Update for (250) Bettina - January 5/6, 1999

Update computed by Jan Manek; issued 04 Jan 1999 14:17:51 +0100 (CET)

Update computed by Pedro Valdes Sada; issued 03 Jan 1999 17:51:13 -0600

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
            (250) Bettina / TYC 2967 01618 event on 1999, January 5/6
            visible from Saudi Arabia, Mediterrian and Florida (USA)

Summary

On the night January 5/6, 1999 will be occulted 9.4 mag star by a 86km asteroid (250) Bettina. This update is based on USNO/Flagstaff and TMO astrometry for asteroid and ACT star position. The updated path is shifted significantly south being also about 0.5 minute earlier that Goffin's nominal prediction (see 1999 predictions for finder chart and nominal prediction). Compared to earlier update of Pedro Sada this update is about 1 path width north with small time correction. Current uncertainity is still about 1.5 path widths. For Europe this event takes place near zenith.


The event at one glimpse:
 * date and approx. UT time of event: January, 6, 1999 @ 00:35 UT (Euro),
                                                         00:44 UT (USA)
 * magnitude of target star: 9.4
 * magnitude drop [mag]: 2.3
 * estimated maximum duration [s]: 7.6
 * path description: Path runs over Saudi Arabia, Jordania with Amman just
     north of path ~00:31:30 UT and Israel in path few seconds later. Around
     ~00:33 path runs over souther Greece, ~00:34 UT hits southern Italy with
     Rome just north of path, ~00:35 UT Corse island and around ~00:36 runs
     over southern France just north of France/Spain border. After crossing
     the Atlantic Ocean the shadow hits ~00:44 also northen part of Florida
     (USA).

The occultation path:
 * approximate width [km]: 90
 * uncertainty [path widths]: 1.5
 * uncertainty in time [s]: 15
 * map: attached two - one for Europe and one for North America.
 * remarks: Path uncertainities are given according to nominal star position
    errors and expected asteroid positional accuracy. For any larger shift is
    responsible true star position.
    !!!!!!!
    Circles along the path are OCCULT exactly calculated centerline points.
    !!!!!!!

Data for the target star:
 * name: TYC 2967 01618
 * constellation: Lynx
 * J2000 position [h,m,s; o,',"]: 07h 43m 14.343s; +41o 15' 56.91"
 * position source: ACT
 * estimated accuracy ["]: 0.04"  (0.03, 0.02)
 * V mag [mag]: 9.44
 * remarks: Target star is 13.25 degrees almost exactly north of 1.2 mag
    star beta Gem (Pollux). The magnitude given is Johnson V mag. Be sure to
    have enough time for locating the correct star in the Lynx constellation.

Data for the minor planet:
 * general information:
     mumber, name: (250) Bettina
     approx. diameter [km]: 86
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 11 USNO, 2 TMO
     number of rejected observations: 1 USNO (Nov 8, 1997),
     time covered by the observations: 1998 09 30 - 1998 12 27
     rms residuals ["] (RA,DE): 0.06", 0.06"
     estimated positional accuracy at epoch of event ["]: 0.08"
     remarks: The 1997 USNO position wasn't included in the solution as it
       wasn't possible the check accuracy of this single point.

Data for the event:
 * UT date and time of least geocentric approach: 00:35:42 UT
 * approx. V mag of minor planet at event [mag]: 11.6
 * geocentric parallax of minor planet ["]: 4.832
 * magnitude drop [mag]: 2.3
 * estimated maximum duration [s]: 7.6
 * apparent motion of minor planet ["/h]: 30.68
 * angular distance to moon, phase of moon [deg,%]: 47, 83%
 * remarks:

Calculator(s): Manek











Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   + 73 00 00   +  0 18 59    0 26 39   16   -11
   + 71 00 00   +  2 12 45    0 26 47   19   -13
   + 69 00 00   +  4 06 10    0 26 56   21   -16
   + 67 00 00   +  5 58 52    0 27 06   24   -19
   + 65 00 00   +  7 50 31    0 27 17   27   -21
   + 63 00 00   +  9 40 46    0 27 30   29   -23
   + 61 00 00   + 11 29 19    0 27 43   32   -26
   + 59 00 00   + 13 15 54    0 27 57   35   -28
   + 57 00 00   + 15 00 14    0 28 12   37   -31
   + 55 00 00   + 16 42 07    0 28 27   40   -33
   + 53 00 00   + 18 21 21    0 28 43   42   -35
   + 51 00 00   + 19 57 47    0 29 00   44   -37
   + 49 00 00   + 21 31 15    0 29 17   47   -39
   + 47 00 00   + 23 01 40    0 29 34   49   -41
   + 45 00 00   + 24 28 56    0 29 51   51   -43
   + 43 00 00   + 25 53 01    0 30 09   54   -45
   + 41 00 00   + 27 13 52    0 30 27   56   -47
   + 39 00 00   + 28 31 29    0 30 44   58   -49
   + 37 00 00   + 29 45 50    0 31 02   60   -51
   + 35 00 00   + 30 56 58    0 31 20   62   -52
   + 33 00 00   + 32 04 53    0 31 37   64   -54
   + 31 00 00   + 33 09 39    0 31 55   66   -55
   + 29 00 00   + 34 11 18    0 32 12   68   -57
   + 27 00 00   + 35 09 53    0 32 29   70   -58
   + 25 00 00   + 36 05 29    0 32 46   71   -59
   + 23 00 00   + 36 58 08    0 33 03   73   -60
   + 21 00 00   + 37 47 55    0 33 20   75   -62
   + 19 00 00   + 38 34 55    0 33 36   77   -63
   + 17 00 00   + 39 19 10    0 33 52   78   -64
   + 15 00 00   + 40 00 46    0 34 08   80   -64
   + 13 00 00   + 40 39 46    0 34 24   81   -65
   + 11 00 00   + 41 16 15    0 34 40   83   -66
   +  9 00 00   + 41 50 15    0 34 55   84   -66
   +  7 00 00   + 42 21 52    0 35 10   85   -67
   +  5 00 00   + 42 51 08    0 35 25   86   -67
   +  3 00 00   + 43 18 07    0 35 40   86   -67
   +  1 00 00   + 43 42 51    0 35 54   86   -68
   -  1 00 00   + 44 05 24    0 36 09   85   -68
   -  3 00 00   + 44 25 49    0 36 23   84   -68
   -  5 00 00   + 44 44 08    0 36 37   83   -68
   -  7 00 00   + 45 00 22    0 36 51   82   -68
   -  9 00 00   + 45 14 35    0 37 04   81   -67
   - 11 00 00   + 45 26 48    0 37 18   80   -67
   - 13 00 00   + 45 37 02    0 37 31   78   -67
   - 15 00 00   + 45 45 18    0 37 44   77   -66
   - 17 00 00   + 45 51 38    0 37 58   76   -66
   ........... ocean part cutted out ...........
   - 67 00 00   + 37 22 26    0 43 01   39   -39
   - 69 00 00   + 36 30 31    0 43 12   37   -37
   - 71 00 00   + 35 35 34    0 43 23   36   -35
   - 73 00 00   + 34 37 31    0 43 33   34   -34
   - 75 00 00   + 33 36 18    0 43 44   32   -32
   - 77 00 00   + 32 31 49    0 43 54   30   -30
   - 79 00 00   + 31 24 01    0 44 03   28   -28
   - 81 00 00   + 30 12 51    0 44 13   26   -27
   - 83 00 00   + 28 58 16    0 44 21   24   -25
   - 85 00 00   + 27 40 12    0 44 30   22   -23
   - 87 00 00   + 26 18 41    0 44 37   19   -21
   - 89 00 00   + 24 53 40    0 44 45   17   -19
   - 91 00 00   + 23 25 12    0 44 51   15   -16
   - 93 00 00   + 21 53 18    0 44 56   12   -14
   - 95 00 00   + 20 18 04    0 45 01   10   -12
   - 97 00 00   + 18 39 34    0 45 05    8   -10
   - 99 00 00   + 16 57 58    0 45 08    5    -7
   -101 00 00   + 15 13 24    0 45 09    2    -5

----------------------------------------------------------------------------
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-|
--------------------------------------------------------------------U---U---

Pedro Valdes Sada's update
                     IOTA/IOTA-ES occultation update for
            (250) Bettina / TYC 2967 01618 event on 1999 January 6
           visible from Sudi Arabia, the Mediterranean and the U.S.A.


Summary 
On January 6, 1999 (UT) a 9.6 mag star will be occulted by the ~85 km
asteroid (250) Bettina. This update is based on recent astrometry from
the USNO for the asteroid and the ACT star position. The path is shifted
to the southeast by about 7 path widths compared with Goffin's ACT
modified nominal prediction, and about 40 seconds earlier.

The event at one glimpse:
 * date and approx. UT time of event: January, 6, 1999 @ 0:36 UT
 * magnitude of target star: 9.6 (ACT value)
 * magnitude drop [mag]: 2.2
 * estimated maximum duration [s]: 7.6
 * path description: The shadow finishes crossing the Arabian Peninsula
(near Cairo) and enters Mediterranean waters at ~0:31.5 UT. Goes over
Crete one minute later, between the boot of Italy and Sicily at ~0:34,
the Island of Sardinia a minute later, and over the border between
France
and Spain ~0:36, finally skirting the northern coast of Spain. After
crossing the Atlantic it briefly touches the USA (Florida) at ~0:44 UT.

The occultation path:
 * approximate width [km]: ~90
 * uncertainty [path widths]: ~2
 * map: attached
 * remarks: The path shifts northwest by about 2 pathwidths if the
first USNO observation (11/97) is removed from the solution. The time
remains nearly unchanged.

Data for the target star:
 * name: TYC 2967 01618
 * constellation: Lynx
 * J2000 position [h,m,s; o,',"]: 07h 43m 14.343s; +41* 15' 56.91"
 * position source: ACT
 * estimated accuracy ["]: medium (quality flag 4)
 * V mag [mag]: 9.6
 * remarks: none.

Data for the minor planet:
 * general information:
     mumber, name: (250) Bettina
     approx. diameter [km]: 85
 * orbital information
     orbit source: calculation by Sada (using CAA)
     source of used astrometry: USNO/Flagstaff (R. Stone)
     number of used observations: 11 USNO
     number of rejected observations: none (see remarks).
     time covered by the observations: 1997 10 08 - 1998 12 27
     rms residuals ["] (RA,DE): 0.03" (combined)
     estimated positional accuracy at epoch of event ["]: 0.2"
     remarks: The path shifts northwest by about 2 pathwidths if the
        first USNO observation (11/97) is removed from the solution.
        The time remains nearly unchanged.

Data for the event:
 * UT date and time of least geocentric approach: 0:35:36 UT
 * uncertainty in time [s]: ~20
 * approx. V mag of minor planet at event [mag]: 11.6
 * geocentric parallax of minor planet ["]: 4.832
 * magnitude drop [mag]: 2.2
 * estimated maximum duration [s]: 7.6
 * apparent motion of minor planet ["/h]: 30.69
 * angular distance to moon, phase of moon [deg,%]: 47, 83%
 * remarks:

Calculator(s): Sada











Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   -101 00 00   + 13 43 59    0 45 00    1    -4
   - 99 00 00   + 15 29 20    0 44 59    4    -7
   - 97 00 00   + 17 11 47    0 44 57    7    -9
   - 95 00 00   + 18 51 09    0 44 53    9   -11
   - 93 00 00   + 20 27 19    0 44 49   11   -14
   - 91 00 00   + 22 00 10    0 44 44   14   -16
   - 89 00 00   + 23 29 36    0 44 38   16   -18
   - 87 00 00   + 24 55 36    0 44 31   19   -20
   - 85 00 00   + 26 18 07    0 44 23   21   -22
   - 83 00 00   + 27 37 09    0 44 15   23   -24
   - 81 00 00   + 28 52 43    0 44 07   25   -26
   - 79 00 00   + 30 04 51    0 43 58   27   -28
   - 77 00 00   + 31 13 36    0 43 48   29   -30
   - 75 00 00   + 32 19 01    0 43 38   31   -32
   - 73 00 00   + 33 21 09    0 43 28   33   -34
   - 71 00 00   + 34 20 05    0 43 17   35   -35
   - 69 00 00   + 35 15 53    0 43 06   37   -37
   - 67 00 00   + 36 08 38    0 42 55   39   -39
   - 65 00 00   + 36 58 24    0 42 44   40   -40
   - 63 00 00   + 37 45 16    0 42 33   42   -42
   - 61 00 00   + 38 29 20    0 42 21   44   -43
   - 59 00 00   + 39 10 39    0 42 10   46   -45
   - 57 00 00   + 39 49 18    0 41 58   47   -46
   - 55 00 00   + 40 25 21    0 41 46   49   -47
   - 53 00 00   + 40 58 53    0 41 34   50   -49
   - 51 00 00   + 41 29 57    0 41 22   52   -50
   - 49 00 00   + 41 58 38    0 41 10   53   -51
   - 47 00 00   + 42 24 58    0 40 58   55   -53
   - 45 00 00   + 42 49 02    0 40 46   56   -54
   - 43 00 00   + 43 10 52    0 40 33   58   -55
   - 41 00 00   + 43 30 31    0 40 21   59   -56
   - 39 00 00   + 43 48 01    0 40 09   61   -57
   - 37 00 00   + 44 03 26    0 39 56   62   -58
   - 35 00 00   + 44 16 46    0 39 44   64   -59
   - 33 00 00   + 44 28 04    0 39 31   65   -60
   - 31 00 00   + 44 37 21    0 39 18   66   -61
   - 29 00 00   + 44 44 39    0 39 06   68   -62
   - 27 00 00   + 44 49 58    0 38 53   69   -63
   - 25 00 00   + 44 53 20    0 38 40   70   -64
   - 23 00 00   + 44 54 44    0 38 27   72   -65
   - 21 00 00   + 44 54 12    0 38 14   73   -65
   - 19 00 00   + 44 51 42    0 38 01   75   -66
   - 17 00 00   + 44 47 16    0 37 48   76   -67
   - 15 00 00   + 44 40 51    0 37 34   77   -67
   - 13 00 00   + 44 32 28    0 37 21   79   -68
   - 11 00 00   + 44 22 06    0 37 07   80   -68
   -  9 00 00   + 44 09 43    0 36 53   81   -68
   -  7 00 00   + 43 55 18    0 36 39   83   -69
   -  5 00 00   + 43 38 49    0 36 25   84   -69
   -  3 00 00   + 43 20 14    0 36 11   85   -69
   -  1 00 00   + 42 59 31    0 35 57   86   -69
   +  1 00 00   + 42 36 37    0 35 42   87   -69
   +  3 00 00   + 42 11 31    0 35 27   87   -68
   +  5 00 00   + 41 44 08    0 35 12   86   -68
   +  7 00 00   + 41 14 26    0 34 57   85   -68
   +  9 00 00   + 40 42 22    0 34 42   84   -67
   + 11 00 00   + 40 07 51    0 34 26   82   -67
   + 13 00 00   + 39 30 51    0 34 11   81   -66
   + 15 00 00   + 38 51 18    0 33 55   79   -65
   + 17 00 00   + 38 09 07    0 33 38   78   -64
   + 19 00 00   + 37 24 15    0 33 22   76   -63
   + 21 00 00   + 36 36 38    0 33 05   75   -62
   + 23 00 00   + 35 46 11    0 32 48   73   -61
   + 25 00 00   + 34 52 51    0 32 31   71   -60
   + 27 00 00   + 33 56 34    0 32 14   69   -58
   + 29 00 00   + 32 57 15    0 31 57   67   -57
   + 31 00 00   + 31 54 52    0 31 39   65   -55
   + 33 00 00   + 30 49 21    0 31 22   63   -54
   + 35 00 00   + 29 40 40    0 31 04   61   -52
   + 37 00 00   + 28 28 46    0 30 46   59   -51
   + 39 00 00   + 27 13 39    0 30 28   57   -49
   + 41 00 00   + 25 55 16    0 30 11   55   -47
   + 43 00 00   + 24 33 39    0 29 53   53   -45
   + 45 00 00   + 23 08 49    0 29 35   51   -43
   + 47 00 00   + 21 40 48    0 29 18   48   -41
   + 49 00 00   + 20 09 39    0 29 01   46   -39
   + 51 00 00   + 18 35 29    0 28 44   44   -37
   + 53 00 00   + 16 58 24    0 28 28   41   -35
   + 55 00 00   + 15 18 33    0 28 12   39   -32
   + 57 00 00   + 13 36 05    0 27 57   36   -30
   + 59 00 00   + 11 51 12    0 27 42   34   -28
   + 61 00 00   + 10 04 09    0 27 28   31   -25
   + 63 00 00   +  8 15 11    0 27 15   28   -23
   + 65 00 00   +  6 24 35    0 27 03   26   -21
   + 67 00 00   +  4 32 40    0 26 52   23   -18
   + 69 00 00   +  2 39 46    0 26 43   20   -16
   + 71 00 00   +  0 46 14    0 26 34   18   -13
   + 73 00 00   -  1 07 33    0 26 26   15   -10
   + 75 00 00   -  3 01 14    0 26 20   12    -8
   + 77 00 00   -  4 54 26    0 26 15    9    -5
   + 79 00 00   -  6 46 46    0 26 11    7    -3
   + 81 00 00   -  8 37 52    0 26 09    4    -0



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