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Updated: 2021 MAY 17, 22:53 UT
Event Rank : 99
(The event Rank is a measure of the likelihood of observing an event, and is equal to the probability of at least one successful observation by a team of two observers spaced 1/8 path width just inside opposite sides of the predicted path. An event rank of 100 indicates that the prediction is expected to be very accurate).
THE UPDATED PATH
Note: The duration given in the line below is the interval during which the occultation shadow sweeps across the Earth - please see the minute markers on the map to determine the approximate time for your location.
On 2021 Jul 13 UT, the 77.7 km diameter asteroid (1031) Arctica will occult a 12.5 mag star in the constellation Pegasus for observers along a path across south-eastern Australia from Portland across western Victoria and New South Wales and across south-eastern Queensland in morning twilight to Rockhampton.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.87 mag to 15.29 mag (the magnitude of the asteroid) for at most 10.0 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, inparticular the institutions participating in the Gaia Multilateral Agreement.
Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/
EVENT DETAILS SUMMARY :Important Note regarding Accuracy:
The uncertainty interval in path widths given above (and shown as a 1-sigma uncertainty ellipse on the plot) refers to RMS deviation and is applied as a +/- range. In other words, a path uncertainty of 1.0 path widths means that the actual center of the asteroid's shadow path should fall within plus or minus 1 path width of the plotted path center. However path errors larger than 1 sigma have been observed so observers should be alert for primary occultations within plus or minus 3 sigma of the updated path.
Further, almost all asteroidal satellites discovered so far have been found within 10 diameters of the asteroid (since this distance is deep enough within the gravitational well to be stable over long timescales). Therefore, if monitoring for secondary events, observing out to about 10 path-widths either side of the predicted track remains worthwhile.
We therefore recommend that you monitor for events if your observing location is up to +/- 10 path-widths from the predicted track. If not monitoring for occultations by secondary bodies you should observe from locations within 3 sigma of the nominal path.
In terms of time, the predictions are now usually accurate to about +/- 0.3 minute so you should be most attentive during the predicted minute of the event. However if intending to catch a potential satellite occultation you should start observing at least 10 times the predicted central duration before the predicted closest approach time for your location, and continue for a similar period afterwards.
Occultation of UCAC4-535-147948 by 1031 Arctica on 2021 Jul 13
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
140 3 5 -44 0 0 19 57 1.4 28 347 -23 140 43 16 139 23 9 140 59 37 139 7 1 0.86
140 25 51 -43 0 0 19 57 11.0 29 347 -23 141 5 29 139 46 26 141 21 37 139 30 32 0.86
140 49 10 -42 0 0 19 57 21.0 30 346 -22 141 28 18 140 10 16 141 44 14 139 54 33 0.86
141 13 3 -41 0 0 19 57 31.3 31 346 -22 141 51 43 140 34 36 142 7 28 140 19 5 0.86
141 37 29 -40 0 0 19 57 41.8 32 345 -21 142 15 44 140 59 28 142 31 17 140 44 8 0.86
142 2 29 -39 0 0 19 57 52.7 33 344 -21 142 40 20 141 24 52 142 55 44 141 9 41 0.86
142 28 3 -38 0 0 19 58 3.9 33 344 -20 143 5 31 141 50 48 143 20 46 141 35 47 0.87
142 54 11 -37 0 0 19 58 15.4 34 343 -20 143 31 19 142 17 17 143 46 26 142 2 24 0.87
143 20 54 -36 0 0 19 58 27.2 35 342 -19 143 57 43 142 44 19 144 12 43 142 29 33 0.87
143 48 13 -35 0 0 19 58 39.4 36 341 -18 144 24 45 143 11 55 144 39 37 142 57 16 0.87
144 16 7 -34 0 0 19 58 51.8 37 340 -18 144 52 24 143 40 5 145 7 10 143 25 32 0.87
144 44 39 -33 0 0 19 59 4.5 37 340 -17 145 20 42 144 8 50 145 35 22 143 54 23 0.87
145 13 48 -32 0 0 19 59 17.5 38 339 -16 145 49 39 144 38 12 146 4 14 144 23 50 0.87
145 43 37 -31 0 0 19 59 30.8 39 338 -16 146 19 16 145 8 11 146 33 48 144 53 54 0.88
146 14 5 -30 0 0 19 59 44.5 40 337 -15 146 49 36 145 38 49 147 4 3 145 24 35 0.88
146 45 15 -29 0 0 19 59 58.4 40 336 -14 147 20 38 146 10 6 147 35 2 145 55 56 0.88
147 17 7 -28 0 0 20 0 12.6 41 335 -13 147 52 24 146 42 5 148 6 47 146 27 58 0.88
147 49 44 -27 0 0 20 0 27.1 42 334 -13 148 24 57 147 14 47 148 39 17 147 0 41 0.88
148 23 7 -26 0 0 20 0 41.9 42 332 -12 148 58 17 147 48 13 149 12 36 147 34 9 0.88
148 57 18 -25 0 0 20 0 57.0 43 331 -11 149 32 26 148 22 26 149 46 45 148 8 22 0.89
149 32 19 -24 0 0 20 1 12.3 44 330 -10 150 7 27 148 57 27 150 21 46 148 43 23 0.89
150 8 12 -23 0 0 20 1 28.0 44 329 -9 150 43 22 149 33 18 150 57 42 149 19 14 0.89
150 44 59 -22 0 0 20 1 44.0 45 327 -8 151 20 13 150 10 3 151 34 35 149 55 58 0.89
151 22 44 -21 0 0 20 2 0.2 45 326 -7 151 58 3 150 47 43 152 12 28 150 33 36 0.89
152 1 29 -20 0 0 20 2 16.8 46 325 -6 152 36 56 151 26 21 152 51 23 151 12 11 0.90
152 41 17 -19 0 0 20 2 33.6 46 323 -5 153 16 53 152 6 0 153 31 24 151 51 48 0.90
153 22 12 -18 0 0 20 2 50.7 46 322 -4 153 57 59 152 46 45 154 12 36 152 32 28 0.90
154 4 18 -17 0 0 20 3 8.1 47 320 -3 154 40 18 153 28 37 154 55 0 153 14 16 0.90
154 47 38 -16 0 0 20 3 25.9 47 319 -2 155 23 54 154 11 43 155 38 43 153 57 15 0.91
155 32 17 -15 0 0 20 3 43.9 47 317 -1 156 8 52 154 56 5 156 23 48 154 41 30 0.91
156 18 21 -14 0 0 20 4 2.2 47 316 0 156 55 17 155 41 48 157 10 22 155 27 6 0.91
157 5 54 -13 0 0 20 4 20.8 47 314 1 157 43 15 156 28 59 157 58 30 156 14 8 0.91
157 55 4 -12 0 0 20 4 39.7 47 312 3 158 32 52 157 17 43 158 48 18 157 2 42 0.92
158 45 57 -11 0 0 20 4 59.0 47 311 4 159 24 15 158 8 6 159 39 55 157 52 54 0.92
159 38 41 -10 0 0 20 5 18.5 47 309 5 160 17 34 159 0 17 160 33 29 158 44 52 0.92
160 33 25 - 9 0 0 20 5 38.4 47 307 6 161 12 58 159 54 24 161 29 9 159 38 43 0.92
161 30 19 - 8 0 0 20 5 58.7 47 306 8 162 10 36 160 50 35 162 27 6 160 34 39 0.93
Uncertainty in time = +/- 3 secs
Prediction of 2021 May 17.0
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