RASNZ Occultation Section - 2010WZ71 Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (0) 2010WZ71 - 2012 Feb 02

Event Rank : 0

(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 2012 Feb 02 UT, the 5 km diameter asteroid (0) 2010 WZ71 will occult a 13.6 mag star in the constellation Corvus for observers along a very uncertain path possibly across Australia.

In the case of an occultation, the combined light of the asteroid and the star will drop by 4.7 mag to 18.3 mag (the magnitude of the asteroid) for at most 3.1 seconds.

This update is based on 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 : 0
Date and approx. UT time of event : 2012 Feb 02, 17:04 - 2012 Feb 02, 18:43
(Refer to map(s) for your own location)
Magnitude of target star : 13.6
Magnitude drop [mag] : 4.7
Estimated maximum duration [s] : 3.1
Phase of moon, angular distance : 73 % sunlit, 117° distance
Sun : 121° distance
Rough path description : Possibly Australia, Indonesia, S Asia

Data for the target star :

Name : UCAC2 23373933
Constellation : Corvus
J2000 position with proper motion to date of event [h,m,s ; °,',"]: RA: 12 04 09.1588 DE: -21 16 36.459
Position source : mpos:UCAC2 pm:UCAC2
Standard error : RA,DE ["]: ( .057, .056 )
V mag [mag] : 13.6
B mag [mag] : 0.0
Remarks : (none)

Data for the minor planet :

Number, name : (0) 2010WZ71
Approx. diameter [km] : 5
Approx. diameter [arcsec] : .003
Distance from Earth [AU] : 2.35600
Source of used astrometry : MPC (via Astdys)
Number of used observations : 29
Number of rejected observations : 0
Time covered by the observations : 2009 Sep 29 - 2011 Jan 05
1 sigma uncertainty ellipse (major, minor, PA) : 21.601, 0.860, 96°
Remarks : (none)
Orbital Elements for (0) 2010WZ71 :
Update computed by : Steve Preston, Medina, Washington, USA. (OrbFit).

The Occultation Path :

Approximate projected width [km] : 5
Uncertainty interval [path widths] : +/- 7115.22 (1 sigma)
Uncertainty interval [seconds] : +/- 2508.1 (1 sigma)
Uncertainty interval approx RA,DE ["] : (+/- 21.483 +/- 2.412) (1 sigma)
Uncertainty ellipse (major, minor, PA) : ( 21.601", .862", 96° ) (1 sigma)
Approx speed of asteroid's shadow [km/s]: 1.5766
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
    176 54 28    60  0  0   17  3 33     6   202   -25  176 51 34  176 57 22  ... .. ..  ... .. ..
    176  8  5    59  0  0   17  3 42     8   202   -25  176  5 16  176 10 53  ... .. ..  ... .. ..
    175 24 31    58  0  0   17  3 52     9   201   -26  175 21 48  175 27 14  ... .. ..  ... .. ..
    174 43 29    57  0  0   17  4  4    10   201   -26  174 40 51  174 46  7  ... .. ..  ... .. ..
    174  4 41    56  0  0   17  4 18    11   200   -27  174  2  8  174  7 15  ... .. ..  ... .. ..

    173 27 55    55  0  0   17  4 32    12   200   -27  173 25 26  173 30 24  ... .. ..  ... .. ..
    172 52 57    54  0  0   17  4 48    13   199   -28  172 50 32  172 55 22  ... .. ..  ... .. ..
    172 19 37    53  0  0   17  5  5    14   199   -28  172 17 16  172 21 58  ... .. ..  ... .. ..
    171 47 45    52  0  0   17  5 23    15   199   -29  171 45 27  171 50  3  ... .. ..  ... .. ..
    171 17 12    51  0  0   17  5 43    16   198   -29  171 14 58  171 19 27  ... .. ..  ... .. ..

    170 47 52    50  0  0   17  6  3    17   198   -29  170 45 40  170 50  3  ... .. ..  ... .. ..
    170 19 37    49  0  0   17  6 25    18   198   -30  170 17 28  170 21 46  ... .. ..  ... .. ..
    169 52 21    48  0  0   17  6 49    19   197   -30  169 50 15  169 54 27  ... .. ..  ... .. ..
    169 25 59    47  0  0   17  7 13    20   197   -31  169 23 56  169 28  3  ... .. ..  ... .. ..
    169  0 27    46  0  0   17  7 39    21   197   -31  168 58 26  169  2 28  ... .. ..  ... .. ..

    168 35 39    45  0  0   17  8  5    22   197   -31  168 33 40  168 37 38  ... .. ..  ... .. ..
    168 11 31    44  0  0   17  8 33    23   197   -32  168  9 35  168 13 28  ... .. ..  ... .. ..
    167 48  1    43  0  0   17  9  2    24   197   -32  167 46  7  167 49 56  ... .. ..  ... .. ..
    167 25  5    42  0  0   17  9 32    25   196   -32  167 23 12  167 26 58  ... .. ..  ... .. ..
    167  2 40    41  0  0   17 10  4    26   196   -33  167  0 49  167  4 31  ... .. ..  ... .. ..

    166 40 43    40  0  0   17 10 36    27   196   -33  166 38 54  166 42 33  ... .. ..  ... .. ..
    166 19 13    39  0  0   17 11 10    28   196   -33  166 17 25  166 21  0  ... .. ..  ... .. ..
    165 58  6    38  0  0   17 11 44    29   196   -33  165 56 19  165 59 52  ... .. ..  ... .. ..
    165 37 20    37  0  0   17 12 20    30   196   -34  165 35 35  165 39  5  ... .. ..  ... .. ..
    165 16 55    36  0  0   17 12 57    31   196   -34  165 15 11  165 18 38  ... .. ..  ... .. ..

    164 56 47    35  0  0   17 13 34    32   196   -34  164 55  5  164 58 30  ... .. ..  ... .. ..
    164 36 57    34  0  0   17 14 13    33   196   -34  164 35 16  164 38 38  ... .. ..  ... .. ..
    164 17 22    33  0  0   17 14 53    34   196   -34  164 15 42  164 19  2  ... .. ..  ... .. ..
    163 58  1    32  0  0   17 15 34    35   196   -34  163 56 22  163 59 39  ... .. ..  ... .. ..
    163 38 52    31  0  0   17 16 16    36   196   -35  163 37 15  163 40 30  ... .. ..  ... .. ..

    163 19 56    30  0  0   17 16 59    37   196   -35  163 18 19  163 21 33  ... .. ..  ... .. ..
    163  1 10    29  0  0   17 17 42    38   196   -35  162 59 35  163  2 46  ... .. ..  ... .. ..
    162 42 35    28  0  0   17 18 27    39   196   -35  162 41  0  162 44 10  ... .. ..  ... .. ..
    162 24  8    27  0  0   17 19 13    40   196   -35  162 22 34  162 25 43  ... .. ..  ... .. ..
    162  5 51    26  0  0   17 20  0    41   196   -35  162  4 18  162  7 24  ... .. ..  ... .. ..

    161 47 41    25  0  0   17 20 47    42   197   -35  161 46  8  161 49 13  ... .. ..  ... .. ..
    161 29 38    24  0  0   17 21 36    43   197   -35  161 28  7  161 31 10  ... .. ..  ... .. ..
    161 11 42    23  0  0   17 22 25    44   197   -35  161 10 11  161 13 14  ... .. ..  ... .. ..
    160 53 53    22  0  0   17 23 15    45   197   -35  160 52 23  160 55 23  ... .. ..  ... .. ..
    160 36  9    21  0  0   17 24  6    46   197   -35  160 34 40  160 37 39  ... .. ..  ... .. ..

    160 18 31    20  0  0   17 24 58    47   197   -35  160 17  2  160 20  1  ... .. ..  ... .. ..
    160  0 59    19  0  0   17 25 51    48   198   -35  159 59 30  160  2 27  ... .. ..  ... .. ..
    159 43 31    18  0  0   17 26 44    49   198   -35  159 42  3  159 44 59  ... .. ..  ... .. ..
    159 26  8    17  0  0   17 27 38    50   198   -35  159 24 40  159 27 36  ... .. ..  ... .. ..
    159  8 49    16  0  0   17 28 33    51   198   -35  159  7 22  159 10 17  ... .. ..  ... .. ..

    158 51 35    15  0  0   17 29 29    52   199   -35  158 50  8  158 53  2  ... .. ..  ... .. ..
    158 34 26    14  0  0   17 30 26    53   199   -34  158 32 59  158 35 52  ... .. ..  ... .. ..
    158 17 20    13  0  0   17 31 23    54   200   -34  158 15 54  158 18 46  ... .. ..  ... .. ..
    158  0 19    12  0  0   17 32 21    55   200   -34  157 58 53  158  1 44  ... .. ..  ... .. ..
    157 43 21    11  0  0   17 33 19    56   200   -34  157 41 56  157 44 47  ... .. ..  ... .. ..

    157 26 28    10  0  0   17 34 19    57   201   -34  157 25  3  157 27 53  ... .. ..  ... .. ..
    157  9 39     9  0  0   17 35 19    57   201   -34  157  8 14  157 11  4  ... .. ..  ... .. ..
    156 52 54     8  0  0   17 36 19    58   202   -33  156 51 29  156 54 19  ... .. ..  ... .. ..
    156 36 14     7  0  0   17 37 20    59   202   -33  156 34 49  156 37 39  ... .. ..  ... .. ..
    156 19 38     6  0  0   17 38 22    60   203   -33  156 18 13  156 21  2  ... .. ..  ... .. ..

    156  3  6     5  0  0   17 39 24    61   204   -33  156  1 42  156  4 31  ... .. ..  ... .. ..
    155 46 40     4  0  0   17 40 27    62   204   -32  155 45 15  155 48  4  ... .. ..  ... .. ..
    155 30 18     3  0  0   17 41 31    63   205   -32  155 28 54  155 31 42  ... .. ..  ... .. ..
    155 14  1     2  0  0   17 42 35    64   206   -32  155 12 37  155 15 25  ... .. ..  ... .. ..
    154 57 50     1  0  0   17 43 39    65   207   -31  154 56 26  154 59 14  ... .. ..  ... .. ..

    154 41 44     0  0  0   17 44 44    66   208   -31  154 40 20  154 43  8  ... .. ..  ... .. ..
    154 25 44   - 1  0  0   17 45 50    67   209   -31  154 24 20  154 27  9  ... .. ..  ... .. ..
    154  9 51   - 2  0  0   17 46 55    67   210   -30  154  8 27  154 11 15  ... .. ..  ... .. ..
    153 54  4   - 3  0  0   17 48  2    68   212   -30  153 52 40  153 55 28  ... .. ..  ... .. ..
    153 38 24   - 4  0  0   17 49  8    69   213   -30  153 36 59  153 39 48  ... .. ..  ... .. ..

    153 22 51   - 5  0  0   17 50 15    70   214   -29  153 21 26  153 24 15  ... .. ..  ... .. ..
    153  7 25   - 6  0  0   17 51 23    71   216   -29  153  6  1  153  8 50  ... .. ..  ... .. ..
    152 52  8   - 7  0  0   17 52 31    71   218   -28  152 50 43  152 53 33  ... .. ..  ... .. ..
    152 36 59   - 8  0  0   17 53 39    72   220   -28  152 35 34  152 38 24  ... .. ..  ... .. ..
    152 22  0   - 9  0  0   17 54 47    73   222   -27  152 20 34  152 23 25  ... .. ..  ... .. ..

    152  7  9   -10  0  0   17 55 56    74   224   -27  152  5 44  152  8 35  ... .. ..  ... .. ..
    151 52 29   -11  0  0   17 57  5    74   227   -27  151 51  3  151 53 54  ... .. ..  ... .. ..
    151 37 59   -12  0  0   17 58 14    75   230   -26  151 36 33  151 39 25  ... .. ..  ... .. ..
    151 23 40   -13  0  0   17 59 23    75   233   -26  151 22 13  151 25  6  ... .. ..  ... .. ..
    151  9 32   -14  0  0   18  0 33    76   236   -25  151  8  6  151 10 59  ... .. ..  ... .. ..

    150 55 37   -15  0  0   18  1 43    76   240   -25  150 54 10  150 57  4  ... .. ..  ... .. ..
    150 41 55   -16  0  0   18  2 53    77   243   -24  150 40 28  150 43 23  ... .. ..  ... .. ..
    150 28 26   -17  0  0   18  4  3    77   248   -24  150 26 58  150 29 54  ... .. ..  ... .. ..
    150 15 12   -18  0  0   18  5 13    77   252   -23  150 13 44  150 16 41  ... .. ..  ... .. ..
    150  2 13   -19  0  0   18  6 23    78   256   -23  150  0 44  150  3 42  ... .. ..  ... .. ..

    149 49 29   -20  0  0   18  7 34    78   261   -22  149 48  0  149 50 59  ... .. ..  ... .. ..
    149 37  3   -21  0  0   18  8 44    78   265   -21  149 35 33  149 38 33  ... .. ..  ... .. ..
    149 24 53   -22  0  0   18  9 54    78   270   -21  149 23 23  149 26 24  ... .. ..  ... .. ..
    149 13  3   -23  0  0   18 11  5    78   275   -20  149 11 31  149 14 34  ... .. ..  ... .. ..
    149  1 31   -24  0  0   18 12 15    77   279   -20  148 59 59  149  3  3  ... .. ..  ... .. ..

    148 50 20   -25  0  0   18 13 26    77   283   -19  148 48 48  148 51 53  ... .. ..  ... .. ..
    148 39 31   -26  0  0   18 14 36    77   287   -19  148 37 57  148 41  4  ... .. ..  ... .. ..
    148 29  4   -27  0  0   18 15 47    76   291   -18  148 27 29  148 30 38  ... .. ..  ... .. ..
    148 19  1   -28  0  0   18 16 57    76   295   -17  148 17 25  148 20 36  ... .. ..  ... .. ..
    148  9 22   -29  0  0   18 18  7    75   298   -17  148  7 46  148 10 58  ... .. ..  ... .. ..

    148  0 11   -30  0  0   18 19 17    75   301   -16  147 58 34  148  1 47  ... .. ..  ... .. ..
    147 51 26   -31  0  0   18 20 27    74   303   -16  147 49 48  147 53  4  ... .. ..  ... .. ..
    147 43 12   -32  0  0   18 21 37    73   306   -15  147 41 33  147 44 51  ... .. ..  ... .. ..
    147 35 27   -33  0  0   18 22 46    73   308   -14  147 33 47  147 37  8  ... .. ..  ... .. ..
    147 28 16   -34  0  0   18 23 56    72   310   -14  147 26 35  147 29 57  ... .. ..  ... .. ..

    147 21 38   -35  0  0   18 25  5    71   312   -13  147 19 56  147 23 21  ... .. ..  ... .. ..
    147 15 37   -36  0  0   18 26 14    70   314   -12  147 13 53  147 17 21  ... .. ..  ... .. ..
    147 10 14   -37  0  0   18 27 22    69   315   -12  147  8 29  147 11 59  ... .. ..  ... .. ..
    147  5 31   -38  0  0   18 28 31    69   317   -11  147  3 45  147  7 18  ... .. ..  ... .. ..
    147  1 31   -39  0  0   18 29 39    68   318   -10  146 59 43  147  3 19  ... .. ..  ... .. ..

    146 58 17   -40  0  0   18 30 47    67   319   -10  146 56 27  147  0  6  ... .. ..  ... .. ..
    146 55 50   -41  0  0   18 31 54    66   320    -9  146 53 58  146 57 41  ... .. ..  ... .. ..
    146 54 14   -42  0  0   18 33  1    65   321    -8  146 52 20  146 56  7  ... .. ..  ... .. ..
    146 53 31   -43  0  0   18 34  7    64   322    -8  146 51 36  146 55 27  ... .. ..  ... .. ..
    146 53 47   -44  0  0   18 35 14    63   323    -7  146 51 50  146 55 44  ... .. ..  ... .. ..

    146 55  3   -45  0  0   18 36 20    62   323    -6  146 53  4  146 57  3  ... .. ..  ... .. ..
    146 57 25   -46  0  0   18 37 25    61   324    -6  146 55 24  146 59 26  ... .. ..  ... .. ..
    147  0 56   -47  0  0   18 38 30    61   324    -5  146 58 53  147  3  0  ... .. ..  ... .. ..
    147  5 42   -48  0  0   18 39 34    60   325    -4  147  3 36  147  7 49  ... .. ..  ... .. ..
    147 11 48   -49  0  0   18 40 38    59   325    -3  147  9 39  147 13 57  ... .. ..  ... .. ..

    147 19 19   -50  0  0   18 41 42    58   325    -3  147 17  8  147 21 31  ... .. ..  ... .. ..
    147 28 23   -51  0  0   18 42 45    57   326    -2  147 26  8  147 30 38  ... .. ..  ... .. ..
    147 39  7   -52  0  0   18 43 47    56   326    -1  147 36 48  147 41 25  ... .. ..  ... .. ..
    147 51 38   -53  0  0   18 44 49    55   326     0  147 49 16  147 53 59  ... .. ..  ... .. ..

Uncertainty in time = +/- 23411 secs

Prediction of 2012 Jan 26.0

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