Update for (144) Vibilia - November 12, 2001

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
            (144) Vibilia / TYC 5818-00379-1 on November 12, 2001
            visible from S Portugal, Spain, S France, Switzerland,
                             S Germany and Czechia

Summary 

In the night of November 12, 2001 a 12.0 mag star TYC 5818-00379-1 will be occulted by a 178 km asteroid (144) Vibilia. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and UCAC1 star position.

The updated path shows ~0.7 path width north shift with time ~0.1 minutes later compared to Edwin Goffin's nominal prediction.

Updated path runs over south Portugal shortly after 21:43 UT, Spain from SW to NE with Madrid on central line ~21:43.5 UT, Pic du Midi Observatory, South France ~21:43.8 UT, almost whole Switzerland ~21:44.1 UT, south Germany ~21:44.2 and Czechia ~21:44.3 UT. Parts of path more to NE will have this faint star too low. Please check the path chart for details.

From the accuracy point of view a good event, but the brightness drop is probably on limit for visual observers. CCD scans, video or IOC observations are recommended. Other sources give smaller asteroid diameter around 150km, so the path mat be slightly narrower.

The event at one glimpse:
 * date and approx. UT time of event: November 12, 2001 @ 21:44 UT
 * magnitude of target star: 12.0
 * magnitude drop [mag]: 0.6
 * estimated maximum duration [s]: 13.9
 * path description: given above
 * Goffin's original chart reference: A01_1117

The occultation path:
 * approximate ground width [km]: 200
 * uncertainty [path widths]: 0.6
 * uncertainty in time [s]: 10
 * 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 5818-00379-1
 * constellation: Aquarius
 * J2000 position [h,m,s; o,',"]: 22h 41m 03.665s; -14o 54' 01.27"
 * position source: UCAC1
 * estimated accuracy ["]: 0.02" (0.02", 0.01")
 * V mag [mag]: 11.98
 * B-V [mag]: -0.13
 * remarks:
     Target star is in S Aquarius, about 3.4 degrees W of 3.3 mag star delta
     Aquarii = SAO 165375. Target star is ~25' SE of pair SAO 165221+165227.
     Almost on the same declination, just 6' west of target are two stars.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 3.0x3.0 degrees
 * limiting magnitude is 13.5
 * 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: 79 USNO, 17 TMO
     number of rejected observations: 9 USNO, 6 TMO
     time covered by the observations: 1998 04 21 - 2001 11 01
     rms residuals ["] (RA,DE): 0.09", 0.08"
     estimated positional accuracy at epoch of event ["]: 0.09", 0.08"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 21:36.9 UT
 * approx. V mag of minor planet at event [mag]: 11.6
 * geocentric parallax of minor planet ["]: 5.714
 * magnitude drop [mag]: 0.6
 * estimated maximum duration [s]: 13.9
 * apparent motion of minor planet ["/h]: 41.16
 * angular distance to moon, phase of moon [deg,%]: 137, 7%
 * 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  '  "
   - 30  0  0    20 46 35   21 40 20    54   -33   19 37 24   21 56 34
   - 29  0  0    21 34 35   21 40 30    53   -34   20 25 14   22 44 47
   - 28  0  0    22 22 39   21 40 39    52   -35   21 13  8   23 33  1
   - 27  0  0    23 10 44   21 40 49    51   -36   22  1  3   24 21 14
   - 26  0  0    23 58 46   21 40 58    50   -37   22 48 57   25  9 26
   - 25  0  0    24 46 45   21 41  7    49   -38   23 36 49   25 57 32
   - 24  0  0    25 34 37   21 41 16    48   -39   24 24 35   26 45 30
   - 23  0  0    26 22 21   21 41 24    47   -40   25 12 13   27 33 19
   - 22  0  0    27  9 53   21 41 33    46   -41   25 59 41   28 20 56
   - 21  0  0    27 57 13   21 41 41    44   -42   26 46 57   29  8 19
   - 20  0  0    28 44 17   21 41 49    43   -43   27 33 59   29 55 25
   - 19  0  0    29 31  3   21 41 57    42   -43   28 20 45   30 42 13
   - 18  0  0    30 17 30   21 42  4    41   -44   29  7 12   31 28 40
   - 17  0  0    31  3 36   21 42 12    40   -45   29 53 18   32 14 45
   - 16  0  0    31 49 18   21 42 19    39   -46   30 39  3   33  0 25
   - 15  0  0    32 34 35   21 42 26    38   -47   31 24 23   33 45 39
   - 14  0  0    33 19 25   21 42 32    37   -47   32  9 17   34 30 25
   - 13  0  0    34  3 47   21 42 39    36   -48   32 53 43   35 14 41
   - 12  0  0    34 47 38   21 42 45    35   -49   33 37 40   35 58 26
   - 11  0  0    35 30 58   21 42 51    34   -49   34 21  7   36 41 39
   - 10  0  0    36 13 44   21 42 57    33   -50   35  4  1   37 24 18
   -  9  0  0    36 55 57   21 43  2    32   -51   35 46 22   38  6 21
   -  8  0  0    37 37 34   21 43  8    31   -51   36 28  9   38 47 48
   -  7  0  0    38 18 35   21 43 13    30   -52   37  9 20   39 28 38
   -  6  0  0    38 58 58   21 43 18    29   -52   37 49 54   40  8 50
   -  5  0  0    39 38 43   21 43 22    28   -53   38 29 51   40 48 23
   -  4  0  0    40 17 49   21 43 27    27   -53   39  9 10   41 27 16
   -  3  0  0    40 56 15   21 43 31    26   -53   39 47 49   42  5 29
   -  2  0  0    41 34  1   21 43 35    25   -54   40 25 49   42 43  1
   -  1  0  0    42 11  7   21 43 39    24   -54   41  3  9   43 19 51
      0  0  0    42 47 31   21 43 43    23   -54   41 39 49   43 56  0
      1  0  0    43 23 14   21 43 46    22   -55   42 15 47   44 31 27
      2  0  0    43 58 15   21 43 49    21   -55   42 51  4   45  6 11
      3  0  0    44 32 34   21 43 52    20   -55   43 25 40   45 40 14
      4  0  0    45  6 12   21 43 55    19   -55   43 59 34   46 13 34
      5  0  0    45 39  7   21 43 58    18   -55   44 32 47   46 46 11
      6  0  0    46 11 20   21 44  1    17   -55   45  5 17   47 18  6
      7  0  0    46 42 52   21 44  3    17   -55   45 37  7   47 49 20
      8  0  0    47 13 41   21 44  5    16   -56   46  8 15   48 19 51
      9  0  0    47 43 50   21 44  8    15   -56   46 38 41   48 49 40
     10  0  0    48 13 17   21 44 10    14   -56   47  8 27   49 18 48
     11  0  0    48 42  3   21 44 11    13   -56   47 37 31   49 47 15
     12  0  0    49 10  8   21 44 13    12   -56   48  5 55   50 15  1
     13  0  0    49 37 33   21 44 15    12   -55   48 33 39   50 42  7
     14  0  0    50  4 18   21 44 16    11   -55   49  0 43   51  8 33
     15  0  0    50 30 24   21 44 17    10   -55   49 27  7   51 34 19
     16  0  0    50 55 50   21 44 19     9   -55   49 52 53   51 59 26
     17  0  0    51 20 38   21 44 20     9   -55   50 17 59   52 23 55
     18  0  0    51 44 48   21 44 21     8   -55   50 42 28   52 47 45
     19  0  0    52  8 20   21 44 22     7   -55   51  6 19   53 10 58
     20  0  0    52 31 15   21 44 23     6   -55   51 29 32   53 33 34
     21  0  0    52 53 34   21 44 23     6   -54   51 52  9   53 55 34
     22  0  0    53 15 16   21 44 24     5   -54   52 14 10   54 16 57
     23  0  0    53 36 23   21 44 24     4   -54   52 35 35   54 37 46
   ........................... 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-|
--------------------------------------------------------------------U---U---