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Updated: 2020 Mar 14, 22:58 UT
Event Rank : 82
(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 2020 Apr 25 UT, the 64 km diameter asteroid (546) Herodias will occult a 11.6 mag star in the constellation Scorpius for observers along a slightly uncertain path across eastern Northern Territory and western South Australia, passing over Tennant Creek and Alice Springs.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.81 mag to 14.34 mag (the magnitude of the asteroid) for at most 8.1 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, astrometry for the asteroid kindly provided by Bill Owen, 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.
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 TYC 7886-01425-1 by 546 Herodias on 2020 Apr 25
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
135 55 34 -10 0 0 19 3 0.7 60 190 -29 135 37 49 136 13 18 135 19 54 136 31 13 0.01
135 46 27 -11 0 0 19 3 13.0 61 190 -29 135 28 39 136 4 14 135 10 40 136 22 13 0.01
135 37 18 -12 0 0 19 3 25.4 62 190 -30 135 19 26 135 55 9 135 1 23 136 13 12 0.01
135 28 7 -13 0 0 19 3 37.9 63 190 -30 135 10 11 135 46 2 134 52 4 136 4 9 0.01
135 18 54 -14 0 0 19 3 50.6 64 190 -30 135 0 54 135 36 54 134 42 42 135 55 5 0.01
135 9 39 -15 0 0 19 4 3.4 65 190 -30 134 51 33 135 27 43 134 33 17 135 46 0 0.02
135 0 21 -16 0 0 19 4 16.2 66 191 -31 134 42 11 135 18 31 134 23 48 135 36 53 0.02
134 51 0 -17 0 0 19 4 29.2 67 191 -31 134 32 45 135 9 16 134 14 17 135 27 43 0.02
134 41 37 -18 0 0 19 4 42.3 68 191 -31 134 23 15 134 59 59 134 4 41 135 18 32 0.02
134 32 11 -19 0 0 19 4 55.4 69 191 -31 134 13 43 134 50 39 133 55 2 135 9 19 0.02
134 22 41 -20 0 0 19 5 8.6 70 192 -31 134 4 6 134 41 17 133 45 19 135 0 3 0.02
134 13 9 -21 0 0 19 5 22.0 71 192 -31 133 54 26 134 31 51 133 35 31 134 50 45 0.02
134 3 32 -22 0 0 19 5 35.4 72 193 -32 133 44 42 134 22 22 133 25 39 134 41 24 0.02
133 53 52 -23 0 0 19 5 48.8 73 193 -32 133 34 53 134 12 50 133 15 42 134 32 0 0.02
133 44 7 -24 0 0 19 6 2.4 74 193 -32 133 25 0 134 3 14 133 5 41 134 22 33 0.02
133 34 18 -25 0 0 19 6 16.0 75 194 -32 133 15 2 133 53 34 132 55 33 134 13 2 0.03
133 24 25 -26 0 0 19 6 29.7 76 195 -32 133 4 59 133 43 50 132 45 20 134 3 28 0.03
133 14 26 -27 0 0 19 6 43.4 77 195 -32 132 54 50 133 34 2 132 35 2 133 53 50 0.03
133 4 23 -28 0 0 19 6 57.2 78 196 -32 132 44 36 133 24 9 132 24 37 133 44 8 0.03
132 54 14 -29 0 0 19 7 11.1 79 197 -32 132 34 16 133 14 11 132 14 5 133 34 22 0.03
132 43 59 -30 0 0 19 7 25.0 80 199 -32 132 23 49 133 4 9 132 3 26 133 24 31 0.03
132 33 38 -31 0 0 19 7 38.9 81 200 -32 132 13 16 132 54 0 131 52 40 133 14 35 0.03
132 23 11 -32 0 0 19 7 52.9 82 202 -33 132 2 35 132 43 46 131 41 46 133 4 34 0.03
132 12 36 -33 0 0 19 8 6.9 83 204 -33 131 51 47 132 33 25 131 30 44 132 54 27 0.04
132 1 55 -34 0 0 19 8 20.9 84 208 -33 131 40 51 132 22 58 131 19 33 132 44 14 0.04
131 51 5 -35 0 0 19 8 35.0 84 212 -33 131 29 46 132 12 24 131 8 13 132 33 56 0.04
131 40 8 -36 0 0 19 8 49.1 85 218 -33 131 18 33 132 1 42 130 56 44 132 23 30 0.04
131 29 1 -37 0 0 19 9 3.2 86 228 -32 131 7 10 131 50 53 130 45 3 132 12 57 0.05
Uncertainty in time = +/- 4 secs
Prediction of 2020 Mar 14.0
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