IOTA/IOTA-ES occultation update for (149) Medusa / UCAC4 551-042106 event on 2021 Feb 04, 10:16 UT Visible from Australia Summary ------- On 2021 Feb 04 UT, the 22.4 km diameter asteroid (149) Medusa will occult a 10.9 mag star in the constellation Gemini for observers along a path across Australia. In the case of an occultation, the combined light of the asteroid and the star will drop by 2.33 mag to 13.09 mag (the magnitude of the asteroid) for at most 2.8 seconds. This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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: 87 * date and approx. time of event: 2021 Feb 04, 10:08 - 2021 Feb 04, 10:25 * geocentric midpoint of event [JD]: 2459249.92834583 * magnitude of target star: 10.90 * magnitude drop [mag]: 2.33 * estimated maximum duration [s]: 2.8 * Moon: 54 % sunlit, 105° distance * Sun: 160° distance * rough path description: Australia The occultation path -------------------- * approximate projected width [km]: 36 * 1 sigma uncertainty interval [path widths]: +/- 0.57 * 1 sigma uncertainty interval [seconds]: +/- 3.6 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- 0.034, +/- 0.016) * 1 sigma uncertainty ellipse (major, minor, PA): (0.034", 0.015", 100°) * approx speed of asteroid's shadow [km/s]: 8.0032 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of UCAC4 551-042106 by 149 Medusa on 2021 Feb 4 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 ' " Longitude Longitude Longitude Longitude .. .. .. -59 0 0 .. .. .... .. .. .. ... .. .. ... .. .. ... .. .. -116 13 43 .... -117 22 15 -58 0 0 10 8 37.0 1 312 -12 -116 53 49 -117 50 42 -116 21 10 -118 23 25 .... -119 30 34 -57 0 0 10 8 38.1 3 314 -13 -119 2 48 -119 58 23 -118 30 55 -120 30 21 0.85 Latitude Latitude Latitude Latitude -121 0 0 -56 17 29 10 8 39.5 4 316 -14 -56 4 26 -56 30 37 -55 49 32 -56 45 49 1.05 -122 0 0 -55 48 40 10 8 40.7 5 316 -15 -55 35 38 -56 1 47 -55 20 46 -56 16 57 1.14 -123 0 0 -55 19 38 10 8 42.1 5 317 -15 -55 6 38 -55 32 43 -54 51 48 -55 47 52 1.16 -124 0 0 -54 50 25 10 8 43.7 6 318 -16 -54 37 26 -55 3 28 -54 22 38 -55 18 34 1.18 -125 0 0 -54 21 0 10 8 45.6 7 319 -17 -54 8 4 -54 34 2 -53 53 18 -54 49 6 1.19 -126 0 0 -53 51 27 10 8 47.7 8 320 -18 -53 38 32 -54 4 26 -53 23 49 -54 19 27 1.20 -127 0 0 -53 21 45 10 8 50.1 8 320 -18 -53 8 52 -53 34 42 -52 54 11 -53 49 40 1.21 -128 0 0 -52 51 55 10 8 52.7 9 321 -19 -52 39 6 -53 4 50 -52 24 27 -53 19 46 1.22 -129 0 0 -52 22 0 10 8 55.5 10 322 -20 -52 9 13 -52 34 52 -51 54 37 -52 49 45 1.22 -130 0 0 -51 52 0 10 8 58.6 11 323 -20 -51 39 16 -52 4 49 -51 24 43 -52 19 39 1.23 -131 0 0 -51 21 56 10 9 2.0 11 324 -21 -51 9 15 -51 34 43 -50 54 45 -51 49 29 1.24 -132 0 0 -50 51 50 10 9 5.6 12 325 -22 -50 39 11 -51 4 34 -50 24 45 -51 19 17 1.24 -133 0 0 -50 21 43 10 9 9.5 13 325 -22 -50 9 7 -50 34 23 -49 54 44 -50 49 2 1.24 -134 0 0 -49 51 35 10 9 13.6 14 326 -23 -49 39 2 -50 4 12 -49 24 43 -50 18 48 1.25 -135 0 0 -49 21 29 10 9 18.0 14 327 -24 -49 8 59 -49 34 3 -48 54 43 -49 48 35 1.25 -136 0 0 -48 51 24 10 9 22.7 15 328 -24 -48 38 58 -49 3 55 -48 24 46 -49 18 23 1.25 -137 0 0 -48 21 24 10 9 27.6 16 329 -25 -48 9 1 -48 33 51 -47 54 52 -48 48 15 1.25 -138 0 0 -47 51 27 10 9 32.8 17 329 -25 -47 39 8 -48 3 51 -47 25 3 -48 18 11 1.26 -139 0 0 -47 21 36 10 9 38.2 18 330 -26 -47 9 20 -47 33 57 -46 55 20 -47 48 13 1.26 -140 0 0 -46 51 52 10 9 43.9 18 331 -27 -46 39 40 -47 4 9 -46 25 43 -47 18 21 1.26 -141 0 0 -46 22 16 10 9 49.9 19 332 -27 -46 10 7 -46 34 29 -45 56 14 -46 48 37 1.26 -142 0 0 -45 52 49 10 9 56.1 20 333 -28 -45 40 43 -46 4 58 -45 26 54 -46 19 1 1.26 -143 0 0 -45 23 31 10 10 2.5 21 334 -28 -45 11 29 -45 35 37 -44 57 45 -45 49 36 1.26 -144 0 0 -44 54 25 10 10 9.2 21 334 -29 -44 42 26 -45 6 27 -44 28 46 -45 20 21 1.26 -145 0 0 -44 25 30 10 10 16.2 22 335 -30 -44 13 35 -44 37 28 -43 59 59 -44 51 19 1.27 -146 0 0 -43 56 48 10 10 23.4 23 336 -30 -43 44 57 -44 8 43 -43 31 24 -44 22 29 1.27 -147 0 0 -43 28 20 10 10 30.8 23 337 -31 -43 16 32 -43 40 11 -43 3 4 -43 53 52 1.27 -148 0 0 -43 0 6 10 10 38.4 24 338 -31 -42 48 22 -43 11 53 -42 34 58 -43 25 31 1.27 -149 0 0 -42 32 8 10 10 46.3 25 339 -32 -42 20 28 -42 43 52 -42 7 8 -42 57 25 1.27 -150 0 0 -42 4 26 10 10 54.4 26 340 -32 -41 52 49 -42 16 6 -41 39 34 -42 29 35 1.27 -151 0 0 -41 37 2 10 11 2.7 26 340 -32 -41 25 29 -41 48 38 -41 12 17 -42 2 3 1.27 -152 0 0 -41 9 55 10 11 11.3 27 341 -33 -40 58 25 -41 21 28 -40 45 18 -41 34 48 1.27 -153 0 0 -40 43 7 10 11 20.0 28 342 -33 -40 31 41 -40 54 36 -40 18 37 -41 7 53 1.27 -154 0 0 -40 16 38 10 11 28.9 28 343 -34 -40 5 16 -40 28 4 -39 52 16 -40 41 16 1.27 -155 0 0 -39 50 30 10 11 38.1 29 344 -34 -39 39 11 -40 1 52 -39 26 15 -40 15 0 1.27 -156 0 0 -39 24 43 10 11 47.4 29 345 -34 -39 13 27 -39 36 1 -39 0 35 -39 49 5 1.27 -157 0 0 -38 59 16 10 11 56.9 30 346 -35 -38 48 4 -39 10 32 -38 35 16 -39 23 32 1.27 -158 0 0 -38 34 12 10 12 6.6 31 347 -35 -38 23 4 -38 45 24 -38 10 19 -38 58 20 1.27 -159 0 0 -38 9 31 10 12 16.4 31 348 -35 -37 58 25 -38 20 40 -37 45 45 -38 33 32 1.27 -160 0 0 -37 45 13 10 12 26.4 32 349 -35 -37 34 10 -37 56 18 -37 21 33 -38 9 6 1.27 -161 0 0 -37 21 18 10 12 36.6 32 350 -36 -37 10 19 -37 32 21 -36 57 46 -37 45 5 1.27 -162 0 0 -36 57 48 10 12 46.9 33 351 -36 -36 46 52 -37 8 47 -36 34 22 -37 21 28 1.27 -163 0 0 -36 34 43 10 12 57.3 33 352 -36 -36 23 50 -36 45 39 -36 11 23 -36 58 16 1.27 -164 0 0 -36 12 3 10 13 7.9 34 353 -36 -36 1 13 -36 22 56 -35 48 50 -36 35 29 1.27 -165 0 0 -35 49 48 10 13 18.6 34 354 -36 -35 39 1 -36 0 38 -35 26 42 -36 13 8 1.27 -166 0 0 -35 28 0 10 13 29.5 35 355 -36 -35 17 16 -35 38 47 -35 5 0 -35 51 14 1.27 -167 0 0 -35 6 38 10 13 40.4 35 356 -36 -34 55 57 -35 17 23 -34 43 44 -35 29 46 1.27 -168 0 0 -34 45 44 10 13 51.5 35 357 -36 -34 35 5 -34 56 25 -34 22 55 -35 8 45 1.27 -169 0 0 -34 25 16 10 14 2.6 36 358 -36 -34 14 40 -34 35 55 -34 2 33 -34 48 12 1.27 -170 0 0 -34 5 16 10 14 13.8 36 360 -36 -33 54 43 -34 15 52 -33 42 39 -34 28 6 1.27 -171 0 0 -33 45 45 10 14 25.2 36 1 -36 -33 35 14 -33 56 18 -33 23 13 -34 8 29 1.27 -172 0 0 -33 26 41 10 14 36.6 37 2 -36 -33 16 13 -33 37 12 -33 4 15 -33 49 20 1.27 -173 0 0 -33 8 6 10 14 48.1 37 3 -36 -32 57 41 -33 18 35 -32 45 45 -33 30 40 1.27 -174 0 0 -32 50 0 10 14 59.6 37 4 -36 -32 39 37 -33 0 26 -32 27 44 -33 12 29 1.27 -175 0 0 -32 32 24 10 15 11.2 37 5 -36 -32 22 3 -32 42 47 -32 10 12 -32 54 47 1.26 -176 0 0 -32 15 16 10 15 22.9 38 6 -36 -32 4 58 -32 25 38 -31 53 10 -32 37 35 1.26 -177 0 0 -31 58 39 10 15 34.5 38 7 -36 -31 48 22 -32 8 58 -31 36 37 -32 20 52 1.26 -178 0 0 -31 42 31 10 15 46.3 38 9 -35 -31 32 17 -31 52 48 -31 20 33 -32 4 40 1.26 -179 0 0 -31 26 54 10 15 58.0 38 10 -35 -31 16 41 -31 37 9 -31 5 0 -31 48 58 1.26 -180 0 0 -31 11 47 10 16 9.8 38 11 -35 -31 1 36 -31 22 0 -30 49 57 -31 33 47 1.26 179 0 0 -30 57 10 10 16 21.6 38 12 -35 -30 47 1 -31 7 21 -30 35 25 -31 19 7 1.26 178 0 0 -30 43 4 10 16 33.4 38 13 -34 -30 32 57 -30 53 14 -30 21 23 -31 4 57 1.26 177 0 0 -30 29 30 10 16 45.2 38 14 -34 -30 19 24 -30 39 37 -30 7 52 -30 51 18 1.26 176 0 0 -30 16 26 10 16 57.0 38 16 -34 -30 6 22 -30 26 32 -29 54 51 -30 38 11 1.26 175 0 0 -30 3 54 10 17 8.8 38 17 -33 -29 53 51 -30 13 58 -29 42 22 -30 25 35 1.26 174 0 0 -29 51 53 10 17 20.6 38 18 -33 -29 41 52 -30 1 56 -29 30 25 -30 13 31 1.26 173 0 0 -29 40 23 10 17 32.4 38 19 -33 -29 30 24 -29 50 25 -29 18 58 -30 1 59 1.26 172 0 0 -29 29 26 10 17 44.1 38 20 -32 -29 19 28 -29 39 26 -29 8 4 -29 50 58 1.26 171 0 0 -29 19 0 10 17 55.8 38 21 -32 -29 9 3 -29 28 59 -28 57 41 -29 40 30 1.26 170 0 0 -29 9 7 10 18 7.5 38 22 -31 -28 59 11 -29 19 4 -28 47 50 -29 30 34 1.26 169 0 0 -28 59 45 10 18 19.1 38 23 -31 -28 49 51 -29 9 42 -28 38 31 -29 21 10 1.26 168 0 0 -28 50 56 10 18 30.6 37 25 -30 -28 41 3 -29 0 51 -28 29 44 -29 12 18 1.26 167 0 0 -28 42 39 10 18 42.1 37 26 -30 -28 32 47 -28 52 34 -28 21 29 -29 3 59 1.26 166 0 0 -28 34 55 10 18 53.5 37 27 -29 -28 25 3 -28 44 48 -28 13 47 -28 56 13 1.26 165 0 0 -28 27 43 10 19 4.9 37 28 -29 -28 17 53 -28 37 36 -28 6 37 -28 49 0 1.26 164 0 0 -28 21 4 10 19 16.2 36 29 -28 -28 11 14 -28 30 56 -27 59 59 -28 42 19 1.26 163 0 0 -28 14 58 10 19 27.4 36 30 -28 -28 5 9 -28 24 49 -27 53 55 -28 36 11 1.27 162 0 0 -28 9 25 10 19 38.5 36 31 -27 -27 59 36 -28 19 16 -27 48 23 -28 30 37 1.27 161 0 0 -28 4 25 10 19 49.5 35 32 -26 -27 54 37 -28 14 15 -27 43 24 -28 25 36 1.27 160 0 0 -27 59 58 10 20 0.4 35 33 -26 -27 50 10 -28 9 47 -27 38 58 -28 21 7 1.27 159 0 0 -27 56 4 10 20 11.2 35 34 -25 -27 46 16 -28 5 53 -27 35 4 -28 17 13 1.27 158 0 0 -27 52 43 10 20 21.9 34 35 -24 -27 42 56 -28 2 32 -27 31 44 -28 13 51 1.27 157 0 0 -27 49 56 10 20 32.5 34 36 -24 -27 40 9 -27 59 45 -27 28 58 -28 11 4 1.27 156 0 0 -27 47 42 10 20 43.0 33 37 -23 -27 37 55 -27 57 31 -27 26 44 -28 8 49 1.27 155 0 0 -27 46 2 10 20 53.3 33 37 -22 -27 36 15 -27 55 50 -27 25 4 -28 7 9 1.27 154 0 0 -27 44 55 10 21 3.5 32 38 -22 -27 35 8 -27 54 43 -27 23 57 -28 6 2 1.27 153 0 0 -27 44 22 10 21 13.5 32 39 -21 -27 34 35 -27 54 10 -27 23 24 -28 5 29 1.27 152 0 0 -27 44 22 10 21 23.4 31 40 -20 -27 34 36 -27 54 11 -27 23 24 -28 5 30 1.27 151 0 0 -27 44 57 10 21 33.2 31 41 -20 -27 35 10 -27 54 46 -27 23 58 -28 6 5 1.27 150 0 0 -27 46 5 10 21 42.8 30 42 -19 -27 36 18 -27 55 54 -27 25 6 -28 7 14 1.27 149 0 0 -27 47 47 10 21 52.3 29 42 -18 -27 38 0 -27 57 37 -27 26 47 -28 8 57 1.27 148 0 0 -27 50 3 10 22 1.5 29 43 -17 -27 40 15 -27 59 53 -27 29 2 -28 11 14 1.28 147 0 0 -27 52 53 10 22 10.6 28 44 -17 -27 43 5 -28 2 44 -27 31 51 -28 14 5 1.28 146 0 0 -27 56 17 10 22 19.6 28 45 -16 -27 46 28 -28 6 9 -27 35 14 -28 17 30 1.28 145 0 0 -28 0 16 10 22 28.3 27 45 -15 -27 50 26 -28 10 8 -27 39 11 -28 21 30 1.28 144 0 0 -28 4 48 10 22 36.9 26 46 -14 -27 54 58 -28 14 41 -27 43 42 -28 26 4 1.28 143 0 0 -28 9 55 10 22 45.3 26 47 -13 -28 0 3 -28 19 48 -27 48 47 -28 31 13 1.28 142 0 0 -28 15 36 10 22 53.4 25 48 -13 -28 5 43 -28 25 30 -27 54 26 -28 36 55 1.28 141 0 0 -28 21 51 10 23 1.4 24 48 -12 -28 11 57 -28 31 46 -28 0 39 -28 43 13 1.28 140 0 0 -28 28 40 10 23 9.2 23 49 -11 -28 18 46 -28 38 36 -28 7 26 -28 50 4 1.29 139 0 0 -28 36 4 10 23 16.7 23 50 -10 -28 26 8 -28 46 1 -28 14 47 -28 57 30 1.29 138 0 0 -28 44 2 10 23 24.1 22 50 -9 -28 34 5 -28 54 0 -28 22 43 -29 5 31 1.29 137 0 0 -28 52 34 10 23 31.2 21 51 -8 -28 42 36 -29 2 34 -28 31 12 -29 14 6 1.29 136 0 0 -29 1 41 10 23 38.0 20 52 -8 -28 51 42 -29 11 42 -28 40 16 -29 23 16 1.29 135 0 0 -29 11 22 10 23 44.7 20 52 -7 -29 1 21 -29 21 25 -28 49 54 -29 33 0 1.29 134 0 0 -29 21 37 10 23 51.1 19 53 -6 -29 11 35 -29 31 41 -29 0 6 -29 43 19 1.30 133 0 0 -29 32 27 10 23 57.3 18 53 -5 -29 22 23 -29 42 33 -29 10 52 -29 54 12 1.30 132 0 0 -29 43 51 10 24 3.2 17 54 -4 -29 33 45 -29 53 58 -29 22 12 -30 5 39 1.30 131 0 0 -29 55 49 10 24 8.9 17 55 -3 -29 45 41 -30 5 58 -29 34 7 -30 17 41 1.30 130 0 0 -30 8 21 10 24 14.3 16 55 -2 -29 58 12 -30 18 32 -29 46 35 -30 30 18 1.30 129 0 0 -30 21 27 10 24 19.5 15 56 -2 -30 11 16 -30 31 41 -29 59 38 -30 43 28 1.31 128 0 0 -30 35 8 10 24 24.4 14 56 -1 -30 24 55 -30 45 23 -30 13 14 -30 57 13 1.31 127 0 0 -30 49 22 10 24 29.0 13 57 0 -30 39 7 -30 59 40 -30 27 24 -31 11 32 1.31 126 0 0 -31 4 11 10 24 33.4 12 57 1 -30 53 54 -31 14 30 -30 42 8 -31 26 25 1.31 125 0 0 -31 19 33 10 24 37.5 12 58 2 -31 9 13 -31 29 55 -30 57 25 -31 41 52 1.32 124 0 0 -31 35 29 10 24 41.3 11 58 3 -31 25 7 -31 45 53 -31 13 16 -31 57 53 1.32 123 0 0 -31 51 58 10 24 44.8 10 59 4 -31 41 34 -32 2 25 -31 29 40 -32 14 28 1.33 122 0 0 -32 9 1 10 24 48.0 9 60 5 -31 58 34 -32 19 30 -31 46 37 -32 31 36 1.33 121 0 0 -32 26 36 10 24 50.9 8 60 5 -32 16 7 -32 37 8 -32 4 8 -32 49 17 1.34 120 0 0 -32 44 45 10 24 53.6 7 61 6 -32 34 13 -32 55 20 -32 22 11 -33 7 32 1.34 119 0 0 -33 3 27 10 24 55.9 6 61 7 -32 52 52 -33 14 4 -32 40 47 -33 26 19 1.35 118 0 0 -33 22 41 10 24 57.9 5 62 8 -33 12 4 -33 33 21 -32 59 55 -33 45 39 1.36 117 0 0 -33 42 27 10 24 59.7 5 62 9 -33 31 47 -33 53 10 -33 19 35 -34 5 32 1.37 116 0 0 -34 2 46 10 25 1.1 4 63 10 -33 52 2 -34 13 31 -33 39 47 -34 25 57 1.39 115 0 0 -34 23 36 10 25 2.2 3 63 11 -34 12 50 -34 34 25 -34 0 31 -34 46 53 1.42 114 0 0 -34 44 57 10 25 3.0 2 64 12 -34 34 8 -34 55 49 -34 21 46 -35 8 22 1.49 113 0 0 -35 6 49 10 25 3.5 1 65 12 -34 55 57 -35 17 45 -34 43 31 -35 30 21 1.65 112 0 0 -35 29 12 10 25 3.7 0 65 13 -35 18 17 -35 40 11 .. .. .. .. .. .. 3.96 Uncertainty in time = +/- 4 secs Prediction of 2020 Dec 31.0 Data for the target star ------------------------ * name: UCAC4 551-042106 * constellation : Gemini * BCRS position with proper motion to date of event [h,m,s ; °,',"] RA: 07 50 40.2667 DE: +20 01 14.055 * GCRS Astrometric position with proper motion and parallax to date of event [h,m,s ; °,',"] RA: 07 50 40.2666 DE: +20 01 14.055 * position source: Gaia EDR3 * standard error: RA,DE [mas]: (0.100,0.100) * V mag [mag]: 10.9 * B mag [mag]: 11.9 * Diameter [mas]: 0.00 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (149) Medusa asteroid class: approx. diameter [km]: 22 approx. diameter ["]: 0.026 distance from Earth [AU]: 1.17300 asteroid position offset in RA [mas]: 0 asteroid position offset in DE [mas]: 0 * orbital information: orbit source: Preston date of fit: 2020 Dec 12 source of used astrometry: MPC, FASTT number of used observations: 3004 number of rejected observations: 14 time covered by the observations: 1960 Jan 28 - 2020 Oct 21 1 sigma uncertainty ellipse (major, minor, PA): 0.034", 0.015", 100° remarks: * orbital elements for (149)Medusa : Mean anomaly = 66.85289187 deg Arg. of pericenter = 251.32248791 deg Long. of node = 159.59512958 deg Inclination = 0.93951261 deg Eccentricity = 0.06510765 Semimajor axis = 2.17488343 AU Perihelion dist = 2.03328187 AU Mag: H = 10.50, G = 0.15 Epoch of elements : MJD 59249.42800000 TDT (2021 Feb 04.4280) ------ occelmnt file for Occult BEGIN ----------------------------------- Preston2020Dec12,2.8,2021,2,4,10.2803,-0.18405,-0.76101,-4.39047,1.06267,0.00183,-0.00026,0.00000,0.00000 -171.0271,19.9661,29.28,-16.09,False UCAC4 551-042106,7.84451851,20.0205708,11.90,10.90,10.36,0.0,0,,7.86514288,19.9660536 149,Medusa,13.09,22.4,1.1730,0,0,-2.333,7.96,,1.4 0,66.7214,2021,2,4,251.3225,159.5951,0.9395,0.06511,2.17488,2.03328,10.50,5.0,0.15 1.574,0.0340,0.0150,100,0.0151,Known errors 20210204_042106,59214.00 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2020 Dec 31, 01:02 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 stevepr@acm.org