IOTA/IOTA-ES occultation update for (3652) Soros / HIP 71234 event on 2024 Jan 18, 01:29 UT Visible from Summary ------- On 2024 Jan 18 UT, the 13.24196599362 km diameter asteroid (3652) Soros will occult a 7.2 mag star in the constellation Libra for observers along a path across . In the case of an occultation, the combined light of the asteroid and the star will drop by 11.28 mag to 18.45 mag (the magnitude of the asteroid) for at most 0.520 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: 99 * date and approx. time of event: 2024 Jan 18, 01:26 - 2024 Jan 18, 01:32 * geocentric midpoint of event [JD]: 2460327.56201292 * magnitude of target star: 7.17 * magnitude drop [mag]: 11.28 * estimated maximum duration [s]: 0.520 * Moon: 48 % sunlit, 163° distance * Sun: 76° distance * rough path description: The occultation path -------------------- * approximate projected width [km]: 17 * 1 sigma uncertainty interval [path widths]: +/- 0.27 * 1 sigma uncertainty interval [seconds]: +/- 0.9 * 1 sigma uncertainty interval approx RA,DE ["]: (+/- 0.012, +/- 0.004) * 1 sigma uncertainty ellipse (major, minor, PA): (0.013", 0.002", 107°) * approx speed of asteroid's shadow [km/s]: 26.0212 * website for maps: http://www.asteroidoccultation.com Path Coordinates: Occultation of HIP 71234 by 3652 Soros on 2024 Jan 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 15 0 0 52 54 53 1 26 6.2 1 120 -49 52 49 36 53 0 10 52 46 47 53 2 59 .... 16 0 0 52 34 25 1 26 6.3 1 120 -48 52 29 8 52 39 42 52 26 18 52 42 32 -0.42 17 0 0 52 13 34 1 26 6.4 2 121 -48 52 8 17 52 18 53 52 5 27 52 21 43 -0.55 18 0 0 51 52 22 1 26 6.5 3 122 -48 51 47 4 51 57 41 51 44 13 52 0 32 -0.61 19 0 0 51 30 48 1 26 6.7 3 123 -47 51 25 29 51 36 8 51 22 38 51 38 59 -0.64 20 0 0 51 8 52 1 26 7.0 4 123 -47 51 3 32 51 14 13 51 0 41 51 17 4 -0.67 21 0 0 50 46 34 1 26 7.3 5 124 -47 50 41 14 50 51 56 50 38 23 50 54 47 -0.68 22 0 0 50 23 55 1 26 7.7 6 125 -46 50 18 34 50 29 17 50 15 42 50 32 9 -0.70 23 0 0 50 0 55 1 26 8.1 6 126 -46 49 55 33 50 6 18 49 52 41 50 9 10 -0.71 24 0 0 49 37 34 1 26 8.6 7 127 -45 49 32 11 49 42 57 49 29 19 49 45 50 -0.71 25 0 0 49 13 52 1 26 9.1 8 127 -45 49 8 28 49 19 15 49 5 36 49 22 8 -0.72 26 0 0 48 49 49 1 26 9.7 9 128 -44 48 44 25 48 55 13 48 41 32 48 58 6 -0.73 27 0 0 48 25 26 1 26 10.3 9 129 -44 48 20 2 48 30 51 48 17 9 48 33 44 -0.73 28 0 0 48 0 44 1 26 11.1 10 130 -44 47 55 19 48 6 9 47 52 26 48 9 3 -0.73 29 0 0 47 35 42 1 26 11.8 11 130 -43 47 30 16 47 41 7 47 27 23 47 44 1 -0.74 30 0 0 47 10 20 1 26 12.7 12 131 -42 47 4 55 47 15 46 47 2 1 47 18 41 -0.74 31 0 0 46 44 41 1 26 13.6 13 132 -42 46 39 15 46 50 7 46 36 21 46 53 2 -0.74 32 0 0 46 18 43 1 26 14.6 13 133 -41 46 13 17 46 24 10 46 10 23 46 27 4 -0.74 33 0 0 45 52 28 1 26 15.7 14 133 -41 45 47 1 45 57 55 45 44 7 46 0 50 -0.75 34 0 0 45 25 55 1 26 16.8 15 134 -40 45 20 28 45 31 22 45 17 34 45 34 17 -0.75 35 0 0 44 59 6 1 26 18.0 16 135 -40 44 53 39 45 4 33 44 50 45 45 7 29 -0.75 36 0 0 44 32 1 1 26 19.3 17 136 -39 44 26 34 44 37 29 44 23 39 44 40 24 -0.75 37 0 0 44 4 41 1 26 20.6 17 137 -38 43 59 13 44 10 8 43 56 19 44 13 4 -0.75 38 0 0 43 37 6 1 26 22.1 18 137 -38 43 31 38 43 42 33 43 28 43 43 45 29 -0.75 39 0 0 43 9 17 1 26 23.6 19 138 -37 43 3 49 43 14 44 43 0 54 43 17 40 -0.76 40 0 0 42 41 14 1 26 25.2 20 139 -36 42 35 47 42 46 42 42 32 52 42 49 37 -0.76 41 0 0 42 12 59 1 26 26.8 21 140 -36 42 7 32 42 18 27 42 4 37 42 21 22 -0.76 42 0 0 41 44 32 1 26 28.6 22 140 -35 41 39 5 41 50 0 41 36 10 41 52 55 -0.76 43 0 0 41 15 54 1 26 30.4 22 141 -34 41 10 27 41 21 22 41 7 32 41 24 17 -0.76 44 0 0 40 47 6 1 26 32.3 23 142 -33 40 41 39 40 52 34 40 38 44 40 55 29 -0.76 45 0 0 40 18 9 1 26 34.3 24 143 -33 40 12 42 40 23 36 40 9 47 40 26 31 -0.76 46 0 0 39 49 3 1 26 36.3 25 144 -32 39 43 36 39 54 30 39 40 41 39 57 25 -0.76 47 0 0 39 19 49 1 26 38.5 26 144 -31 39 14 23 39 25 16 39 11 28 39 28 11 -0.76 48 0 0 38 50 29 1 26 40.7 27 145 -30 38 45 2 38 55 56 38 42 8 38 58 50 -0.76 49 0 0 38 21 3 1 26 43.0 28 146 -29 38 15 37 38 26 29 38 12 43 38 29 24 -0.76 50 0 0 37 51 32 1 26 45.4 28 147 -29 37 46 6 37 56 58 37 43 12 37 59 52 -0.77 51 0 0 37 21 57 1 26 47.9 29 148 -28 37 16 31 37 27 22 37 13 38 37 30 17 -0.77 52 0 0 36 52 18 1 26 50.4 30 148 -27 36 46 54 36 57 44 36 44 0 37 0 38 -0.77 53 0 0 36 22 38 1 26 53.0 31 149 -26 36 17 14 36 28 3 36 14 20 36 30 57 -0.77 54 0 0 35 52 56 1 26 55.7 32 150 -25 35 47 33 35 58 21 35 44 40 36 1 14 -0.77 55 0 0 35 23 15 1 26 58.5 33 151 -24 35 17 52 35 28 39 35 14 59 35 31 32 -0.77 56 0 0 34 53 35 1 27 1.4 33 152 -23 34 48 12 34 58 58 34 45 19 35 1 51 -0.77 57 0 0 34 23 56 1 27 4.3 34 153 -22 34 18 34 34 29 18 34 15 42 34 32 11 -0.77 58 0 0 33 54 20 1 27 7.3 35 154 -22 33 48 58 33 59 42 33 46 7 34 2 34 -0.77 59 0 0 33 24 48 1 27 10.4 36 155 -21 33 19 27 33 30 9 33 16 36 33 33 1 -0.77 60 0 0 32 55 21 1 27 13.6 37 156 -20 32 50 0 33 0 41 32 47 9 33 3 33 -0.77 61 0 0 32 25 59 1 27 16.8 37 157 -19 32 20 40 32 31 19 32 17 49 32 34 11 -0.77 62 0 0 31 56 45 1 27 20.1 38 158 -18 31 51 26 32 2 4 31 48 36 32 4 55 -0.77 63 0 0 31 27 38 1 27 23.5 39 159 -17 31 22 20 31 32 57 31 19 30 31 35 47 -0.77 64 0 0 30 58 40 1 27 26.9 40 160 -16 30 53 23 31 3 58 30 50 33 31 6 48 -0.77 65 0 0 30 29 52 1 27 30.4 41 161 -15 30 24 35 30 35 9 30 21 46 30 37 58 -0.77 66 0 0 30 1 14 1 27 34.0 41 162 -14 29 55 58 30 6 30 29 53 10 30 9 20 -0.78 67 0 0 29 32 48 1 27 37.6 42 163 -13 29 27 33 29 38 3 29 24 45 29 40 52 -0.78 68 0 0 29 4 35 1 27 41.2 43 164 -12 28 59 20 29 9 49 28 56 33 29 12 38 -0.78 69 0 0 28 36 34 1 27 45.0 43 166 -11 28 31 21 28 41 48 28 28 34 28 44 36 -0.78 70 0 0 28 8 49 1 27 48.8 44 167 -10 28 3 36 28 14 2 28 0 49 28 16 49 -0.78 71 0 0 27 41 18 1 27 52.6 45 168 -9 27 36 6 27 46 30 27 33 20 27 49 17 -0.78 72 0 0 27 14 3 1 27 56.5 45 169 -8 27 8 52 27 19 14 27 6 6 27 22 1 -0.78 73 0 0 26 47 5 1 28 0.4 46 171 -7 26 41 55 26 52 16 26 39 10 26 55 2 -0.78 74 0 0 26 20 25 1 28 4.4 46 172 -6 26 15 16 26 25 34 26 12 31 26 28 20 -0.78 75 0 0 25 54 3 1 28 8.4 47 173 -5 25 48 55 25 59 12 25 46 11 26 1 57 -0.78 76 0 0 25 28 1 1 28 12.5 48 175 -4 25 22 54 25 33 8 25 20 9 25 35 53 -0.78 77 0 0 25 2 18 1 28 16.6 48 176 -3 24 57 12 25 7 25 24 54 28 25 10 9 -0.78 78 0 0 24 36 56 1 28 20.7 49 177 -2 24 31 51 24 42 2 24 29 8 24 44 46 -0.78 79 0 0 24 11 56 1 28 24.8 49 179 -1 24 6 51 24 17 1 24 4 9 24 19 44 -0.78 80 0 0 23 47 17 1 28 29.0 49 180 0 23 42 14 23 52 22 23 39 32 23 55 4 -0.78 81 0 0 23 23 2 1 28 33.2 50 182 1 23 17 59 23 28 5 23 15 17 23 30 47 -0.78 82 0 0 22 59 9 1 28 37.5 50 183 2 22 54 8 23 4 12 22 51 26 23 6 53 -0.78 83 0 0 22 35 41 1 28 41.7 50 185 3 22 30 40 22 40 43 22 27 59 22 43 24 -0.78 84 0 0 22 12 37 1 28 46.0 51 187 4 22 7 37 22 17 38 22 4 57 22 20 19 -0.78 85 0 0 21 49 59 1 28 50.3 51 188 5 21 44 59 21 54 58 21 42 20 21 57 39 -0.79 86 0 0 21 27 46 1 28 54.6 51 190 6 21 22 47 21 32 45 21 20 8 21 35 24 -0.79 87 0 0 21 5 59 1 28 58.9 51 191 7 21 1 1 21 10 57 20 58 23 21 13 36 -0.79 88 0 0 20 44 39 1 29 3.3 52 193 8 20 39 42 20 49 36 20 37 4 20 52 15 -0.79 89 0 0 20 23 46 1 29 7.6 52 195 9 20 18 50 20 28 42 20 16 12 20 31 21 -0.79 90 0 0 20 3 21 1 29 11.9 52 196 10 19 58 26 20 8 16 19 55 48 20 10 54 -0.79 91 0 0 19 43 24 1 29 16.3 52 198 11 19 38 29 19 48 18 19 35 52 19 50 56 -0.79 92 0 0 19 23 55 1 29 20.6 52 199 12 19 19 1 19 28 49 19 16 25 19 31 26 -0.79 93 0 0 19 4 55 1 29 24.9 52 201 13 19 0 2 19 9 48 18 57 26 19 12 25 -0.79 94 0 0 18 46 24 1 29 29.2 52 203 14 18 41 32 18 51 17 18 38 56 18 53 53 -0.79 95 0 0 18 28 23 1 29 33.5 52 204 15 18 23 32 18 33 15 18 20 56 18 35 51 -0.79 96 0 0 18 10 52 1 29 37.8 51 206 16 18 6 1 18 15 43 18 3 26 18 18 18 -0.79 97 0 0 17 53 51 1 29 42.1 51 207 17 17 49 1 17 58 41 17 46 26 18 1 16 -0.79 98 0 0 17 37 20 1 29 46.4 51 209 18 17 32 31 17 42 10 17 29 57 17 44 45 -0.79 99 0 0 17 21 21 1 29 50.7 51 210 19 17 16 32 17 26 10 17 13 58 17 28 44 -0.79 100 0 0 17 5 52 1 29 54.9 50 212 20 17 1 5 17 10 40 16 58 31 17 13 14 -0.79 101 0 0 16 50 55 1 29 59.1 50 213 21 16 46 8 16 55 42 16 43 35 16 58 16 -0.79 102 0 0 16 36 29 1 30 3.3 50 215 22 16 31 43 16 41 16 16 29 10 16 43 49 -0.79 103 0 0 16 22 35 1 30 7.4 49 216 23 16 17 49 16 27 21 16 15 17 16 29 54 -0.79 104 0 0 16 9 13 1 30 11.6 49 218 24 16 4 28 16 13 59 16 1 56 16 16 32 -0.79 105 0 0 15 56 23 1 30 15.7 49 219 25 15 51 39 16 1 8 15 49 6 16 3 41 -0.79 106 0 0 15 44 6 1 30 19.7 48 220 26 15 39 21 15 48 50 15 36 50 15 51 22 -0.79 107 0 0 15 32 20 1 30 23.8 48 221 27 15 27 37 15 37 4 15 25 5 15 39 36 -0.79 108 0 0 15 21 8 1 30 27.8 47 223 28 15 16 25 15 25 51 15 13 53 15 28 23 -0.79 109 0 0 15 10 28 1 30 31.7 47 224 29 15 5 45 15 15 11 15 3 14 15 17 42 -0.79 110 0 0 15 0 21 1 30 35.6 46 225 29 14 55 39 15 5 4 14 53 8 15 7 35 -0.79 111 0 0 14 50 47 1 30 39.5 45 226 30 14 46 5 14 55 29 14 43 35 14 58 0 -0.79 112 0 0 14 41 46 1 30 43.4 45 227 31 14 37 5 14 46 28 14 34 35 14 48 59 -0.79 113 0 0 14 33 19 1 30 47.2 44 228 32 14 28 38 14 38 0 14 26 8 14 40 30 -0.79 114 0 0 14 25 24 1 30 50.9 44 229 33 14 20 44 14 30 5 14 18 14 14 32 35 -0.79 115 0 0 14 18 3 1 30 54.6 43 230 34 14 13 23 14 22 44 14 10 53 14 25 14 -0.79 116 0 0 14 11 15 1 30 58.2 42 231 35 14 6 35 14 15 56 14 4 6 14 18 26 -0.79 117 0 0 14 5 1 1 31 1.8 41 232 36 14 0 21 14 9 41 13 57 52 14 12 11 -0.79 118 0 0 13 59 20 1 31 5.4 41 232 36 13 54 41 14 4 0 13 52 12 14 6 30 -0.79 119 0 0 13 54 13 1 31 8.9 40 233 37 13 49 34 13 58 53 13 47 5 14 1 22 -0.79 120 0 0 13 49 40 1 31 12.3 39 234 38 13 45 1 13 54 19 13 42 32 13 56 48 -0.80 121 0 0 13 45 40 1 31 15.7 39 235 39 13 41 1 13 50 19 13 38 32 13 52 48 -0.80 122 0 0 13 42 13 1 31 19.0 38 236 40 13 37 35 13 46 52 13 35 6 13 49 21 -0.80 123 0 0 13 39 21 1 31 22.2 37 236 40 13 34 42 13 43 59 13 32 14 13 46 29 -0.80 124 0 0 13 37 2 1 31 25.4 36 237 41 13 32 23 13 41 40 13 29 55 13 44 9 -0.80 125 0 0 13 35 17 1 31 28.6 35 238 42 13 30 38 13 39 55 13 28 10 13 42 24 -0.80 126 0 0 13 34 5 1 31 31.6 35 238 42 13 29 27 13 38 43 13 26 58 13 41 12 -0.80 127 0 0 13 33 27 1 31 34.6 34 239 43 13 28 49 13 38 5 13 26 20 13 40 34 -0.80 128 0 0 13 33 22 1 31 37.6 33 239 44 13 28 44 13 38 0 13 26 16 13 40 29 -0.80 129 0 0 13 33 51 1 31 40.5 32 240 44 13 29 13 13 38 30 13 26 45 13 40 58 -0.80 130 0 0 13 34 54 1 31 43.3 31 240 45 13 30 16 13 39 32 13 27 47 13 42 1 -0.80 131 0 0 13 36 30 1 31 46.0 30 241 46 13 31 52 13 41 8 13 29 23 13 43 37 -0.80 132 0 0 13 38 39 1 31 48.7 29 241 46 13 34 1 13 43 18 13 31 33 13 45 47 -0.80 133 0 0 13 41 22 1 31 51.2 28 242 47 13 36 44 13 46 1 13 34 15 13 48 30 -0.80 134 0 0 13 44 39 1 31 53.8 28 242 47 13 40 0 13 49 17 13 37 31 13 51 46 -0.80 135 0 0 13 48 28 1 31 56.2 27 243 48 13 43 50 13 53 7 13 41 21 13 55 36 -0.80 136 0 0 13 52 51 1 31 58.6 26 243 48 13 48 12 13 57 30 13 45 43 13 59 59 -0.80 137 0 0 13 57 47 1 32 0.9 25 244 49 13 53 8 14 2 26 13 50 39 14 4 55 -0.80 138 0 0 14 3 16 1 32 3.1 24 244 49 13 58 37 14 7 55 13 56 7 14 10 25 -0.80 139 0 0 14 9 18 1 32 5.2 23 244 50 14 4 38 14 13 57 14 2 9 14 16 27 -0.80 140 0 0 14 15 52 1 32 7.3 22 245 50 14 11 13 14 20 32 14 8 43 14 23 2 -0.80 141 0 0 14 23 0 1 32 9.2 21 245 51 14 18 20 14 27 40 14 15 50 14 30 10 -0.80 142 0 0 14 30 40 1 32 11.1 20 245 51 14 26 0 14 35 20 14 23 30 14 37 51 -0.80 143 0 0 14 38 52 1 32 12.9 19 246 51 14 34 12 14 43 33 14 31 42 14 46 4 -0.80 144 0 0 14 47 37 1 32 14.7 18 246 51 14 42 57 14 52 19 14 40 26 14 54 49 -0.80 145 0 0 14 56 55 1 32 16.3 17 247 52 14 52 13 15 1 36 14 49 43 15 4 7 -0.80 146 0 0 15 6 44 1 32 17.9 16 247 52 15 2 3 15 11 26 14 59 32 15 13 57 -0.80 147 0 0 15 17 6 1 32 19.3 15 247 52 15 12 24 15 21 48 15 9 53 15 24 19 -0.80 148 0 0 15 27 59 1 32 20.7 14 247 52 15 23 16 15 32 42 15 20 45 15 35 13 -0.80 149 0 0 15 39 24 1 32 22.0 14 248 52 15 34 41 15 44 7 15 32 9 15 46 39 -0.80 150 0 0 15 51 20 1 32 23.2 13 248 52 15 46 36 15 56 4 15 44 5 15 58 35 -0.81 151 0 0 16 3 47 1 32 24.4 12 248 52 15 59 3 16 8 32 15 56 32 16 11 4 -0.81 152 0 0 16 16 46 1 32 25.4 11 249 52 16 12 1 16 21 31 16 9 29 16 24 3 -0.81 153 0 0 16 30 15 1 32 26.3 10 249 52 16 25 30 16 35 0 16 22 58 16 37 33 -0.81 154 0 0 16 44 15 1 32 27.2 9 249 52 16 39 29 16 49 1 16 36 57 16 51 34 -0.81 155 0 0 16 58 45 1 32 27.9 8 250 52 16 53 59 17 3 32 16 51 26 17 6 5 -0.82 156 0 0 17 13 46 1 32 28.6 7 250 52 17 8 59 17 18 33 17 6 26 17 21 6 -0.82 157 0 0 17 29 16 1 32 29.2 6 250 52 17 24 28 17 34 4 17 21 55 17 36 38 -0.83 158 0 0 17 45 15 1 32 29.7 5 251 52 17 40 27 17 50 4 17 37 54 17 52 38 -0.84 159 0 0 18 1 44 1 32 30.1 4 251 51 17 56 56 18 6 34 17 54 22 18 9 8 -0.85 160 0 0 18 18 42 1 32 30.4 3 251 51 18 13 53 18 23 32 18 11 18 18 26 7 -0.88 161 0 0 18 36 9 1 32 30.6 2 252 51 18 31 19 18 41 0 18 28 44 18 43 35 -0.93 162 0 0 18 54 4 1 32 30.7 1 252 50 18 49 13 18 58 55 18 46 38 19 1 31 -1.13 Uncertainty in time = +/- 1 secs Prediction of 2023 Jul 12.0 Data for the target star ------------------------ * name: HIP 71234 * constellation : Libra * BCRS position with proper motion to date of event [h,m,s ; °,',"] RA: 14 34 03.7502 DE: -16 49 10.626 * GCRS Astrometric position with proper motion and parallax to date of event [h,m,s ; °,',"] RA: 14 34 03.7506 DE: -16 49 10.628 * position source: Gaia DR3 * standard error: RA,DE [mas]: (0.300,0.400) * V mag [mag]: 7.2 * B mag [mag]: 7.2 * Diameter [mas]: 0.10 * remarks: Data for the minor planet ------------------------- * general information: (number) name: (3652) Soros asteroid class: approx. diameter [km]: 13 approx. diameter ["]: 0.007 distance from Earth [AU]: 2.48230 asteroid position offset in RA [mas]: 0 asteroid position offset in DE [mas]: 0 * orbital information: orbit source: JPL#46 date of fit: 2023 Apr 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): 0.013", 0.002", 107.158° remarks: * orbital elements for (3652)Soros : Mean anomaly = 272.5915451630 deg Arg. of pericenter = 62.2225605056 deg Long. of node = 245.3208408316 deg Inclination = 2.2713864461 deg Eccentricity = 0.1926000096 Semimajor axis = 2.3665662708 AU Perihelion dist = 1.9107655844 AU Mag: H = 13.45, G = 0.15 Epoch of elements : MJD 60327.06201287 TDT (2024 Jan 18.0620) ------ occelmnt file for Occult BEGIN ----------------------------------- JPL#462023Apr24,0.52,2024,1,18,1.488310,0.193220,0.587378,13.943527,-4.613992,-0.005375,0.001710,0.000000,0.000000 79.5526,-16.9246,160.21,-20.67,False HIP 71234,14.56770835,-16.8196182,7.22,7.17,7.14,0.1,0,,14.58972181,-16.9245520,11.28,10.86,0,0,0 3652,Soros,18.45,13.422,2.4823,0,0,3.443,-16.35,,1.0,0 0,272.3040,2024,1,17,62.2226,245.3208,2.2714,0.19260,2.36657,1.91077,13.45,5.0,0.15 1.267,0.0130,0.0020,107,0.0020,Known errors,0.80,0,-1,-1 20240118__71234,60137.02 ------ occelmnt file for Occult END ----------------------------------- ============================================ Calculator (s): Steve Preston Date of update: 2023 Jul 12, 00:27 UT Steve Preston 7640 NE 32nd St Medina, WA 98039 stevepr@acm.org