RASNZ Occultation Section - Klotho Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (97) KLOTHO - 2007 Feb 05

Event Rank : 99

(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 2007 Feb 05 UT, the 83 km diameter asteroid (97) Klotho will occult a 10.4 mag star in the constellation Orion for observers along beginning over Adelaide, moving in a northerly direction passing over eastern South Australia and western Queensland including directly over Mt Isa. The path then crosses Papua New Guinea passing very close to Wewak.

In the case of an occultation, the combined light of the asteroid and the star will drop by 1.0 mag to 10.9 mag (the magnitude of the asteroid) for at most 11.2 seconds.

This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, TMO astrometry for the asteroid kindly provided by Bill Owen, 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 : 99
Date and approx. UT time of event : 2007 Feb 05, 13:39 - 2007 Feb 15, 13:48
(Refer to map(s) for your own location)
Magnitude of target star : 10.4
Magnitude drop [mag] : 1.0
Estimated maximum duration [s] : 11.2
Phase of moon, angular distance : 90 % sunlit, 88° distance
Sun : 128° distance
Rough path description : Australia

Data for the target star :

Name : TYC 0714-00935-1
Constellation : Orion
J2000 position with proper motion to date of event [h,m,s ; °,',"]: RA: 05 42 09.5704 DE: +08 31 09.514
Position source : mpos:UCAC2 pm:UCAC2
Standard error : RA,DE ["]: ( .020, .019 )
V mag [mag] : 10.4
B mag [mag] : 11.4
Remarks : (none)

Data for the minor planet :

Number, name : (97) Klotho
Approx. diameter [km] : 83
Approx. diameter [arcsec] : .087
Distance from Earth [AU] : 1.31900
Source of used astrometry : FASTT TMO MPC (via Astdys)
Number of used observations : 967
Number of rejected observations : 132
Time covered by the observations : 1905 Nov 30 - 2006 Dec 21
1 sigma uncertainty ellipse (major, minor, PA) : 0.021, 0.012, 87°
Remarks : (none)
Orbital Elements for (97) Klotho :
Update computed by : Steve Preston, Medina, Washington, USA. (OrbFit).

The Occultation Path :

Approximate projected width [km] : 111
Uncertainty interval [path widths] : +/- 0.32 (1 sigma)
Uncertainty interval [seconds] : +/- 3.0 (1 sigma)
Uncertainty interval approx RA,DE ["] : (+/- .029 +/- .022) (1 sigma)
Uncertainty ellipse (major, minor, PA) : ( .029", .022", 88° ) (1 sigma)
Approx speed of asteroid's shadow [km/s]: 7.4087
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
    140 34 55   -43  0  0   13 38 31    30   319   -29  141 15 54  139 54 19  141 42 21  139 28 31
    140 18  6   -42  0  0   13 38 42    30   319   -30  140 58 18  139 38 17  141 24 13  139 12 58
    140  2 57   -41  0  0   13 38 52    31   319   -31  140 42 24  139 23 51  141  7 51  138 59  0
    139 49 22   -40  0  0   13 39  3    32   319   -31  140 28  8  139 10 57  140 53  8  138 46 32
    139 37 17   -39  0  0   13 39 13    33   319   -32  140 15 24  138 59 29  140 39 58  138 35 28

    139 26 35   -38  0  0   13 39 24    34   318   -33  140  4  6  138 49 23  140 28 17  138 25 44
    139 17 13   -37  0  0   13 39 36    35   318   -34  139 54 10  138 40 34  140 17 59  138 17 16
    139  9  7   -36  0  0   13 39 47    35   318   -35  139 45 33  138 32 59  140  9  2  138 10  1
    139  2 14   -35  0  0   13 39 59    36   317   -36  139 38 11  138 26 35  140  1 20  138  3 55
    138 56 31   -34  0  0   13 40 11    37   317   -37  139 32  0  138 21 19  139 54 52  137 58 56

    138 51 55   -33  0  0   13 40 23    38   316   -38  139 26 58  138 17  8  139 49 33  137 55  1
    138 48 23   -32  0  0   13 40 35    38   316   -39  139 23  3  138 14  0  139 45 22  137 52  7
    138 45 54   -31  0  0   13 40 48    39   315   -40  139 20 11  138 11 52  139 42 16  137 50 13
    138 44 24   -30  0  0   13 41  0    40   314   -40  139 18 21  138 10 43  139 40 13  137 49 17
    138 43 54   -29  0  0   13 41 13    40   314   -41  139 17 31  138 10 31  139 39 10  137 49 17

    138 44 20   -28  0  0   13 41 26    41   313   -42  139 17 40  138 11 15  139 39  8  137 50 12
    138 45 42   -27  0  0   13 41 39    42   312   -43  139 18 45  138 12 53  139 40  3  137 52  1
    138 47 59   -26  0  0   13 41 53    42   312   -44  139 20 47  138 15 25  139 41 55  137 54 41
    138 51  9   -25  0  0   13 42  6    43   311   -45  139 23 43  138 18 48  139 44 42  137 58 14
    138 55 11   -24  0  0   13 42 20    43   310   -46  139 27 34  138 23  3  139 48 24  138  2 37

    139  0  6   -23  0  0   13 42 34    44   309   -47  139 32 17  138 28  9  139 53  1  138  7 50
    139  5 52   -22  0  0   13 42 48    45   308   -48  139 37 53  138 34  6  139 58 30  138 13 52
    139 12 30   -21  0  0   13 43  2    45   307   -49  139 44 22  138 40 52  140  4 53  138 20 44
    139 19 58   -20  0  0   13 43 17    45   306   -50  139 51 42  138 48 27  140 12  8  138 28 25
    139 28 16   -19  0  0   13 43 31    46   305   -51  139 59 54  138 56 53  140 20 16  138 36 54

    139 37 26   -18  0  0   13 43 46    46   304   -52  140  8 58  139  6  8  140 29 16  138 46 13
    139 47 26   -17  0  0   13 44  1    47   303   -53  140 18 53  139 16 12  140 39  9  138 56 20
    139 58 17   -16  0  0   13 44 16    47   302   -54  140 29 41  139 27  7  140 49 54  139  7 17
    140  9 59   -15  0  0   13 44 31    47   301   -55  140 41 21  139 38 51  141  1 33  139 19  3
    140 22 33   -14  0  0   13 44 46    48   300   -56  140 53 54  139 51 27  141 14  5  139 31 40

    140 36  0   -13  0  0   13 45  1    48   299   -57  141  7 21  140  4 54  141 27 32  139 45  7
    140 50 20   -12  0  0   13 45 17    48   297   -58  141 21 41  140 19 13  141 41 54  139 59 25
    141  5 34   -11  0  0   13 45 32    48   296   -59  141 36 58  140 34 25  141 57 12  140 14 36
    141 21 43   -10  0  0   13 45 48    48   295   -60  141 53 10  140 50 31  142 13 27  140 30 40
    141 38 49   - 9  0  0   13 46  4    48   294   -61  142 10 21  141  7 32  142 30 40  140 47 39

    141 56 52   - 8  0  0   13 46 20    49   293   -62  142 28 30  141 25 30  142 48 53  141  5 33
    142 15 54   - 7  0  0   13 46 36    49   291   -63  142 47 39  141 44 25  143  8  7  141 24 25
    142 35 58   - 6  0  0   13 46 52    48   290   -64  143  7 51  142  4 21  143 28 25  141 44 15
    142 57  4   - 5  0  0   13 47  8    48   289   -65  143 29  8  142 25 18  143 49 48  142  5  6
    143 19 15   - 4  0  0   13 47 24    48   288   -66  143 51 30  142 47 18  144 12 18  142 27  0

    143 42 34   - 3  0  0   13 47 40    48   286   -67  144 15  1  143 10 24  144 35 57  142 49 58
    144  7  2   - 2  0  0   13 47 57    48   285   -68  144 39 44  143 34 39  145  0 49  143 14  4
    144 32 43   - 1  0  0   13 48 13    48   284   -69  145  5 41  144  0  4  145 26 57  143 39 20
    144 59 39     0  0  0   13 48 30    47   283   -71  145 32 55  144 26 43  145 54 23  144  5 48
    145 27 55     1  0  0   13 48 47    47   281   -72  146  1 30  144 54 39  146 23 12  144 33 33

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