RASNZ Occultation Section - Tokio Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (498) TOKIO - 2004 FEB 17

[Edwin Goffin's Prediction + Finder Charts]

UPDATE: 2004 FEB 08, 02:17 UT

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 the time for your location)

On 2004 Feb 17 UT, the 82 km diameter asteroid (498) Tokio will occult a 7.3 mag star in the constellation Virgo for observers along a path across New Zealand.

In the case of an occultation, the combined light of the asteroid and the star will drop by 6.6 mag to 13.9 mag (the magnitude of the asteroid) for at most 14.1 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: Hipparcos .

Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/

EVENT DETAILS SUMMARY :

Event Rank : 96
(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).
Date and approx. UT time of event : 2004 Feb 17, 16:07 - 2004 Feb 17, 16:41 UT
(Refer to map(s) for your own location)
Magnitude of target star : 7.3
Magnitude drop [mag] : 6.6
Estimated maximum duration [s] : 14.1
Phase of moon, angular distance : 9 % sunlit, 95° distance
Sun : 128° distance
Rough path description : New Zealand, Japan, Russia

Data for the target star :

Name : HIP 65791
Constellation : Virgo
J2000 position [h,m,s ; °,',"]: RA: 13 29 13.6155 DE: +03 52 17.097
Position source : Hipparcos
Standard error : RA,DE ["]: ( .011, .010 )
V mag [mag] : 7.3
Remarks : (none)

Data for the minor planet :

Number, name : (498) Tokio
Approx. diameter [km] : 82
Approx. diameter [arcsec] : .046
Source of used astrometry : FASTT TMO MPC (via Astdys)
Number of used observations : 556
Number of rejected observations : 39
Time covered by the observations : 1900 Mar 06 - 2004 Feb 07
1 sigma uncertainty ellipse (major, minor, PA) : 0.017, 0.012, 113°
Remarks : (none)
Update computed by : Steve Preston, Medina, Washington, USA. (OrbFit).

The Occultation Path :

Approximate projected width [km] : 85
Uncertainty interval [path widths] : +/- 0.41 (1 sigma)
Uncertainty interval [seconds] : +/- 5.3 (1 sigma)
Uncertainty interval approx RA,DE ["] : (+/- .020 +/- .016) (1 sigma)
Uncertainty ellipse (major, minor, PA) : ( .020", .016", 106° ) (1 sigma)
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
    179 47  7   -68  0  0   16  7 24    18   353     0  ... .. ..  178 44 26  ... .. ..  177 53  5
    179 13 48   -67  0  0   16  7 30    19   354    -1 -179 46  2  178 13 43 -178 56 37  177 24 29
    178 42 14   -66  0  0   16  7 37    20   354    -2  179 40  1  177 44 31 -179 32 32  176 57 13
    178 12 11   -65  0  0   16  7 44    21   355    -2  179  7 48  177 16 38  179 53 26  176 31  7
    177 43 28   -64  0  0   16  7 52    22   355    -3  178 37  4  176 49 54  179 21  4  176  6  0

    177 15 54   -63  0  0   16  7 59    23   356    -4  178  7 39  176 24 10  178 50  8  175 41 46
    176 49 21   -62  0  0   16  8  7    24   356    -4  177 39 24  175 59 18  178 20 29  175 18 17
    176 23 42   -61  0  0   16  8 16    25   357    -5  177 12 11  175 35 14  177 51 58  174 55 30
    175 58 51   -60  0  0   16  8 25    26   357    -6  176 45 52  175 11 50  177 24 27  174 33 17
    175 34 42   -59  0  0   16  8 34    27   357    -7  176 20 22  174 49  2  176 57 49  174 11 36

    175 11 10   -58  0  0   16  8 43    28   358    -7  175 55 34  174 26 47  176 31 59  173 50 23
    174 48 12   -57  0  0   16  8 53    29   358    -8  175 31 25  174  4 59  176  6 52  173 29 33
    174 25 44   -56  0  0   16  9  3    30   358    -9  175  7 50  173 43 37  175 42 22  173  9  5
    174  3 42   -55  0  0   16  9 13    31   359   -10  174 44 46  173 22 37  175 18 27  172 48 56
    173 42  3   -54  0  0   16  9 23    32   359   -11  174 22  9  173  1 56  174 55  1  172 29  3

    173 20 44   -53  0  0   16  9 34    33   360   -11  173 59 55  172 41 33  174 32  3  172  9 24
    172 59 45   -52  0  0   16  9 46    34   360   -12  173 38  4  172 21 25  174  9 29  171 49 58
    172 39  1   -51  0  0   16  9 57    35     0   -13  173 16 32  172  1 30  173 47 17  171 30 43
    172 18 32   -50  0  0   16 10  9    36     1   -14  172 55 17  171 41 46  173 25 24  171 11 37
    171 58 15   -49  0  0   16 10 21    37     1   -14  172 34 17  171 22 13  173  3 49  170 52 39

    171 38 10   -48  0  0   16 10 33    38     1   -15  172 13 30  171  2 48  172 42 28  170 33 48
    171 18 14   -47  0  0   16 10 46    39     2   -16  171 52 55  170 43 31  172 21 22  170 15  2
    170 58 26   -46  0  0   16 10 59    40     2   -17  171 32 31  170 24 19  172  0 27  169 56 20
    170 38 45   -45  0  0   16 11 12    41     3   -17  171 12 15  170  5 13  171 39 43  169 37 43
    170 19 10   -44  0  0   16 11 25    42     3   -18  170 52  8  169 46 11  171 19  9  169 19  7

    169 59 40   -43  0  0   16 11 39    43     3   -19  170 32  6  169 27 12  170 58 42  169  0 34
    169 40 14   -42  0  0   16 11 53    44     4   -20  170 12 11  169  8 15  170 38 22  168 42  1
    169 20 51   -41  0  0   16 12  7    45     4   -20  169 52 20  168 49 20  170 18  8  168 23 29
    169  1 30   -40  0  0   16 12 21    46     5   -21  169 32 32  168 30 26  169 57 58  168  4 56
    168 42 10   -39  0  0   16 12 36    47     5   -22  169 12 47  168 11 31  169 37 53  167 46 23

    168 22 51   -38  0  0   16 12 51    48     6   -23  168 53  4  167 52 36  169 17 50  167 27 47
    168  3 32   -37  0  0   16 13  6    49     6   -24  168 33 23  167 33 40  168 57 50  167  9  9
    167 44 12   -36  0  0   16 13 21    50     7   -24  168 13 41  167 14 42  168 37 51  166 50 29
    167 24 51   -35  0  0   16 13 37    51     7   -25  167 54  0  166 55 41  168 17 53  166 31 45
    167  5 28   -34  0  0   16 13 53    52     8   -26  167 34 18  166 36 38  167 57 54  166 12 58

    166 46  3   -33  0  0   16 14  9    53     8   -27  167 14 34  166 17 31  167 37 55  165 54  6
    166 26 35   -32  0  0   16 14 25    54     9   -27  166 54 48  165 58 20  167 17 55  165 35  9
    166  7  3   -31  0  0   16 14 41    55    10   -28  166 35  0  165 39  5  166 57 53  165 16  8
    165 47 27   -30  0  0   16 14 58    56    10   -29  166 15  8  165 19 45  166 37 49  164 57  0
    165 27 47   -29  0  0   16 15 15    57    11   -30  165 55 13  165  0 19  166 17 41  164 37 47

    165  8  2   -28  0  0   16 15 32    58    12   -31  165 35 14  164 40 48  165 57 30  164 18 27
    164 48 11   -27  0  0   16 15 49    59    13   -31  165 15 10  164 21 11  165 37 15  163 59  1
    164 28 15   -26  0  0   16 16  6    60    14   -32  164 55  0  164  1 27  165 16 56  163 39 27
    164  8 12   -25  0  0   16 16 24    60    15   -33  164 34 46  163 41 36  164 56 32  163 19 46
    163 48  2   -24  0  0   16 16 42    61    16   -34  164 14 25  163 21 37  164 36  2  162 59 56

    163 27 45   -23  0  0   16 16 59    62    17   -34  163 53 58  163  1 31  164 15 26  162 39 59
    163  7 21   -22  0  0   16 17 18    63    18   -35  163 33 24  162 41 16  163 54 44  162 19 52
    162 46 48   -21  0  0   16 17 36    64    19   -36  163 12 42  162 20 53  163 33 54  161 59 36
    162 26  8   -20  0  0   16 17 54    65    20   -37  162 51 52  162  0 21  163 12 58  161 39 11
    162  5 18   -19  0  0   16 18 13    66    22   -37  162 30 55  161 39 39  162 51 54  161 18 35

    161 44 19   -18  0  0   16 18 31    66    23   -38  162  9 48  161 18 47  162 30 41  160 57 50
    161 23 10   -17  0  0   16 18 50    67    25   -39  161 48 33  160 57 45  162  9 20  160 36 53
    161  1 51   -16  0  0   16 19  9    68    26   -40  161 27  7  160 36 32  161 47 49  160 15 45
    160 40 21   -15  0  0   16 19 28    69    28   -40  161  5 32  160 15  8  161 26  9  159 54 26
    160 18 40   -14  0  0   16 19 47    70    30   -41  160 43 46  159 53 32  161  4 19  159 32 54

    159 56 48   -13  0  0   16 20  6    70    32   -42  160 21 49  159 31 44  160 42 19  159 11 10
    159 34 43   -12  0  0   16 20 25    71    35   -43  159 59 41  159  9 44  160 20  7  158 49 13
    159 12 26   -11  0  0   16 20 45    72    37   -43  159 37 20  158 47 30  159 57 43  158 27  2
    158 49 56   -10  0  0   16 21  4    72    40   -44  159 14 47  158 25  3  159 35  8  158  4 37
    158 27 13   - 9  0  0   16 21 24    73    43   -45  158 52  1  158  2 22  159 12 20  157 41 58

    158  4 15   - 8  0  0   16 21 44    73    46   -46  158 29  1  157 39 26  158 49 18  157 19  4
    157 41  3   - 7  0  0   16 22  3    74    49   -46  158  5 47  157 16 15  158 26  3  156 55 54
    157 17 35   - 6  0  0   16 22 23    74    52   -47  157 42 19  156 52 49  158  2 34  156 32 28
    156 53 51   - 5  0  0   16 22 43    74    56   -48  157 18 35  156 29  6  157 38 49  156  8 45
    156 29 52   - 4  0  0   16 23  3    75    59   -48  156 54 35  156  5  5  157 14 50  155 44 45

    156  5 35   - 3  0  0   16 23 23    75    63   -49  156 30 19  155 40 48  156 50 34  155 20 27
    155 41  0   - 2  0  0   16 23 43    75    67   -50  156  5 45  155 16 12  156 26  1  154 55 50
    155 16  6   - 1  0  0   16 24  3    75    71   -50  155 40 53  154 51 17  156  1 10  154 30 53
    154 50 54     0  0  0   16 24 23    75    75   -51  155 15 43  154 26  2  155 36  2  154  5 36
    154 25 21     1  0  0   16 24 43    75    79   -52  154 50 13  154  0 27  155 10 34  153 39 59

    153 59 28     2  0  0   16 25  3    75    83   -52  154 24 23  153 34 30  154 44 46  153 13 59
    153 33 13     3  0  0   16 25 24    75    86   -53  153 58 11  153  8 11  154 18 38  152 47 37
    153  6 35     4  0  0   16 25 44    74    90   -53  153 31 38  152 41 29  153 52  8  152 20 51
    152 39 34     5  0  0   16 26  4    74    93   -54  153  4 42  152 14 22  153 25 16  151 53 41
    152 12  8     6  0  0   16 26 24    73    97   -55  152 37 21  151 46 51  152 58  0  151 26  5

    151 44 16     7  0  0   16 26 44    73   100   -55  152  9 36  151 18 53  152 30 19  150 58  2
    151 15 58     8  0  0   16 27  4    72   102   -56  151 41 25  150 50 28  152  2 13  150 29 31
    150 47 12     9  0  0   16 27 24    72   105   -56  151 12 46  150 21 35  151 33 41  150  0 31
    150 17 57    10  0  0   16 27 45    71   107   -57  150 43 39  149 52 12  151  4 40  149 31  1
    149 48 12    11  0  0   16 28  5    70   110   -57  150 14  2  149 22 17  150 35 10  149  1  0

    149 17 54    12  0  0   16 28 25    70   112   -58  149 43 54  148 51 50  150  5 10  148 30 25

                                                         Latitude   Latitude   Latitude   Latitude
    148  0  0    14 29 24   16 29 14    68   116   -59   15 18 49   13 39 38   15 59  7   12 58 34
    147  0  0    16 19 44   16 29 51    66   119   -60   17  8  4   15 31  6   17 47 29   14 50 58
    146  0  0    18  6  3   16 30 26    64   121   -60   18 53 20   17 18 29   19 31 54   16 39 15
    145  0  0    19 48 25   16 30 59    63   123   -61   20 34 42   19  1 53   21 12 28   18 23 30
    144  0  0    21 26 57   16 31 31    61   124   -61   22 12 16   20 41 24   22 49 15   20  3 51

    143  0  0    23  1 44   16 32  2    60   125   -62   23 46  7   22 17  8   24 22 21   21 40 23
    142  0  0    24 32 54   16 32 31    58   126   -62   25 16 23   23 49 12   25 51 53   23 13 13
    141  0  0    26  0 31   16 32 58    57   127   -62   26 43  8   25 17 43   27 17 57   24 42 28
    140  0  0    27 24 44   16 33 25    55   127   -62   28  6 30   26 42 46   28 40 38   26  8 13
    139  0  0    28 45 38   16 33 50    54   128   -62   29 26 36   28  4 29   30  0  5   27 30 37

    138  0  0    30  3 19   16 34 14    52   128   -62   30 43 31   29 22 58   31 16 22   28 49 46
    137  0  0    31 17 56   16 34 36    51   128   -62   31 57 23   30 38 21   32 29 37   30  5 46
    136  0  0    32 29 34   16 34 58    50   128   -62   33  8 17   31 50 43   33 39 56   31 18 44
    135  0  0    33 38 20   16 35 18    48   128   -62   34 16 21   33  0 11   34 47 26   32 28 48
    134  0  0    34 44 20   16 35 38    47   128   -61   35 21 40   34  6 52   35 52 12   33 36  3

    133  0  0    35 47 40   16 35 57    46   128   -61   36 24 22   35 10 52   36 54 22   34 40 35
    132  0  0    36 48 27   16 36 14    44   128   -61   37 24 31   36 12 17   37 54  0   35 42 32
    131  0  0    37 46 47   16 36 31    43   128   -60   38 22 14   37 11 13   38 51 14   36 41 59
    130  0  0    38 42 45   16 36 47    42   127   -60   39 17 37   38  7 47   39 46  8   37 39  2
    129  0  0    39 36 27   16 37  2    41   127   -60   40 10 46   39  2  3   40 38 49   38 33 46

    128  0  0    40 27 59   16 37 16    40   127   -59   41  1 45   39 54  8   41 29 21   39 26 18
    127  0  0    41 17 25   16 37 30    39   126   -59   41 50 39   40 44  6   42 17 51   40 16 42
    126  0  0    42  4 51   16 37 43    38   126   -58   42 37 35   41 32  2   43  4 22   41  5  4
    125  0  0    42 50 22   16 37 55    37   125   -58   43 22 36   42 18  2   43 48 59   41 51 28
    124  0  0    43 34  1   16 38  7    36   125   -57   44  5 48   43  2 10   44 31 48   42 35 59

    123  0  0    44 15 55   16 38 18    35   124   -57   44 47 14   43 44 31   45 12 52   43 18 42
    122  0  0    44 56  6   16 38 29    34   124   -56   45 26 59   44 25  8   45 52 15   43 59 41
    121  0  0    45 34 39   16 38 39    33   123   -56   46  5  7   45  4  6   46 30  2   44 39  0
    120  0  0    46 11 37   16 38 49    32   122   -55   46 41 41   45 41 29   47  6 17   45 16 43
    119  0  0    46 47  5   16 38 58    31   122   -55   47 16 46   46 17 21   47 41  3   45 52 54

    118  0  0    47 21  6   16 39  7    30   121   -55   47 50 24   46 51 44   48 14 23   46 27 36
    117  0  0    47 53 43   16 39 15    30   121   -54   48 22 40   47 24 43   48 46 21   47  0 53
    116  0  0    48 25  0   16 39 23    29   120   -54   48 53 36   47 56 20   49 17  1   47 32 47
    115  0  0    48 54 59   16 39 31    28   119   -53   49 23 15   48 26 39   49 46 24   48  3 23
    114  0  0    49 23 44   16 39 38    27   119   -53   49 51 41   48 55 43   50 14 33   48 32 42

    113  0  0    49 51 16   16 39 45    26   118   -52   50 18 55   49 23 34   50 41 33   49  0 48
    112  0  0    50 17 39   16 39 52    26   117   -52   50 45  1   49 50 15   51  7 24   49 27 44
    111  0  0    50 42 56   16 39 58    25   117   -51   51 10  0   50 15 48   51 32  9   49 53 31
    110  0  0    51  7  7   16 40  4    24   116   -51   51 33 55   50 40 16   51 55 52   50 18 12

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