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Updated: 2018 FEB 27, 17:16 UT
Event Rank : 87
(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 Mar 09 UT, the 87.6 km diameter asteroid (754) Malabar will occult a 11.5 mag star in the constellation Libra for observers along a fairly narrow path across Western Australia, from Albany a little east of Perth to Port Headland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.73 mag to 14.16 mag (the magnitude of the asteroid) for at most 7.6 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.
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
119 54 24 -13 0 0 18 40 57 72 52 -49 120 19 24 119 29 21 120 41 57 119 6 41 -0.25
119 49 51 -14 0 0 18 40 47 71 50 -49 120 14 58 119 24 41 120 37 37 119 1 54 -0.25
119 44 58 -15 0 0 18 40 38 70 48 -48 120 10 12 119 19 40 120 32 59 118 56 47 -0.25
119 39 44 -16 0 0 18 40 29 69 47 -48 120 5 7 119 14 19 120 28 1 118 51 17 -0.25
119 34 9 -17 0 0 18 40 19 69 45 -48 119 59 41 119 8 35 120 22 42 118 45 26 -0.25
119 28 13 -18 0 0 18 40 10 68 44 -47 119 53 54 119 2 29 120 17 3 118 39 11 -0.25
119 21 53 -19 0 0 18 40 1 67 42 -47 119 47 44 118 55 59 120 11 3 118 32 32 -0.25
119 15 11 -20 0 0 18 39 52 66 41 -47 119 41 12 118 49 6 120 4 40 118 25 29 -0.25
119 8 3 -21 0 0 18 39 43 65 40 -46 119 34 16 118 41 47 119 57 55 118 18 0 -0.25
119 0 31 -22 0 0 18 39 34 64 39 -46 119 26 56 118 34 3 119 50 45 118 10 5 -0.26
118 52 33 -23 0 0 18 39 25 63 38 -45 119 19 10 118 25 52 119 43 11 118 1 42 -0.26
118 44 7 -24 0 0 18 39 16 63 37 -45 119 10 58 118 17 12 119 35 11 117 52 50 -0.26
118 35 13 -25 0 0 18 39 7 62 36 -45 119 2 19 118 8 4 119 26 44 117 43 28 -0.26
118 25 50 -26 0 0 18 38 59 61 36 -44 118 53 10 117 58 25 119 17 49 117 33 36 -0.26
118 15 55 -27 0 0 18 38 50 60 35 -44 118 43 32 117 48 15 119 8 26 117 23 11 -0.26
118 5 29 -28 0 0 18 38 41 59 34 -43 118 33 23 117 37 32 118 58 31 117 12 12 -0.26
117 54 29 -29 0 0 18 38 33 58 34 -43 118 22 40 117 26 14 118 48 5 117 0 38 -0.26
117 42 54 -30 0 0 18 38 24 57 33 -42 118 11 24 117 14 20 118 37 6 116 48 27 -0.26
117 30 42 -31 0 0 18 38 16 56 33 -42 117 59 32 117 1 48 118 25 31 116 35 37 -0.26
117 17 52 -32 0 0 18 38 8 55 32 -41 117 47 2 116 48 36 118 13 20 116 22 6 -0.26
117 4 21 -33 0 0 18 38 0 54 32 -41 117 33 53 116 34 43 118 0 31 116 7 52 -0.26
116 50 7 -34 0 0 18 37 51 53 32 -40 117 20 3 116 20 6 117 47 1 115 52 54 -0.26
116 35 8 -35 0 0 18 37 43 52 31 -40 117 5 28 116 4 42 117 32 49 115 37 7 -0.26
116 19 22 -36 0 0 18 37 35 51 31 -39 116 50 8 115 48 30 117 17 52 115 20 31 -0.26
116 2 45 -37 0 0 18 37 28 50 31 -39 116 33 59 115 31 26 117 2 7 115 3 2 -0.26
115 45 16 -38 0 0 18 37 20 49 31 -38 116 16 58 115 13 27 116 45 32 114 44 37 -0.26
115 26 50 -39 0 0 18 37 12 48 31 -38 115 59 3 114 54 31 116 28 5 114 25 12 -0.26
115 7 25 -40 0 0 18 37 5 47 31 -37 115 40 10 114 34 33 116 9 41 114 4 45 -0.26
114 46 57 -41 0 0 18 36 57 46 31 -36 115 20 16 114 13 30 115 50 17 113 43 10 -0.26
Uncertainty in time = +/- 3 secs
Prediction of 2018 Feb 27.0
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