|
|
Updated: 2015 Sep 16, 02:09 UT
Event Rank : 7
(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 2015 Oct 21 UT, the 11 km diameter asteroid (27851) 1994 VG2 will occult a 10.3 mag star in the constellation Aries for observers along a narrow, large uncertainty path across New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.5 mag to 15.8 mag (the magnitude of the asteroid) for at most 0.9 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
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 1212-00868-1 by 27851 1994 VG2 on 2015 Oct 21
Centre Star Star Sun Path Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
166 34 40 -47 0 0 10 54 33 17 27 -28 166 29 34 166 39 47 164 58 37 168 10 2
167 24 38 -46 0 0 10 54 30 18 26 -29 167 19 38 167 29 38 165 50 41 168 57 57
168 13 0 -45 0 0 10 54 26 20 25 -30 168 8 6 168 17 54 166 41 1 169 44 25
168 59 56 -44 0 0 10 54 23 21 25 -31 168 55 8 169 4 44 167 29 48 170 29 34
169 45 32 -43 0 0 10 54 19 22 24 -33 169 40 49 169 50 14 168 17 7 171 13 29
170 29 54 -42 0 0 10 54 15 23 24 -34 170 25 16 170 34 31 169 3 7 171 56 16
171 13 8 -41 0 0 10 54 11 24 23 -35 171 8 35 171 17 41 169 47 52 172 38 1
171 55 19 -40 0 0 10 54 6 25 23 -36 171 50 51 171 59 48 170 31 30 173 18 49
172 36 33 -39 0 0 10 54 2 26 22 -37 172 32 9 172 40 57 171 14 5 173 58 43
173 16 53 -38 0 0 10 53 57 27 22 -38 173 12 33 173 21 13 171 55 41 174 37 49
173 56 24 -37 0 0 10 53 52 29 21 -39 173 52 8 174 0 40 172 36 24 175 16 9
174 35 9 -36 0 0 10 53 47 30 21 -40 174 30 57 174 39 21 173 16 17 175 53 48
175 13 12 -35 0 0 10 53 42 31 21 -42 175 9 3 175 17 21 173 55 24 176 30 49
175 50 36 -34 0 0 10 53 37 32 20 -43 175 46 30 175 54 42 174 33 48 177 7 14
Uncertainty in time = +/- 9 secs
Prediction of 2015 Sep 16.0
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]