IOTA/IOTA-ES occultation update for (856) Backlunda / UCAC4 340-164364 event on 2023 Sep 18, 03:13 UT Visible from S USA, Mexico Summary ------- On 2023 Sep 18 UT, the 45.2 km diameter asteroid (856) Backlunda will occult a 12.4 mag star in the constellation Sagittarius for observers along a path across S USA, Mexico. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.89 mag to 15.25 mag (the magnitude of the asteroid) for at most 3.890 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 18, 03:07 - 2023 Sep 18, 03:18 * geocentric midpoint of event [JD]: 2460205.63412505 * magnitude of target star: 12.44 * magnitude drop [mag]: 2.89 * estimated maximum duration [s]: 3.890 * Moon: 9 % sunlit, 70° distance * Sun: 105° distance * rough path description: S USA, Mexico The occultation path -------------------- * approximate projected width [km]: 78 * 1 sigma uncertainty interval [path widths]: +/- 0.06 * 1 sigma uncertainty interval [seconds]: +/- 1.2 * 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]: 11.6149 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC4 340-164364 by 856 Backlunda on 2023 Sep 18 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 -157 0 0 .. .. .... .. .. .. .. .. .. 63 42 11 .. .. .. 63 37 35 .. .. .. .... -156 0 1 63 38 9 3 7 52.8 1 150 10 62 57 53 64 19 46 62 53 20 .. .. .. .... -155 0 1 62 52 52 3 7 53.1 2 151 9 62 12 59 63 34 4 62 8 28 63 38 53 -0.80 -154 0 1 62 7 1 3 7 53.5 2 152 9 61 27 32 62 47 47 61 23 4 62 52 33 -1.02 -153 0 1 61 20 40 3 7 54.3 3 153 9 60 41 36 62 0 58 60 37 11 62 5 41 -1.12 -152 0 1 60 33 53 3 7 55.2 4 154 8 59 55 15 61 13 42 59 50 52 61 18 22 -1.17 -151 0 1 59 46 41 3 7 56.5 5 154 8 59 8 29 60 26 2 59 4 10 60 30 38 -1.21 -150 0 1 58 59 10 3 7 58.0 6 155 8 58 21 24 59 38 1 58 17 8 59 42 34 -1.24 -149 0 1 58 11 21 3 7 59.8 7 156 7 57 34 4 58 49 43 57 29 50 58 54 12 -1.26 -148 0 1 57 23 21 3 8 1.8 8 157 7 56 46 30 58 1 12 56 42 19 58 5 38 -1.27 -147 0 1 56 35 10 3 8 4.2 9 158 6 55 58 46 57 12 31 55 54 39 57 16 53 -1.28 -146 0 1 55 46 52 3 8 6.8 10 159 6 55 10 57 56 23 44 55 6 52 56 28 2 -1.29 -145 0 1 54 58 32 3 8 9.7 11 160 5 54 23 4 55 34 54 54 19 3 55 39 8 -1.30 -144 0 1 54 10 12 3 8 13.0 12 161 5 53 35 12 54 46 4 53 31 13 54 50 15 -1.31 -143 0 1 53 21 55 3 8 16.5 13 161 4 52 47 22 53 57 17 52 43 26 54 1 25 -1.31 -142 0 1 52 33 44 3 8 20.3 14 162 4 51 59 38 53 8 37 51 55 46 53 12 41 -1.32 -141 0 1 51 45 42 3 8 24.4 15 163 3 51 12 4 52 20 7 51 8 14 52 24 8 -1.32 -140 0 1 50 57 53 3 8 28.8 16 164 2 50 24 41 51 31 49 50 20 54 51 35 46 -1.33 -139 0 1 50 10 18 3 8 33.5 17 165 2 49 37 32 50 43 46 49 33 49 50 47 40 -1.33 -138 0 1 49 23 1 3 8 38.5 17 166 1 48 50 41 49 56 2 48 47 0 49 59 53 -1.34 -137 0 1 48 36 4 3 8 43.7 18 167 0 48 4 9 49 8 38 48 0 31 49 12 25 -1.34 -136 0 1 47 49 29 3 8 49.2 19 168 0 47 17 59 48 21 37 47 14 23 48 25 21 -1.34 -135 0 1 47 3 19 3 8 55.0 20 169 -1 46 32 13 47 35 1 46 28 40 47 38 42 -1.35 -134 0 1 46 17 36 3 9 1.1 21 170 -2 45 46 53 46 48 52 45 43 23 46 52 30 -1.35 -133 0 1 45 32 21 3 9 7.4 22 171 -3 45 2 2 46 3 13 44 58 35 46 6 49 -1.35 -132 0 1 44 47 38 3 9 13.9 23 172 -3 44 17 42 45 18 6 44 14 17 45 21 39 -1.35 -131 0 1 44 3 28 3 9 20.7 24 173 -4 43 33 54 44 33 33 43 30 32 44 37 3 -1.36 -130 0 1 43 19 53 3 9 27.7 24 174 -5 42 50 40 43 49 35 42 47 20 43 53 2 -1.36 -129 0 1 42 36 54 3 9 34.9 25 175 -6 42 8 2 43 6 14 42 4 45 43 9 38 -1.36 -128 0 1 41 54 33 3 9 42.4 26 176 -7 41 26 2 42 23 31 41 22 47 42 26 53 -1.36 -127 0 1 41 12 52 3 9 50.0 27 177 -8 40 44 41 41 41 29 40 41 28 41 44 48 -1.37 -126 0 1 40 31 51 3 9 57.8 27 178 -8 40 4 0 41 0 8 40 0 49 41 3 26 -1.37 -125 0 1 39 51 34 3 10 5.8 28 179 -9 39 24 1 40 19 31 39 20 52 40 22 46 -1.37 -124 0 1 39 11 59 3 10 14.0 29 180 -10 38 44 45 39 39 37 38 41 38 39 42 50 -1.37 -123 0 1 38 33 9 3 10 22.3 29 181 -11 38 6 13 39 0 29 38 3 8 39 3 39 -1.38 -122 0 1 37 55 6 3 10 30.8 30 182 -12 37 28 26 38 22 7 37 25 23 38 25 15 -1.38 -121 0 1 37 17 48 3 10 39.4 31 183 -13 36 51 26 37 44 33 36 48 25 37 47 39 -1.38 -120 0 1 36 41 19 3 10 48.2 31 184 -14 36 15 13 37 7 47 36 12 14 37 10 51 -1.38 -119 0 1 36 5 38 3 10 57.0 32 186 -15 35 39 47 36 31 49 35 36 50 36 34 52 -1.39 -118 0 1 35 30 47 3 11 6.0 32 187 -16 35 5 11 35 56 42 35 2 15 35 59 43 -1.39 -117 0 1 34 56 45 3 11 15.0 33 188 -17 34 31 24 35 22 26 34 28 30 35 25 24 -1.39 -116 0 1 34 23 35 3 11 24.2 33 189 -18 33 58 28 34 49 0 33 55 35 34 51 57 -1.39 -115 0 1 33 51 15 3 11 33.4 33 190 -19 33 26 22 34 16 27 33 23 31 34 19 22 -1.39 -114 0 1 33 19 48 3 11 42.7 34 192 -20 32 55 7 33 44 45 32 52 18 33 47 39 -1.40 -113 0 1 32 49 12 3 11 52.0 34 193 -21 32 24 45 33 13 57 32 21 57 33 16 49 -1.40 -112 0 1 32 19 29 3 12 1.4 34 194 -22 31 55 14 32 44 1 31 52 28 32 46 52 -1.40 -111 0 1 31 50 40 3 12 10.8 35 195 -23 31 26 36 32 15 0 31 23 51 32 17 49 -1.40 -110 0 1 31 22 43 3 12 20.3 35 196 -24 30 58 51 31 46 52 30 56 7 31 49 39 -1.40 -109 0 1 30 55 41 3 12 29.8 35 198 -25 30 32 0 31 19 38 30 29 17 31 22 24 -1.40 -108 0 0 30 29 32 3 12 39.2 35 199 -26 30 6 1 30 53 18 30 3 20 30 56 4 -1.41 -107 0 0 30 4 18 3 12 48.7 35 200 -27 29 40 57 30 27 54 29 38 17 30 30 38 -1.41 -106 0 0 29 39 58 3 12 58.2 35 201 -28 29 16 47 30 3 24 29 14 8 30 6 7 -1.41 -105 0 0 29 16 33 3 13 7.6 35 203 -29 28 53 31 29 39 49 28 50 53 29 42 30 -1.41 -104 0 0 28 54 2 3 13 17.0 35 204 -30 28 31 9 29 17 9 28 28 31 29 19 49 -1.41 -103 0 0 28 32 26 3 13 26.4 35 205 -31 28 9 41 28 55 24 28 7 5 28 58 4 -1.41 -102 0 0 28 11 44 3 13 35.8 35 206 -32 27 49 8 28 34 35 27 46 33 28 37 13 -1.41 -101 0 0 27 51 58 3 13 45.0 35 207 -33 27 29 29 28 14 40 27 26 55 28 17 18 -1.42 -100 0 0 27 33 7 3 13 54.3 35 208 -34 27 10 45 27 55 42 27 8 11 27 58 18 -1.42 - 99 0 0 27 15 10 3 14 3.5 35 210 -35 26 52 55 27 37 38 26 50 23 27 40 14 -1.42 - 98 0 0 26 58 9 3 14 12.6 35 211 -35 26 36 0 27 20 30 26 33 28 27 23 5 -1.42 - 97 0 0 26 42 2 3 14 21.6 34 212 -36 26 20 0 27 4 16 26 17 28 27 6 51 -1.42 - 96 0 0 26 26 50 3 14 30.5 34 213 -37 26 4 54 26 48 59 26 2 23 26 51 32 -1.42 - 95 0 0 26 12 33 3 14 39.4 34 214 -38 25 50 42 26 34 36 25 48 12 26 37 9 -1.42 - 94 0 0 25 59 11 3 14 48.1 33 215 -39 25 37 25 26 21 8 25 34 55 26 23 41 -1.42 - 93 0 0 25 46 43 3 14 56.8 33 216 -40 25 25 2 26 8 35 25 22 33 26 11 7 -1.42 - 92 0 0 25 35 9 3 15 5.3 33 217 -41 25 13 33 25 56 58 25 11 5 25 59 29 -1.42 - 91 0 0 25 24 31 3 15 13.8 32 218 -42 25 2 58 25 46 15 25 0 30 25 48 45 -1.42 - 90 0 0 25 14 46 3 15 22.1 32 219 -43 24 53 18 25 36 26 24 50 50 25 38 57 -1.42 - 89 0 0 25 5 56 3 15 30.3 31 220 -44 24 44 31 25 27 33 24 42 4 25 30 3 -1.42 - 88 0 0 24 58 1 3 15 38.3 31 221 -45 24 36 39 25 19 34 24 34 12 25 22 4 -1.43 - 87 0 0 24 50 59 3 15 46.3 30 222 -46 24 29 40 25 12 29 24 27 14 25 14 59 -1.43 - 86 0 0 24 44 51 3 15 54.1 30 223 -46 24 23 35 25 6 19 24 21 9 25 8 48 -1.43 - 85 0 0 24 39 38 3 16 1.7 29 223 -47 24 18 23 25 1 3 24 15 58 25 3 32 -1.43 - 84 0 0 24 35 18 3 16 9.2 28 224 -48 24 14 5 24 56 41 24 11 40 24 59 10 -1.43 - 83 0 0 24 31 51 3 16 16.5 28 225 -49 24 10 41 24 53 13 24 8 15 24 55 42 -1.43 - 82 0 0 24 29 19 3 16 23.7 27 226 -50 24 8 9 24 50 39 24 5 44 24 53 7 -1.43 - 81 0 0 24 27 40 3 16 30.7 27 227 -50 24 6 31 24 48 59 24 4 6 24 51 27 -1.43 - 80 0 0 24 26 54 3 16 37.6 26 227 -51 24 5 46 24 48 13 24 3 21 24 50 41 -1.43 - 79 0 0 24 27 1 3 16 44.2 25 228 -52 24 5 54 24 48 20 24 3 28 24 50 48 -1.43 - 78 0 0 24 28 2 3 16 50.7 24 229 -53 24 6 54 24 49 20 24 4 29 24 51 48 -1.43 - 77 0 0 24 29 55 3 16 57.0 24 229 -53 24 8 48 24 51 14 24 6 22 24 53 42 -1.43 - 76 0 0 24 32 42 3 17 3.2 23 230 -54 24 11 34 24 54 1 24 9 8 24 56 29 -1.43 - 75 0 0 24 36 21 3 17 9.1 22 231 -55 24 15 12 24 57 41 24 12 47 25 0 9 -1.43 - 74 0 0 24 40 53 3 17 14.9 21 231 -55 24 19 43 25 2 14 24 17 17 25 4 43 -1.43 - 73 0 0 24 46 18 3 17 20.4 21 232 -56 24 25 6 25 7 40 24 22 40 25 10 9 -1.43 - 72 0 0 24 52 34 3 17 25.8 20 233 -56 24 31 21 25 13 59 24 28 55 25 16 28 -1.43 - 71 0 0 24 59 44 3 17 30.9 19 233 -57 24 38 28 25 21 10 24 36 2 25 23 39 -1.43 - 70 0 0 25 7 45 3 17 35.9 18 234 -57 24 46 27 25 29 14 24 44 1 25 31 43 -1.43 - 69 0 0 25 16 38 3 17 40.6 17 234 -58 24 55 18 25 38 10 24 52 51 25 40 40 -1.43 - 68 0 0 25 26 24 3 17 45.1 17 235 -58 25 5 0 25 47 59 25 2 33 25 50 28 -1.43 - 67 0 0 25 37 1 3 17 49.4 16 235 -58 25 15 34 25 58 39 25 13 7 26 1 9 -1.43 - 66 0 0 25 48 30 3 17 53.5 15 236 -59 25 26 59 26 10 12 25 24 32 26 12 42 -1.43 - 65 0 0 26 0 50 3 17 57.3 14 237 -59 25 39 16 26 22 36 25 36 48 26 25 7 -1.43 - 64 0 0 26 14 2 3 18 0.9 13 237 -59 25 52 24 26 35 52 25 49 55 26 38 24 -1.43 - 63 0 0 26 28 5 3 18 4.3 12 238 -59 26 6 23 26 50 0 26 3 53 26 52 32 -1.43 - 62 0 0 26 43 0 3 18 7.5 11 238 -59 26 21 12 27 5 0 26 18 42 27 7 32 -1.44 - 61 0 0 26 58 45 3 18 10.4 10 239 -60 26 36 52 27 20 50 26 34 22 27 23 24 -1.44 - 60 0 0 27 15 22 3 18 13.1 9 239 -60 26 53 23 27 37 32 26 50 52 27 40 6 -1.44 - 59 0 0 27 32 48 3 18 15.5 9 240 -60 27 10 44 27 55 5 27 8 13 27 57 40 -1.45 - 58 0 0 27 51 6 3 18 17.7 8 240 -59 27 28 56 28 13 29 27 26 23 28 16 4 -1.45 - 57 0 0 28 10 14 3 18 19.6 7 241 -59 27 47 57 28 32 43 27 45 24 28 35 20 -1.46 - 56 0 0 28 30 12 3 18 21.3 6 241 -59 28 7 48 28 52 48 28 5 14 28 55 25 -1.47 - 55 0 0 28 50 59 3 18 22.7 5 242 -59 28 28 29 29 13 44 28 25 54 29 16 21 -1.48 - 54 0 0 29 12 37 3 18 23.9 4 242 -59 28 49 59 29 35 29 28 47 23 29 38 8 -1.50 - 53 0 0 29 35 4 3 18 24.8 3 243 -58 29 12 18 29 58 4 29 9 41 30 0 44 -1.54 - 52 0 0 29 58 20 3 18 25.4 2 243 -58 29 35 26 30 21 28 29 32 48 30 24 9 -1.61 - 51 0 0 30 22 25 3 18 25.8 1 244 -58 29 59 22 30 45 42 29 56 44 30 48 24 -1.82 - 50 0 0 30 47 19 3 18 26.0 0 244 -57 30 24 7 .. .. .. 30 21 27 .. .. .. -11.15 Uncertainty in time = +/- 1 secs Prediction of 2023 Aug 27.0 Data for the target star ------------------------ * name: UCAC4 340-164364 * constellation : Sagittarius * BCRS position with proper motion to date of event [h,m,s ; °,',"] RA: 18 40 07.6042 DE: -22 09 10.284 * GCRS Astrometric position with proper motion and parallax to date of event [h,m,s ; °,',"] RA: 18 40 07.6042 DE: -22 09 10.284 * position source: Gaia DR3 * standard error: RA,DE [mas]: (0.200,0.200) * V mag [mag]: 12.4 * Diameter [mas]: 0.00 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (856) Backlunda asteroid class: approx. diameter [km]: 45 approx. diameter ["]: 0.031 distance from Earth [AU]: 2.01940 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", 100.66° remarks: * orbital elements for (856)Backlunda : Mean anomaly = 90.7273745904 deg Arg. of pericenter = 72.5918414106 deg Long. of node = 125.5321613256 deg Inclination = 14.3272070521 deg Eccentricity = 0.1191328616 Semimajor axis = 2.4348374652 AU Perihelion dist = 2.1447683104 AU Mag: H = 10.96, G = 0.15 Epoch of elements : MJD 60205.13416667 TDT (2023 Sep 18.1342) ------ occelmnt file for Occult BEGIN ----------------------------------- JPL#972023Aug24,3.89,2023,9,18,3.219001,0.295400,0.759445,6.109230,-2.378092,0.005401,0.000365,0.000000,0.000000 -124.6872,-22.1318,130.31,2.00,False UCAC4 340-164364,18.66877896,-22.1528566,0.00,12.44,0.00,0.0,4,,18.69251098,-22.1318273,2.89,0.00,0,0,0 856,Backlunda,15.25,45.200,2.0194,0,0,1.915,-10.35,,2.6,0 0,90.6926,2023,9,18,72.5918,125.5322,14.3272,0.11913,2.43484,2.14477,10.66,5.0,0.15 1.058,0.0093,0.0005,101,0.0093,Known errors,-1.00,0,-1,-1 20230918_164364,60182.99 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2023 Aug 26, 23:46 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 stevepr@acm.org