|
|
Updated: 2017 Dec 15, 17:06 UT
Event Rank : 53
(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 2018 Jan 18 UT, the 72 km diameter asteroid (1345) Potomac will occult a 11.9 mag star in the constellation Taurus for observers along a significant uncertainty path across eastern West Australia, running from Eucla to Derby.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.52 mag to 15.40 mag (the magnitude of the asteroid) for at most 11.6 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 2UCAC 34398185 by 1345 Potomac on 2018 Jan 18
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
130 26 7 -35 27 1 13 7 43 41 325 -25 129 59 56 -35 27 20 130 52 25 -35 26 45 128 53 50 -35 28 16 131 59 43 -35 26 13 -0.27
129 34 58 -33 33 54 13 8 8 42 325 -26 129 9 31 -33 34 15 130 0 29 -33 33 35 128 5 16 -33 35 17 131 5 50 -33 32 55 -0.27
128 48 34 -31 44 6 13 8 32 44 325 -27 128 23 47 -31 44 29 129 13 27 -31 43 44 127 21 8 -31 45 36 130 17 5 -31 42 57 -0.27
128 6 13 -29 57 13 13 8 57 46 325 -28 127 42 0 -29 57 38 128 30 32 -29 56 49 126 40 46 -29 58 49 129 32 41 -29 55 57 -0.27
127 27 19 -28 12 56 13 9 22 48 325 -29 127 3 35 -28 13 22 127 51 7 -28 12 30 126 3 35 -28 14 37 128 51 58 -28 11 33 -0.27
126 51 23 -26 30 57 13 9 46 49 324 -30 126 28 6 -26 31 25 127 14 44 -26 30 31 125 29 12 -26 32 44 128 14 26 -26 29 30 -0.28
126 18 3 -24 51 4 13 10 11 51 323 -31 125 55 9 -24 51 33 126 41 0 -24 50 36 124 57 14 -24 52 54 127 39 40 -24 49 32 -0.28
125 47 0 -23 13 3 13 10 36 53 323 -32 125 24 27 -23 13 33 126 9 36 -23 12 34 124 27 24 -23 14 56 127 7 21 -23 11 27 -0.28
125 17 58 -21 36 43 13 11 1 54 322 -33 124 55 44 -21 37 14 125 40 16 -21 36 13 123 59 28 -21 38 39 126 37 12 -21 35 4 -0.28
124 50 46 -20 1 55 13 11 25 55 321 -34 124 28 48 -20 2 27 125 12 46 -20 1 25 123 33 13 -20 3 54 126 8 59 -20 0 13 -0.28
124 25 11 -18 28 30 13 11 50 57 320 -35 124 3 28 -18 29 3 124 46 57 -18 27 59 123 8 30 -18 30 31 125 42 31 -18 26 46 -0.28
124 1 4 -16 56 21 13 12 15 58 319 -35 123 39 35 -16 56 54 124 22 37 -16 55 50 122 45 10 -16 58 24 125 17 37 -16 54 34 -0.28
123 38 19 -15 25 21 13 12 40 59 318 -36 123 17 1 -15 25 55 123 59 40 -15 24 49 122 23 6 -15 27 25 124 54 9 -15 23 32 -0.28
123 16 47 -13 55 23 13 13 4 61 316 -37 122 55 40 -13 55 57 123 37 58 -13 54 50 122 2 11 -13 57 29 124 32 0 -13 53 32 -0.29
122 56 24 -12 26 22 13 13 29 62 315 -38 122 35 26 -12 26 56 123 17 25 -12 25 49 121 42 19 -12 28 29 124 11 4 -12 24 29 -0.29
122 37 4 -10 58 12 13 13 54 63 313 -39 122 16 14 -10 58 47 122 57 57 -10 57 39 121 23 27 -11 0 21 123 51 15 -10 56 18 -0.29
Uncertainty in time = +/- 15 secs
Prediction of 2017 Dec 15.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]