IOTA/IOTA-ES occultation update for (856) Backlunda / UCAC4 339-162137 event on 2023 Sep 20, 12:21 UT Visible from Japan, China Summary ------- On 2023 Sep 20 UT, the 45.2 km diameter asteroid (856) Backlunda will occult a 11.7 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 3.63 mag to 15.29 mag (the magnitude of the asteroid) for at most 3.640 seconds. This update is based on, astrometry for the asteroid kindly provided by the IAU Minor Planet Center. This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The event at a glimpse ---------------------- * Rank: 100 * date and approx. time of event: 2023 Sep 20, 12:17 - 2023 Sep 20, 12:25 * geocentric midpoint of event [JD]: 2460208.01493296 * magnitude of target star: 11.70 * magnitude drop [mag]: 3.63 * estimated maximum duration [s]: 3.640 * Moon: 27 % sunlit, 40° distance * Sun: 103° distance * rough path description: Japan, China The occultation path -------------------- * approximate projected width [km]: 96 * 1 sigma uncertainty interval [path widths]: +/- 0.05 * 1 sigma uncertainty interval [seconds]: +/- 1.1 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- 0.009, +/- 0.002) * 1 sigma uncertainty ellipse (major, minor, PA): (0.009", 0.000", 101°) * approx speed of asteroid's shadow [km/s]: 12.4264 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC4 339-162137 by 856 Backlunda on 2023 Sep 20 Centre Star Star Sun Path Limits Error Limits Alt E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " Latitude Latitude Latitude Latitude 74 0 0 .. .. .... .. .. .. .. .. .. 65 54 27 .. .. .. 65 48 2 .. .. .. .... 75 0 1 66 2 0 12 17 30.9 0 159 5 64 52 57 .. .. .. 64 46 50 .. .. .. .... 76 0 1 64 58 10 12 17 31.1 1 160 4 63 52 27 66 10 54 63 46 36 66 18 9 -0.82 77 0 0 63 55 40 12 17 31.8 2 161 4 62 52 55 65 4 25 62 47 18 65 11 14 -1.30 78 0 0 62 54 25 12 17 32.9 4 162 4 61 54 20 63 59 43 61 48 56 64 6 9 -1.48 79 0 0 61 54 23 12 17 34.3 5 163 3 60 56 41 62 56 38 60 51 29 63 2 44 -1.57 80 0 0 60 55 30 12 17 36.2 6 164 3 59 59 58 61 55 3 59 54 57 62 0 51 -1.63 81 0 0 59 57 43 12 17 38.4 7 165 2 59 4 10 60 54 50 58 59 18 61 0 24 -1.67 82 0 0 59 1 1 12 17 41.0 8 166 2 58 9 16 59 55 58 58 4 34 60 1 17 -1.69 83 0 0 58 5 23 12 17 43.9 9 167 1 57 15 18 58 58 21 57 10 44 59 3 28 -1.71 84 0 0 57 10 48 12 17 47.2 10 168 1 56 22 14 58 1 58 56 17 49 58 6 54 -1.73 85 0 0 56 17 14 12 17 50.8 11 168 0 55 30 6 57 6 45 55 25 48 57 11 31 -1.74 86 0 0 55 24 43 12 17 54.7 12 169 0 54 38 53 56 12 43 54 34 42 56 17 20 -1.75 87 0 0 54 33 13 12 17 58.9 13 170 -1 53 48 36 55 19 48 53 44 31 55 24 17 -1.76 88 0 0 53 42 43 12 18 3.4 14 171 -2 52 59 15 54 28 1 52 55 16 54 32 22 -1.77 89 0 0 52 53 15 12 18 8.2 15 172 -2 52 10 50 53 37 21 52 6 57 53 41 34 -1.78 90 0 0 52 4 47 12 18 13.2 16 173 -3 51 23 22 52 47 46 51 19 34 52 51 53 -1.79 91 0 0 51 17 20 12 18 18.5 16 174 -4 50 36 52 51 59 16 50 33 9 52 3 17 -1.79 92 0 0 50 30 54 12 18 24.0 17 175 -4 49 51 18 51 11 52 49 47 40 51 15 47 -1.80 93 0 0 49 45 29 12 18 29.8 18 176 -5 49 6 42 50 25 32 49 3 8 50 29 21 -1.80 94 0 0 49 1 4 12 18 35.8 19 177 -6 48 23 4 49 40 16 48 19 34 49 44 0 -1.81 95 0 0 48 17 41 12 18 42.0 20 178 -7 47 40 25 48 56 4 47 36 59 48 59 44 -1.81 96 0 0 47 35 18 12 18 48.4 20 179 -7 46 58 43 48 12 56 46 55 21 48 16 31 -1.82 97 0 0 46 53 56 12 18 55.0 21 180 -8 46 18 1 47 30 52 46 14 42 47 34 23 -1.82 98 0 0 46 13 36 12 19 1.7 22 181 -9 45 38 18 46 49 51 45 35 2 46 53 18 -1.82 99 0 0 45 34 17 12 19 8.6 22 182 -10 44 59 34 46 9 54 44 56 21 46 13 17 -1.83 100 0 0 44 55 59 12 19 15.7 23 183 -11 44 21 49 45 31 1 44 18 40 45 34 20 -1.83 101 0 0 44 18 42 12 19 22.9 23 184 -12 43 45 4 44 53 10 43 41 57 44 56 26 -1.83 102 0 0 43 42 27 12 19 30.2 24 185 -13 43 9 18 44 16 23 43 6 15 44 19 36 -1.84 103 0 0 43 7 13 12 19 37.7 24 186 -13 42 34 33 43 40 39 42 31 32 43 43 49 -1.84 104 0 0 42 33 1 12 19 45.2 25 187 -14 42 0 47 43 5 58 41 57 49 43 9 5 -1.84 105 0 0 41 59 50 12 19 52.9 25 188 -15 41 28 2 42 32 20 41 25 5 42 35 24 -1.85 106 0 0 41 27 40 12 20 0.6 26 190 -16 40 56 16 41 59 44 40 53 22 42 2 46 -1.85 107 0 0 40 56 32 12 20 8.4 26 191 -17 40 25 31 41 28 12 40 22 39 41 31 11 -1.85 108 0 0 40 26 25 12 20 16.3 27 192 -18 39 55 46 40 57 42 39 52 56 41 0 39 -1.86 109 0 0 39 57 19 12 20 24.2 27 193 -19 39 27 1 40 28 14 39 24 12 40 31 9 -1.86 110 0 0 39 29 15 12 20 32.2 27 194 -20 38 59 16 39 59 49 38 56 29 40 2 42 -1.86 111 0 0 39 2 12 12 20 40.2 27 195 -21 38 32 31 39 32 26 38 29 46 39 35 17 -1.86 112 0 0 38 36 9 12 20 48.3 28 196 -21 38 6 47 39 6 5 38 4 3 39 8 55 -1.87 113 0 0 38 11 8 12 20 56.3 28 197 -22 37 42 2 38 40 46 37 39 20 38 43 34 -1.87 114 0 0 37 47 8 12 21 4.4 28 198 -23 37 18 18 38 16 29 37 15 37 38 19 16 -1.87 115 0 0 37 24 9 12 21 12.5 28 200 -24 36 55 33 37 53 14 36 52 54 37 55 59 -1.87 116 0 0 37 2 10 12 21 20.5 28 201 -25 36 33 49 37 31 0 36 31 11 37 33 44 -1.88 117 0 0 36 41 11 12 21 28.6 28 202 -26 36 13 4 37 9 48 36 10 27 37 12 30 -1.88 118 0 0 36 21 13 12 21 36.6 28 203 -27 35 53 18 36 49 37 35 50 43 36 52 18 -1.88 119 0 0 36 2 16 12 21 44.6 28 204 -28 35 34 32 36 30 27 35 31 58 36 33 6 -1.88 120 0 0 35 44 18 12 21 52.5 28 205 -29 35 16 46 36 12 17 35 14 12 36 14 56 -1.88 121 0 0 35 27 20 12 22 0.4 28 206 -30 34 59 58 35 55 9 34 57 26 35 57 46 -1.88 122 0 0 35 11 23 12 22 8.3 28 207 -30 34 44 10 35 39 1 34 41 39 35 41 37 -1.89 123 0 0 34 56 24 12 22 16.0 27 208 -31 34 29 21 35 23 53 34 26 50 35 26 29 -1.89 124 0 0 34 42 26 12 22 23.8 27 209 -32 34 15 31 35 9 45 34 13 1 35 12 20 -1.89 125 0 0 34 29 26 12 22 31.4 27 210 -33 34 2 39 34 56 38 34 0 10 34 59 12 -1.89 126 0 0 34 17 26 12 22 38.9 27 211 -34 33 50 46 34 44 30 33 48 18 34 47 3 -1.89 127 0 0 34 6 25 12 22 46.4 26 212 -35 33 39 52 34 33 22 33 37 24 34 35 55 -1.89 128 0 0 33 56 23 12 22 53.8 26 213 -35 33 29 56 34 23 13 33 27 28 34 25 45 -1.89 129 0 0 33 47 19 12 23 1.0 26 214 -36 33 20 58 34 14 4 33 18 31 34 16 36 -1.89 130 0 0 33 39 14 12 23 8.2 25 215 -37 33 12 58 34 5 54 33 10 31 34 8 25 -1.90 131 0 0 33 32 8 12 23 15.3 25 216 -38 33 5 56 33 58 43 33 3 30 34 1 14 -1.90 132 0 0 33 26 0 12 23 22.2 25 217 -39 32 59 52 33 52 31 32 57 26 33 55 1 -1.90 133 0 0 33 20 50 12 23 29.0 24 218 -39 32 54 45 33 47 18 32 52 20 33 49 48 -1.90 134 0 0 33 16 38 12 23 35.6 24 219 -40 32 50 36 33 43 3 32 48 11 33 45 32 -1.90 135 0 0 33 13 24 12 23 42.2 23 220 -41 32 47 24 33 39 47 32 44 59 33 42 16 -1.90 136 0 0 33 11 8 12 23 48.6 23 220 -42 32 45 10 33 37 29 32 42 45 33 39 58 -1.90 137 0 0 33 9 49 12 23 54.8 22 221 -42 32 43 52 33 36 9 32 41 28 33 38 38 -1.90 138 0 0 33 9 28 12 24 0.9 22 222 -43 32 43 32 33 35 47 32 41 7 33 38 16 -1.90 139 0 0 33 10 5 12 24 6.8 21 223 -44 32 44 8 33 36 23 32 41 44 33 38 52 -1.90 140 0 0 33 11 38 12 24 12.6 20 224 -44 32 45 42 33 37 57 32 43 17 33 40 26 -1.90 141 0 0 33 14 10 12 24 18.2 20 224 -45 32 48 12 33 40 30 32 45 48 33 42 59 -1.90 142 0 0 33 17 39 12 24 23.6 19 225 -45 32 51 40 33 44 1 32 49 15 33 46 30 -1.90 143 0 0 33 22 4 12 24 28.9 18 226 -46 32 56 3 33 48 27 32 53 38 33 50 56 -1.90 144 0 0 33 27 26 12 24 34.0 18 227 -46 33 1 22 33 53 51 32 58 57 33 56 21 -1.90 145 0 0 33 33 44 12 24 38.8 17 227 -47 33 7 38 34 0 13 33 5 13 34 2 43 -1.90 146 0 0 33 41 0 12 24 43.5 16 228 -47 33 14 51 34 7 33 33 12 25 34 10 3 -1.90 147 0 0 33 49 13 12 24 48.0 16 229 -48 33 22 59 34 15 49 33 20 33 34 18 20 -1.90 148 0 0 33 58 22 12 24 52.3 15 229 -48 33 32 4 34 25 3 33 29 38 34 27 34 -1.90 149 0 0 34 8 28 12 24 56.4 14 230 -49 33 42 5 34 35 14 33 39 38 34 37 46 -1.91 150 0 0 34 19 30 12 25 0.3 13 231 -49 33 53 1 34 46 22 33 50 34 34 48 54 -1.91 151 0 0 34 31 28 12 25 4.0 13 231 -49 34 4 54 34 58 27 34 2 26 35 1 0 -1.91 152 0 0 34 44 23 12 25 7.5 12 232 -50 34 17 42 35 11 29 34 15 13 35 14 3 -1.91 153 0 0 34 58 15 12 25 10.7 11 233 -50 34 31 26 35 25 28 34 28 57 35 28 2 -1.91 154 0 0 35 13 2 12 25 13.7 10 233 -50 34 46 6 35 40 24 34 43 36 35 42 59 -1.92 155 0 0 35 28 46 12 25 16.5 9 234 -50 35 1 41 35 56 17 34 59 10 35 58 52 -1.92 156 0 0 35 45 26 12 25 19.1 9 235 -50 35 18 12 36 13 6 35 15 40 36 15 43 -1.92 157 0 0 36 3 2 12 25 21.4 8 235 -50 35 35 38 36 30 52 35 33 6 36 33 30 -1.93 158 0 0 36 21 34 12 25 23.5 7 236 -50 35 54 0 36 49 35 35 51 26 36 52 14 -1.94 159 0 0 36 41 2 12 25 25.3 6 237 -50 36 13 17 37 9 15 36 10 42 37 11 55 -1.95 160 0 0 37 1 26 12 25 26.9 5 237 -50 36 33 29 37 29 52 36 30 54 37 32 33 -1.96 161 0 0 37 22 46 12 25 28.3 4 238 -50 36 54 37 37 51 25 36 52 0 37 54 7 -1.98 162 0 0 37 45 2 12 25 29.4 3 238 -50 37 16 40 38 13 55 37 14 2 38 16 38 -2.01 163 0 0 38 8 14 12 25 30.2 3 239 -50 37 39 37 38 37 21 37 36 58 38 40 6 -2.06 164 0 0 38 32 22 12 25 30.8 2 240 -50 38 3 30 39 1 44 38 0 50 39 4 31 -2.17 165 0 0 38 57 25 12 25 31.1 1 240 -50 38 28 18 39 27 4 38 25 36 39 29 52 -2.54 166 0 0 .. .. .... .. .. .. .. .. .. 38 54 1 .. .. .. 38 51 17 .. .. .. .... Uncertainty in time = +/- 1 secs Prediction of 2023 Aug 27.0 Data for the target star ------------------------ * name: UCAC4 339-162137 * constellation : Sagittarius * BCRS position with proper motion to date of event [h,m,s ; °,',"] RA: 18 42 00.7688 DE: -22 18 49.158 * GCRS Astrometric position with proper motion and parallax to date of event [h,m,s ; °,',"] RA: 18 42 00.7687 DE: -22 18 49.158 * position source: Gaia DR3 * standard error: RA,DE [mas]: (0.200,0.100) * V mag [mag]: 11.7 * Diameter [mas]: 0.00 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (856) Backlunda asteroid class: approx. diameter [km]: 45 approx. diameter ["]: 0.030 distance from Earth [AU]: 2.05210 asteroid position offset in RA [mas]: 0 asteroid position offset in DE [mas]: 0 * orbital information: orbit source: JPL#97 date of fit: 2023 Aug 24 source of used astrometry: MPC, JPL number of used observations: 0 number of rejected observations: 0 time covered by the observations: 1800 Jan 01 - 1800 Jan 01 1 sigma uncertainty ellipse (major, minor, PA): 0.009", 0.000", 100.572° remarks: * orbital elements for (856)Backlunda : Mean anomaly = 91.3463415651 deg Arg. of pericenter = 72.5906090527 deg Long. of node = 125.5321579904 deg Inclination = 14.3272234340 deg Eccentricity = 0.1191324177 Semimajor axis = 2.4348312413 AU Perihelion dist = 2.1447639088 AU Mag: H = 10.96, G = 0.15 Epoch of elements : MJD 60207.51500000 TDT (2023 Sep 20.5150) ------ occelmnt file for Occult BEGIN ----------------------------------- JPL#972023Aug24,3.64,2023,9,20,12.358391,0.286113,0.833694,6.633771,-2.277367,0.005444,0.000395,0.000000,0.000000 96.3470,-22.2916,-6.99,1.07,False UCAC4 339-162137,18.70021358,-22.3136550,0.00,11.70,0.00,0.0,0,,18.72396001,-22.2915555,3.63,0.00,0,0,0 856,Backlunda,15.29,45.200,2.0521,0,0,2.049,-9.75,,2.6,0 0,91.2127,2023,9,20,72.5906,125.5322,14.3272,0.11913,2.43483,2.14476,10.66,5.0,0.15 1.047,0.0093,0.0004,101,0.0093,Known errors,-1.00,0,-1,-1 20230920_162137,60182.99 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2023 Aug 26, 23:47 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 stevepr@acm.org