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Updated: 2021 Mar 17, 03:42 UT
Event Rank : 51
(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 Apr 12 UT, the 19.2 km diameter asteroid (839) Valborg will occult a 7.9 mag star in the constellation Scorpius for observers along a somewhat uncertain path across New Zealand, passing over Queenstown, Alexandra and Invercargill.
In the case of an occultation, the combined light of the asteroid and the star will drop by 7.14 mag to 15.04 mag (the magnitude of the asteroid) for at most 2.4 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.
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 HIP 86810 by 839 Valborg on 2021 Apr 12
Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 Alt
E. Longitude Latitude U.T. Alt Az Alt Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
166 48 28 -40 59 5 14 6 40.1 55 105 -54 166 57 10 -40 57 56 166 39 44 -41 0 12 167 18 57 -40 55 1 166 17 46 -41 2 59 0.60
166 57 3 -41 19 43 14 6 44.4 55 104 -54 167 5 47 -41 18 34 166 48 17 -41 20 52 167 27 40 -41 15 37 166 26 13 -41 23 40 0.60
167 5 36 -41 40 20 14 6 48.7 55 104 -53 167 14 23 -41 39 10 166 56 48 -41 41 29 167 36 21 -41 36 10 166 34 39 -41 44 20 0.60
167 14 9 -42 0 54 14 6 53.0 55 103 -53 167 22 58 -41 59 43 167 5 18 -42 2 4 167 45 1 -41 56 42 166 43 3 -42 4 57 0.60
167 22 40 -42 21 26 14 6 57.3 55 103 -53 167 31 31 -42 20 15 167 13 47 -42 22 37 167 53 41 -42 17 11 166 51 26 -42 25 31 0.60
167 31 10 -42 41 56 14 7 1.6 56 102 -52 167 40 3 -42 40 44 167 22 15 -42 43 8 168 2 19 -42 37 38 166 59 48 -42 46 4 0.60
167 39 38 -43 2 24 14 7 5.9 56 101 -52 167 48 35 -43 1 11 167 30 41 -43 3 37 168 10 56 -42 58 4 167 8 8 -43 6 35 0.60
167 48 6 -43 22 50 14 7 10.2 56 101 -52 167 57 5 -43 21 36 167 39 6 -43 24 4 168 19 32 -43 18 27 167 16 27 -43 27 4 0.60
167 56 33 -43 43 14 14 7 14.5 56 100 -51 168 5 34 -43 42 0 167 47 30 -43 44 29 168 28 8 -43 38 48 167 24 44 -43 47 31 0.60
168 4 58 -44 3 37 14 7 18.8 56 100 -51 168 14 2 -44 2 21 167 55 53 -44 4 52 168 36 42 -43 59 8 167 33 1 -44 7 56 0.60
168 13 23 -44 23 58 14 7 23.1 56 99 -51 168 22 30 -44 22 41 168 4 16 -44 25 13 168 45 16 -44 19 26 167 41 17 -44 28 19 0.60
168 21 48 -44 44 16 14 7 27.4 57 99 -50 168 30 57 -44 42 59 168 12 37 -44 45 33 168 53 50 -44 39 42 167 49 31 -44 48 41 0.60
168 30 11 -45 4 34 14 7 31.7 57 98 -50 168 39 23 -45 3 16 168 20 58 -45 5 51 169 2 23 -44 59 57 167 57 45 -45 9 1 0.60
168 38 34 -45 24 50 14 7 36.0 57 97 -50 168 47 49 -45 23 31 168 29 18 -45 26 8 169 10 56 -45 20 10 168 5 58 -45 29 20 0.60
168 46 57 -45 45 4 14 7 40.3 57 97 -49 168 56 14 -45 43 44 168 37 38 -45 46 23 169 19 28 -45 40 21 168 14 11 -45 49 37 0.60
168 55 19 -46 5 17 14 7 44.6 57 96 -49 169 4 39 -46 3 57 168 45 57 -46 6 36 169 28 1 -46 0 31 168 22 23 -46 9 52 0.60
169 3 41 -46 25 28 14 7 49.0 57 95 -49 169 13 4 -46 24 7 168 54 16 -46 26 49 169 36 33 -46 20 40 168 30 34 -46 30 7 0.60
169 12 2 -46 45 39 14 7 53.3 57 95 -48 169 21 29 -46 44 17 169 2 35 -46 47 0 169 45 5 -46 40 48 168 38 45 -46 50 20 0.60
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