Update for (155) Scylla - March 22, 2000

Jan Manek's update

                  IOTA/IOTA-ES occultation update for
        (155) Scylla / TYC 2465-01335-1 event on March 22, 2000
           visible from S Norway, S Sweden, Poland, E Slovakia,
       E Hungary, Romania, E Bulgaria, W Turkey and near East area


Summary 

In the night of March 22, 2000 a ~9.4 mag star TYC 2465-01335-1 will be occulted by a 50 km asteroid (155) Scylla. This update is based on USNO/Flagstaff astrometry for the asteroid and Tycho-2 star position.

The updated path shows significant ~0.9" western shift with time ~1.8 minutes earlier compared to Edwin Goffin's nominal prediction.

The path of this occultation runs over SW Norway, just south of Oslo at ~20:55 UT, SW Sweden just east of Goteborg 20:55.5 UT, middle Poland from NW to SE around ~20:56 UT with Lodz, Krakow and Sanok near/in the path, eastern Slovakia ~20:56.7 UT, eastern Hungary ~20:56.8 UT, Romania ~20:57 UT with Bucharest just east of path, eastern Bulgaria ~20:57.6 UT with Burgas just east of path and western Turkey ~20:58 UT. Near East area is crossed at ~20:59.5 UT with N Israel, Palestina and Jordan (with Amman on east limit), and western Saudi Arabia in path.

Keep in mind the 2.7 path width uncertainity and have enough time to locate the correct star. As the expected duration is only 3.7 seconds, video records are recommended to have good time resolution.

Please inform other observers within your area and expected path errors to have a reasonable coverage for this small body. Good luck !!!

The event at one glimpse:
 * date and approx. UT time of event: March 22, 2000 @ 20:56 UT
 * magnitude of target star: 9.4 
 * magnitude drop [mag]: 5.9
 * estimated maximum duration [s]: 3.7 
 * path description: given above
 * Goffin's original chart reference: A00_0316

The occultation path:
 * approximate ground width [km]: 60 
 * uncertainty [path widths]: 2.7
 * uncertainty in time [s]: 15
 * map: below
 * remarks: Path uncertainities are given according to nominal star
    position errors and expected asteroid positional accuracy.
    !!!!!!!
    Thick line indicates the centerline for this event.
    !!!!!!!

Data for the target star:
 * name: TYC 2465-01335-1
 * constellation: Lynx  
 * J2000 position [h,m,s; o,',"]: 07h 31m 40.513s; +36o 44' 59.03"
 * position source: Tycho-2  
 * estimated accuracy ["]: 0.04 (0.03", 0.03")
 * V mag [mag]: 9.41
 * B-V [mag]: +0.99
 * remarks: 
     Target star is in very SW Lynx, about 4.9 degrees north of 2.0 mag star
     alpha Geminorum = Castor (upper one of the two bright). There is 6.4 mag
     star SAO 60173 ~34' NE of target, 8.6 mag star SAO 60135 about 15' west
     of target or 8.2 mag star SAO 60153 about 14' SSE of target star. 
     Be sure to have enough time for locating the correct star.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 2.5x2.5 degrees
 * limiting magnitude is 12.5
 * labeled stars have indicated SAO numbers





Data for the minor planet:
 * general information:
     number, name: (155) Scylla   
     approx. diameter [km]: 50
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone)
     number of used observations: 42 USNO
     number of rejected observations: 9 USNO
     time covered by the observations: 1998 07 02 - 2000 03 12
     rms residuals ["] (RA,DE): 0.12", 0.14"
     estimated positional accuracy at epoch of event ["]: 0.08"
     remarks: Overall rms is given above, with old positions showing large
       scatter; recent positions are more compact so I estimated accuracy 
       to be better - about 0.08"

Data for the event:
 * UT date and time of least geocentric approach: 20:55.0  UT
 * approx. V mag of minor planet at event [mag]: 15.3
 * geocentric parallax of minor planet ["]: 5.272
 * magnitude drop [mag]: 5.9
 * estimated maximum duration [s]: 3.7 
 * apparent motion of minor planet ["/h]: 40.34
 * angular distance to moon, phase of moon [deg,%]: 103, 93%
 * remarks: 

Calculator(s): Jan Manek








Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
      o  '  "     o  '  "    h  m  s     o     o
   ........ shortened ..........................
      3  0  0    64 28  9   20 54 12    59   -17
      4  0  0    63 51 51   20 54 18    59   -18
      5  0  0    63 14  4   20 54 24    59   -18
      6  0  0    62 34 45   20 54 31    59   -19
      7  0  0    61 53 52   20 54 38    59   -20
      8  0  0    61 11 20   20 54 45    59   -21
      9  0  0    60 27  9   20 54 52    59   -22
     10  0  0    59 41 16   20 54 60    59   -23
     11  0  0    58 53 39   20 55  8    59   -24
     12  0  0    58  4 15   20 55 16    59   -25
     13  0  0    57 13  5   20 55 24    59   -26
     14  0  0    56 20  6   20 55 33    59   -27
     15  0  0    55 25 18   20 55 42    59   -28
     16  0  0    54 28 42   20 55 51    59   -29
     17  0  0    53 30 17   20 55 60    58   -30
     18  0  0    52 30  6   20 56 10    58   -31
     19  0  0    51 28  8   20 56 19    58   -32
     20  0  0    50 24 28   20 56 29    57   -34
     21  0  0    49 19  7   20 56 40    57   -35
     22  0  0    48 12 10   20 56 50    56   -36
     23  0  0    47  3 41   20 57  1    55   -37
     24  0  0    45 53 45   20 57 11    55   -39
     25  0  0    44 42 27   20 57 22    54   -40
     26  0  0    43 29 54   20 57 33    53   -42
     27  0  0    42 16 13   20 57 44    52   -43
     28  0  0    41  1 29   20 57 55    51   -45
     29  0  0    39 45 52   20 58  6    50   -46
     30  0  0    38 29 29   20 58 17    49   -48
     31  0  0    37 12 27   20 58 28    48   -49
     32  0  0    35 54 56   20 58 39    47   -51
     33  0  0    34 37  2   20 58 49    45   -52
     34  0  0    33 18 55   20 58 60    44   -54
     35  0  0    32  0 43   20 59 10    43   -55
     36  0  0    30 42 33   20 59 20    42   -57
     37  0  0    29 24 34   20 59 30    40   -58
     38  0  0    28  6 52   20 59 40    39   -60
     39  0  0    26 49 34   20 59 49    37   -61
     40  0  0    25 32 48   20 59 58    36   -63
     41  0  0    24 16 39   21  0  7    35   -64
     42  0  0    23  1 14   21  0 15    33   -66
     43  0  0    21 46 37   21  0 23    32   -67
     44  0  0    20 32 54   21  0 31    30   -68
     45  0  0    19 20  9   21  0 38    29   -70
     46  0  0    18  8 26   21  0 45    27   -71
     47  0  0    16 57 48   21  0 52    26   -72
     48  0  0    15 48 20   21  0 58    24   -73
     49  0  0    14 40  3   21  1  3    23   -74
     50  0  0    13 32 59   21  1  9    22   -75
     51  0  0    12 27 12   21  1 14    20   -76
     52  0  0    11 22 43   21  1 18    19   -76
     53  0  0    10 19 33   21  1 23    17   -77
     54  0  0     9 17 43   21  1 27    16   -77
     55  0  0     8 17 13   21  1 30    14   -77
     56  0  0     7 18  6   21  1 33    13   -77
     57  0  0     6 20 20   21  1 36    12   -77
     58  0  0     5 23 57   21  1 39    10   -77
     59  0  0     4 28 56   21  1 41     9   -76
     60  0  0     3 35 16   21  1 43     8   -76
     61  0  0     2 42 59   21  1 44     6   -75
   ........ shortened ..........................

----------------------------------------------------------------------------
Jan Manek
Stefanik Observatory                Private :
Petrin 205                          Werichova 950
118 46  Praha 1                     152 00  Praha 5 - Barrandov     |_|_|
Czech Republic                      Czech Republic                  /   \
Internet : jmanek@mbox.vol.cz                                      |-O-O-|
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