Update for (144) Vibilia - December 30, 2001

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
            (144) Vibilia / TYC 5258-00552-1 on December 30, 2001
            visible from England, N Denmark, S Sweden and Finland

Summary 

In the evening of December 30, 2001 a 11.0 mag star TYC 5258-00552-1 will be occulted by a 178 km asteroid (144) Vibilia. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and combined UCAC and Tycho-2 star position.

The updated path shows ~0.5 path width north shift with no time shift compared to Edwin Goffin's nominal prediction.

Updated path runs over England ~17:59.3 UT, north Denmark ~17:59.7 UT, S Sweden with Uppsala ~17:59.9 UT and Finland ~18:00 UT. Please check the path chart for details.

From the accuracy point of view a good event, brightness drop of 1.5 mags is well within possibilities of visual observers. CCD scans, video or IOC observations are however recommended. Other sources give smaller asteroid diameter around 150km, so the path may be slightly narrower.

Clear sky and good luck !!!

The event at one glimpse:
 * date and approx. UT time of event: December 30, 2001 @ 18:59 UT
 * magnitude of target star: 11.0
 * magnitude drop [mag]: 1.5
 * estimated maximum duration [s]: 6.2
 * path description: given above
 * Goffin's original chart reference: A01_1213

The occultation path:
 * approximate ground width [km]: 240
 * uncertainty [path widths]: 0.5
 * uncertainty in time [s]: 5
 * map: below
 * remarks: Path uncertainities are given according to nominal star
    position errors and expected asteroid positional accuracy.

Data for the target star:
 * name: TYC 5258-00552-1
 * constellation: Aquarius
 * J2000 position [h,m,s; o,',"]: 23h 45m 27.6371s; -05o 49' 08.225"
 * position source: weighted mean from UCAC and Tycho-2
 * estimated accuracy ["]: 0.01" (0.005", 0.005")
 * V mag [mag]: 11.00
 * B-V [mag]: +0.56
 * remarks:
     Recent UCAC position was provided by Marion and Norbert Zacharias.
     Target star is in NE Aquarius, about 7.8 degrees east of 4.2 mag star phi
     Aquarii = SAO 146585 which is just 1.2 degrees east of Mars. Target star
     is 57' NW of 6.1 mag star SAO 146919 and 9.4' SE of target is 9.4 mag
     SAO 146890.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 3.0x3.0 degrees
 * limiting magnitude is 13.0
 * labeled stars have indicated SAO numbers





Data for the minor planet:
 * general information:
     number, name: (144) Vibilia
     approx. diameter [km]: 178
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 99 USNO, 19 TMO
     number of rejected observations: 14 USNO, 8 TMO
     time covered by the observations: 1998 12 13 - 2001 12 19
     rms residuals ["] (RA,DE): 0.07", 0.06"
     estimated positional accuracy at epoch of event ["]: 0.06", 0.06"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 17:57.5 UT
 * approx. V mag of minor planet at event [mag]: 12.2
 * geocentric parallax of minor planet ["]: 4.265
 * magnitude drop [mag]: 1.5
 * estimated maximum duration [s]: 6.2
 * apparent motion of minor planet ["/h]: 69.01
 * angular distance to moon, phase of moon [deg,%]: 109, 100%
 * remarks:

Calculator(s): Jan Manek





Path coordinates:
                                                   Latitude   Latitude
                  Centre               Altitude       Path Limits
  E. Longitude   Latitude      U.T.   star   sun   Limit 1    Limit 2
   ........................... shortened .............................
      o  '  "     o  '  "    h  m  s     o     o    o  '  "    o  '  "
   - 10  0  0    46 35 37   17 58 59    38    -9   45  9 52   48  4  3
   -  9  0  0    47 11 30   17 59  2    37   -10   45 45 39   48 40  5
   -  8  0  0    47 47  8   17 59  5    36   -11   46 21  9   49 15 49
   -  7  0  0    48 22 27   17 59  8    36   -12   46 56 23   49 51 14
   -  6  0  0    48 57 27   17 59 10    35   -13   47 31 19   50 26 18
   -  5  0  0    49 32  6   17 59 13    34   -14   48  5 55   51  1  1
   -  4  0  0    50  6 24   17 59 15    34   -14   48 40 11   51 35 21
   -  3  0  0    50 40 19   17 59 18    33   -15   49 14  6   52  9 17
   -  2  0  0    51 13 51   17 59 20    32   -16   49 47 38   52 42 48
   -  1  0  0    51 46 57   17 59 23    32   -17   50 20 46   53 15 52
      0  0  0    52 19 38   17 59 25    31   -18   50 53 30   53 48 30
      1  0  0    52 51 52   17 59 27    30   -18   51 25 48   54 20 40
      2  0  0    53 23 39   17 59 29    30   -19   51 57 40   54 52 21
      3  0  0    53 54 58   17 59 31    29   -20   52 29  6   55 23 33
      4  0  0    54 25 48   17 59 33    28   -20   53  0  3   55 54 14
      5  0  0    54 56  8   17 59 35    28   -21   53 30 32   56 24 26
      6  0  0    55 25 58   17 59 37    27   -22   54  0 32   56 54  6
      7  0  0    55 55 18   17 59 39    26   -22   54 30  3   57 23 14
      8  0  0    56 24  8   17 59 41    26   -23   54 59  4   57 51 50
      9  0  0    56 52 26   17 59 42    25   -24   55 27 34   58 19 55
     10  0  0    57 20 12   17 59 44    24   -24   55 55 35   58 47 26
     11  0  0    57 47 27   17 59 45    24   -25   56 23  4   59 14 25
     12  0  0    58 14 10   17 59 47    23   -25   56 50  2   59 40 52
     13  0  0    58 40 21   17 59 48    22   -26   57 16 29   60  6 45
     14  0  0    59  5 60   17 59 50    22   -26   57 42 25   60 32  6
     15  0  0    59 31  7   17 59 51    21   -27   58  7 49   60 56 53
     16  0  0    59 55 42   17 59 52    21   -27   58 32 42   61 21  8
     17  0  0    60 19 44   17 59 53    20   -28   58 57  4   61 44 50
     18  0  0    60 43 15   17 59 54    19   -28   59 20 55   62  8  0
     19  0  0    61  6 15   17 59 56    19   -29   59 44 14   62 30 38
     20  0  0    61 28 42   17 59 57    18   -29   60  7  2   62 52 43
     21  0  0    61 50 39   17 59 58    18   -30   60 29 20   63 14 17
     22  0  0    62 12  4   17 59 58    17   -30   60 51  7   63 35 19
     23  0  0    62 32 59   17 59 59    16   -31   61 12 23   63 55 51
     24  0  0    62 53 24   18  0  0    16   -31   61 33  9   64 15 51
     25  0  0    63 13 18   18  0  1    15   -31   61 53 26   64 35 22
     26  0  0    63 32 42   18  0  2    15   -32   62 13 13   64 54 22
     27  0  0    63 51 38   18  0  3    14   -32   62 32 31   65 12 53
     28  0  0    64 10  4   18  0  3    14   -32   62 51 20   65 30 54
     29  0  0    64 28  1   18  0  4    13   -33   63  9 40   65 48 27
     30  0  0    64 45 31   18  0  4    13   -33   63 27 32   66  5 32
     31  0  0    65  2 33   18  0  5    12   -33   63 44 57   66 22  9
     32  0  0    65 19  7   18  0  6    12   -34   64  1 54   66 38 19
     33  0  0    65 35 15   18  0  6    11   -34   64 18 25   66 54  2
     34  0  0    65 50 56   18  0  7    11   -34   64 34 29   67  9 18
     35  0  0    66  6 11   18  0  7    10   -35   64 50  7   67 24  9
     36  0  0    66 21  0   18  0  8    10   -35   65  5 19   67 38 34
   ........................... shortened .............................

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