RASNZ Occultation Section - Chariklo Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (10199) CHARIKLO - 2013 Aug 08

Event Rank : 3

(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 2013 Aug 08 UT, the 258 km diameter asteroid (10199) Chariklo will occult a 14.9 mag star in the constellation Scorpius for observers along a path across possibly New Zealand.

In the case of an occultation, the combined light of the asteroid and the star will drop by 3.6 mag to 18.5 mag (the magnitude of the asteroid) for at most 22.4 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 :

Event Rank : 3
Date and approx. UT time of event : 2013 Aug 08, 07:25 - 2013 Aug 08, 07:34
(Refer to map(s) for your own location)
Magnitude of target star : 14.9
Magnitude drop [mag] : 3.6
Estimated maximum duration [s] : 22.4
Phase of moon, angular distance : 2 % sunlit, 101° distance
Sun : 117° distance
Rough path description : S Pacific

Data for the target star :

Name : S39a 1016561
Constellation : Scorpius
J2000 position with proper motion to date of event [h,m,s ; °,',"]: RA: 16 43 01.9940 DE: -39 13 06.111
Position source : mpos:UCAC4 pm:UCAC4
Standard error : RA,DE ["]: ( .093, .090 )
V mag [mag] : 14.9
B mag [mag] : 0.0
Remarks : (none)

Data for the minor planet :

Number, name : (10199) Chariklo
Approx. diameter [km] : 258
Approx. diameter [arcsec] : .025
Distance from Earth [AU] : 14.09300
Source of used astrometry : FASTT MPC (via Astdys)
Number of used observations : 540
Number of rejected observations : 7
Time covered by the observations : 1988 Nov 05 - 2011 Aug 29
1 sigma uncertainty ellipse (major, minor, PA) : 0.514, 0.059, 81°
Remarks : (none)
Orbital Elements for (10199) Chariklo :
Update computed by : Steve Preston, Medina, Washington, USA. (OrbFit).

The Occultation Path :

Approximate projected width [km] : 266
Uncertainty interval [path widths] : +/- 19.45 (1 sigma)
Uncertainty interval [seconds] : +/- 184.0 (1 sigma)
Uncertainty interval approx RA,DE ["] : (+/- .516 +/- .132) (1 sigma)
Uncertainty ellipse (major, minor, PA) : ( .522", .107", 81° ) (1 sigma)
Approx speed of asteroid's shadow [km/s]: 11.5074
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.
Path Co-ordinates :

                   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
   -178 35 59   - 6  0  0    7 34 25    57   181   -24 -177 17  0 -179 54 23  ... .. ..  129 43 21
   -178 10 19   - 7  0  0    7 34 16    58   182   -25 -176 50 59 -179 29  2  ... .. ..  130  5  1
   -177 44 11   - 8  0  0    7 34  7    59   183   -26 -176 24 29 -179  3 16  ... .. ..  130 25 59
   -177 17 34   - 9  0  0    7 33 58    60   183   -26 -175 57 28 -178 37  2  ... .. ..  130 46 16
   -176 50 27   -10  0  0    7 33 49    61   184   -27 -175 29 53 -178 10 20  ... .. ..  131  5 52

   -176 22 47   -11  0  0    7 33 39    62   185   -27 -175  1 45 -177 43  8  ... .. ..  131 24 47
   -175 54 34   -12  0  0    7 33 30    62   186   -28 -174 33  1 -177 15 25  ... .. ..  131 43  4
   -175 25 46   -13  0  0    7 33 20    63   187   -29 -174  3 39 -176 47  9  ... .. ..  132  0 41
   -174 56 21   -14  0  0    7 33 10    64   188   -29 -173 33 38 -176 18 19  ... .. ..  132 17 40
   -174 26 18   -15  0  0    7 33  0    65   189   -30 -173  2 57 -175 48 52  ... .. ..  132 34  2

                                                         Latitude   Latitude   Latitude   Latitude
   -174  0  0   -15 51 27    7 32 52    66   190   -30  -13  7 22  -18 31 15   .. .. ..   .. .. ..
   -173  0  0   -17 45 10    7 32 33    68   193   -32  -15  5 41  -20 20 46   .. .. ..   .. .. ..
   -172  0  0   -19 34  0    7 32 14    69   196   -33  -16 58 50  -22  5 36   .. .. ..   .. .. ..
   -171  0  0   -21 18  6    7 31 56    71   199   -34  -18 47  2  -23 45 55   .. .. ..   .. .. ..
   -170  0  0   -22 57 41    7 31 39    72   203   -35  -20 30 29  -25 21 54   .. .. ..   .. .. ..

   -169  0  0   -24 32 56    7 31 21    73   207   -36  -22  9 24  -26 53 43   .. .. ..   .. .. ..
   -168  0  0   -26  4  2    7 31  5    74   211   -37  -23 43 59  -28 21 34   .. .. ..   .. .. ..
   -167  0  0   -27 31 10    7 30 49    75   216   -37  -25 14 25  -29 45 35   .. .. ..   .. .. ..
   -166  0  0   -28 54 31    7 30 33    75   222   -38  -26 40 53  -31  5 58   .. .. ..   .. .. ..
   -165  0  0   -30 14 14    7 30 18    75   227   -39  -28  3 35  -32 22 51   .. .. ..   .. .. ..

   -164  0  0   -31 30 29    7 30  4    76   232   -40  -29 22 41  -33 36 25   .. .. ..   .. .. ..
   -163  0  0   -32 43 27    7 29 50    76   237   -40  -30 38 21  -34 46 47   .. .. ..   .. .. ..
   -162  0  0   -33 53 15    7 29 36    76   242   -41  -31 50 44  -35 54  8   .. .. ..   .. .. ..
   -161  0  0   -35  0  3    7 29 23    75   247   -42  -32 59 59  -36 58 35   .. .. ..   .. .. ..
   -160  0  0   -36  4  0    7 29 10    75   251   -42  -34  6 16  -38  0 15   .. .. ..   .. .. ..

   -159  0  0   -37  5 12    7 28 58    74   255   -43  -35  9 43  -38 59 18   .. .. ..   .. .. ..
   -158  0  0   -38  3 47    7 28 46    74   259   -43  -36 10 27  -39 55 50   .. .. ..   .. .. ..
   -157  0  0   -38 59 53    7 28 35    73   262   -44  -37  8 36  -40 49 57   .. .. ..   .. .. ..
   -156  0  0   -39 53 37    7 28 24    73   264   -44  -38  4 17  -41 41 47   .. .. ..   .. .. ..
   -155  0  0   -40 45  5    7 28 13    72   267   -44  -38 57 37  -42 31 26   .. .. ..   .. .. ..

   -154  0  0   -41 34 22    7 28  3    71   269   -45  -39 48 42  -43 18 59   .. .. ..   .. .. ..
   -153  0  0   -42 21 36    7 27 53    71   270   -45  -40 37 38  -44  4 33   .. .. ..   .. .. ..
   -152  0  0   -43  6 51    7 27 43    70   272   -46  -41 24 32  -44 48 12   .. .. ..   .. .. ..
   -151  0  0   -43 50 12    7 27 34    69   273   -46  -42  9 28  -45 30  2   .. .. ..   .. .. ..
   -150  0  0   -44 31 46    7 27 25    69   274   -46  -42 52 31  -46 10  7   .. .. ..   .. .. ..

   -149  0  0   -45 11 35    7 27 16    68   275   -47  -43 33 47  -46 48 32   .. .. ..   .. .. ..
   -148  0  0   -45 49 45    7 27  7    67   276   -47  -44 13 21  -47 25 21   .. .. ..   .. .. ..
   -147  0  0   -46 26 20    7 26 59    66   276   -47  -44 51 15  -48  0 39   .. .. ..   .. .. ..
   -146  0  0   -47  1 24    7 26 51    66   277   -47  -45 27 35  -48 34 28   .. .. ..   .. .. ..
   -145  0  0   -47 35  1    7 26 43    65   277   -47  -46  2 25  -49  6 53   .. .. ..   .. .. ..

   -144  0  0   -48  7 14    7 26 35    64   277   -48  -46 35 48  -49 37 58   .. .. ..   .. .. ..
   -143  0  0   -48 38  6    7 26 28    63   277   -48  -47  7 47  -50  7 44   .. .. ..   .. .. ..
   -142  0  0   -49  7 41    7 26 21    63   278   -48  -47 38 26  -50 36 16   .. .. ..   .. .. ..
   -141  0  0   -49 36  1    7 26 14    62   278   -48  -48  7 48  -51  3 36   .. .. ..   .. .. ..
   -140  0  0   -50  3 10    7 26  7    61   277   -48  -48 35 56  -51 29 48   .. .. ..   .. .. ..

   -139  0  0   -50 29 11    7 26  0    61   277   -48  -49  2 53  -51 54 52   .. .. ..   .. .. ..
   -138  0  0   -50 54  5    7 25 54    60   277   -49  -49 28 41  -52 18 53   .. .. ..   .. .. ..
   -137  0  0   -51 17 55    7 25 48    59   277   -49  -49 53 23  -52 41 52   .. .. ..   .. .. ..
   -136  0  0   -51 40 43    7 25 42    59   277   -49  -50 17  1  -53  3 52   .. .. ..   .. .. ..
   -135  0  0   -52  2 32    7 25 36    58   276   -49  -50 39 37  -53 24 54   .. .. ..   .. .. ..

   -134  0  0   -52 23 23    7 25 30    57   276   -49  -51  1 14  -53 45  1   .. .. ..   .. .. ..
   -133  0  0   -52 43 19    7 25 24    57   276   -49  -51 21 52  -54  4 14   .. .. ..   .. .. ..
   -132  0  0   -53  2 20    7 25 18    56   275   -49  -51 41 36  -54 22 35   .. .. ..   .. .. ..
   -131  0  0   -53 20 30    7 25 13    56   275   -49  -52  0 25  -54 40  6   .. .. ..   .. .. ..
   -130  0  0   -53 37 49    7 25  8    55   275   -49  -52 18 21  -54 56 47   .. .. ..   .. .. ..

   -129  0  0   -53 54 19    7 25  2    54   274   -49  -52 35 27  -55 12 42   .. .. ..   .. .. ..
   -128  0  0   -54 10  1    7 24 57    54   274   -49  -52 51 43  -55 27 51   .. .. ..   .. .. ..
   -127  0  0   -54 24 57    7 24 52    53   273   -49  -53  7 12  -55 42 14   .. .. ..   .. .. ..
   -126  0  0   -54 39  8    7 24 47    53   273   -49  -53 21 53  -55 55 55   .. .. ..   .. .. ..
   -125  0  0   -54 52 34    7 24 42    52   272   -49  -53 35 49  -56  8 53   .. .. ..   .. .. ..

Uncertainty in time = +/- 464 secs

Prediction of 2012 Jun  2.0

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