30 11 -165 0 0 - 2 29 45 10 27 48 56 222 -68 - 1 50 15 - 3 8 57 1 1 41 - 5 52 51 -164 0 0 - 2 52 31 10 27 39 56 223 -68 - 2 13 12 - 3 31 33 0 37 55 - 6 14 44 -163 0 0 - 3 14 30 10 27 31 56 225 -69 - 2 35 21 - 3 53 21 0 15 0 - 6 35 52 -162 0 0 - 3 35 39 10 27 22 55 226 -70 - 2 56 40 - 4 14 21 - 0 7 6 - 6 56 12 -161 0 0 - 3 56 1 10 27 14 55 227 -70 - 3 17 12 - 4 34 33 - 0 28 20 - 7 15 47 -160 0 0 - 4 15 35 10 27 6 54 228 -71 - 3 36 55 - 4 53 58 - 0 48 45 - 7 34 35 -159 0 0 - 4 34 21 10 26 58 54 230 -71 - 3 55 50 - 5 12 36 - 1 8 20 - 7 52 38 -158 0 0 - 4 52 20 10 26 49 53 231 -72 - 4 13 57 - 5 30 26 - 1 27 5 - 8 9 55 -157 0 0 - 5 9 31 10 26 42 53 232 -72 - 4 31 16 - 5 47 30 - 1 45 1 - 8 26 27 -156 0 0 - 5 25 55 10 26 34 52 233 -72 - 4 47 48 - 6 3 46 - 2 2 8 - 8 42 13 -155 0 0 - 5 41 33 10 26 26 51 233 -72 - 5 3 33 - 6 19 17 - 2 18 25 - 8 57 15 -154 0 0 - 5 56 23 10 26 18 51 234 -73 - 5 18 30 - 6 34 1 - 2 33 54 - 9 11 31 -153 0 0 - 6 10 28 10 26 11 50 235 -73 - 5 32 41 - 6 47 58 - 2 48 34 - 9 25 3 -152 0 0 - 6 23 45 10 26 3 49 236 -73 - 5 46 5 - 7 1 10 - 3 2 26 - 9 37 51 -151 0 0 - 6 36 17 10 25 56 49 237 -73 - 5 58 42 - 7 13 36 - 3 15 29 - 9 49 54 -150 0 0 - 6 48 2 10 25 48 48 237 -73 - 6 10 33 - 7 25 16 - 3 27 44 -10 1 12 -149 0 0 - 6 59 2 10 25 41 47 238 -73 - 6 21 37 - 7 36 11 - 3 39 11 -10 11 47 -148 0 0 - 7 9 15 10 25 34 47 238 -72 - 6 31 56 - 7 46 20 - 3 49 50 -10 21 38 -147 0 0 - 7 18 43 10 25 27 46 239 -72 - 6 41 28 - 7 55 44 - 3 59 42 -10 30 44 -146 0 0 - 7 27 26 10 25 20 45 239 -72 - 6 50 14 - 8 4 22 - 4 8 45 -10 39 7 -145 0 0 - 7 35 23 10 25 14 44 240 -71 - 6 58 15 - 8 12 15 - 4 17 2 -10 46 47 -144 0 0 - 7 42 34 10 25 7 43 240 -71 - 7 5 29 - 8 19 24 - 4 24 30 -10 53 42 -143 0 0 - 7 49 0 10 25 0 43 241 -71 - 7 11 58 - 8 25 47 - 4 31 12 -10 59 54 -142 0 0 - 7 54 41 10 24 54 42 241 -70 - 7 17 41 - 8 31 26 - 4 37 6 -11 5 23 -141 0 0 - 7 59 36 10 24 47 41 241 -70 - 7 22 39 - 8 36 19 - 4 42 13 -11 10 8 -140 0 0 - 8 3 47 10 24 41 40 242 -69 - 7 26 51 - 8 40 28 - 4 46 32 -11 14 10 -139 0 0 - 8 7 12 10 24 35 39 242 -68 - 7 30 17 - 8 43 52 - 4 50 4 -11 17 29 -138 0 0 - 8 9 52 10 24 29 39 242 -68 - 7 32 58 - 8 46 31 - 4 52 49 -11 20 4 -137 0 0 - 8 11 46 10 24 23 38 243 -67 - 7 34 53 - 8 48 25 - 4 54 47 -11 21 56 -136 0 0 - 8 12 56 10 24 17 37 243 -66 - 7 36 3 - 8 49 34 - 4 55 58 -11 23 4 -135 0 0 - 8 13 20 10 24 11 36 243 -66 - 7 36 27 - 8 49 58 - 4 56 21 -11 23 29 -134 0 0 - 8 12 59 10 24 6 35 243 -65 - 7 36 5 - 8 49 38 - 4 55 56 -11 23 10 -133 0 0 - 8 11 52 10 24 0 34 243 -64 - 7 34 58 - 8 48 32 - 4 54 44 -11 22 8 -132 0 0 - 8 10 0 10 23 55 33 243 -63 - 7 33 4 - 8 46 41 - 4 52 45 -11 20 23 -131 0 0 - 8 7 22 10 23 50 33 244 -62 - 7 30 25 - 8 44 5 - 4 49 58 -11 17 53 -130 0 0 - 8 3 59 10 23 45 32 244 -62 - 7 26 59 - 8 40 43 - 4 46 23 -11 14 40 -129 0 0 - 7 59 49 10 23 40 31 244 -61 - 7 22 47 - 8 36 36 - 4 42 0 -11 10 42 -128 0 0 - 7 54 54 10 23 35 30 244 -60 - 7 17 49 - 8 31 44 - 4 36 49 -11 6 1 -127 0 0 - 7 49 12 10 23 30 29 244 -59 - 7 12 4 - 8 26 5 - 4 30 49 -11 0 35 -126 0 0 - 7 42 44 10 23 25 28 244 -58 - 7 5 33 - 8 19 41 - 4 24 1 -10 54 25 -125 0 0 - 7 35 30 10 23 21 27 244 -57 - 6 58 14 - 8 12 30 - 4 16 25 -10 47 30 -124 0 0 - 7 27 29 10 23 16 26 244 -56 - 6 50 9 - 8 4 33 - 4 7 59 -10 39 50 -123 0 0 - 7 18 40 10 23 12 25 244 -56 - 6 41 15 - 7 55 50 - 3 58 44 -10 31 26 -122 0 0 - 7 9 5 10 23 8 24 244 -55 - 6 31 35 - 7 46 19 - 3 48 40 -10 22 16 -121 0 0 - 6 58 42 10 23 4 23 244 -54 - 6 21 6 - 7 36 2 - 3 37 46 -10 12 20 -120 0 0 - 6 47 31 10 23 0 22 244 -53 - 6 9 49 - 7 24 57 - 3 26 1 -10 1 39 -119 0 0 - 6 35 32 10 22 57 21 244 -52 - 5 57 44 - 7 13 4 - 3 13 27 - 9 50 12 -118 0 0 - 6 22 45 10 22 53 20 244 -51 - 5 44 50 - 7 0 24 - 3 0 2 - 9 37 59 -117 0 0 - 6 9 9 10 22 50 19 244 -50 - 5 31 7 - 6 46 55 - 2 45 45 - 9 24 59 -116 0 0 - 5 54 44 10 22 46 18 244 -49 - 5 16 34 - 6 32 38 - 2 30 38 - 9 11 12 -115 0 0 - 5 39 30 10 22 43 17 244 -48 - 5 1 12 - 6 17 32 - 2 14 39 - 8 56 37 -114 0 0 - 5 23 26 10 22 40 16 244 -47 - 4 45 0 - 6 1 36 - 1 57 47 - 8 41 16 -113 0 0 - 5 6 33 10 22 37 15 244 -46 - 4 27 57 - 5 44 51 - 1 40 4 - 8 25 6 -112 0 0 - 4 48 49 10 22 35 14 244 -45 - 4 10 3 - 5 27 16 - 1 21 27 - 8 8 9 -111 0 0 - 4 30 14 10 22 32 13 244 -44 - 3 51 18 - 5 8 51 - 1 1 57 - 7 50 22 -110 0 0 - 4 10 48 10 22 30 12 244 -43 - 3 31 42 - 4 49 35 - 0 41 33 - 7 31 47 -109 0 0 - 3 50 30 10 22 28 11 244 -42 - 3 11 14 - 4 29 28 - 0 20 16 - 7 12 23 -108 0 0 - 3 29 21 10 22 26 10 244 -41 - 2 49 53 - 4 8 30 0 1 57 - 6 52 8 -107 0 0 - 3 7 19 10 22 24 9 244 -40 - 2 27 39 - 3 46 40 0 25 4 - 6 31 4 -106 0 0 - 2 44 24 10 22 22 8 244 -39 - 2 4 33 - 3 23 57 0 49 6 .. .. .. -105 0 0 - 2 20 37 10 22 21 7 243 -38 - 1 40 32 - 3 0 22 1 14 5 .. .. .. -104 0 0 - 1 55 56 10 22 20 6 243 -37 - 1 15 38 - 2 35 54 1 39 59 .. .. .. -103 0 0 - 1 30 21 10 22 19 5 243 -35 - 0 49 50 - 2 10 32 2 6 50 .. .. .. -102 0 0 - 1 3 52 10 22 18 4 243 -34 - 0 23 6 - 1 44 17 2 34 39 .. .. .. -101 0 0 - 0 36 28 10 22 17 3 243 -33 0 4 32 - 1 17 7 3 3 25 .. .. .. -100 0 0 - 0 8 9 10 22 17 2 243 -32 0 33 7 - 0 49 3 3 33 8 .. .. .. - 99 0 0 0 21 6 10 22 17 1 243 -31 1 2 37 - 0 20 4 .. .. .. .. .. .. Uncertainty in time = +/- 31 secs Prediction of 2009 Jun 24.0 Data for the target star ------------------------ * name: 2UCAC 20884374 * constellation : Scorpius * J2000 position with proper motion to date of event [h,m,s ; °,',"] RA: 16 23 38.4588 DE: -26 33 19.344 * position source: mpos:UCAC2 pm:UCAC2 * standard error: RA,DE ["]: ( .118, .023 ) * V mag [mag]: 10.2 * B mag [mag]: 0.0 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (2241) Alcathous approx. diameter [km]: 115 approx. diameter ["]: .039 distance from Earth [AU]: 4.08100 * orbital information: orbit source: Preston date of fit: 2009 Jun 24 source of used astrometry: FASTT MPC (via Astdys) number of used observations: 614 number of rejected observations: 13 time covered by the observations: 1950 Jun 19 - 2009 Jun 12 1 sigma uncertainty ellipse (major, minor, PA): 0.076, 0.044, 83° remarks: * orbital elements for (2241) Alcathous : Mean anomaly = 47.77065348 deg Arg. of pericenter = 292.14533230 deg Long. of node = 267.98078202 deg Inclination = 16.60752557 deg Eccentricity = 0.06618108 Semimajor axis = 5.20164516 AU Perihelion dist = 4.85739466 AU Mag: H = 8.64, G = 0.15 Epoch of elements : MJD 55012.43800000 TDT (2009 Jun 30.438) ------ occelmnt file for Occult BEGIN ----------------------------------- 2009 Jun 30 2241 Alcathous 10h 29.1m UT 10.2 16 23 38.459-26 33 19.342UCAC 20884374 0.0 15.6 115 8.7 4.081 -1.022 8.34 170.0085 -26.557 23.65 23.15 10.4850 0.27563 0.45242 -6.36854 3.87058 0.00296 -0.00005 2000 47.5681062009 628.00000292.145332267.980782 16.6075260.06618108 5.2016452 4.8573947 8.6 5.00.15 RATE 0.8307930 0.000000 0.000000 0.000000 0.0000000 0.0000000 0.0000000 Meas 0.140 0.050 88 3.13 0.083 0 55006.0020090630_884374 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2009 Jun 24, 16:53 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 425-688-9965 mailto: stevepr@acm.org