Update for (29) Amphitrite - January 19, 2000

Jan Manek's update

                     IOTA/IOTA-ES occultation update for
         (29) Amphitrite / TYC 2373 01799 1 event on January 19, 2000
         visible from Russia, Caucasus, Iran, Iraq and Saudi Arabia


Summary 

In the evening January 19, 1999 a faint 10.4 mag star TYC 2373 01799 will be occulted by a large 219 km asteroid (29) Amphitrite. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and ACT star position.

The updated path shows ~0.5 path width east shift with time ~0.6 minutes later compared to Edwin Goffin's nominal prediction.

The path of this occultation runs over Ural area ~16:50-16:58 UT down to SE with Ufa and Sverdlovsk close to path. Later path runs over Caspic sea, Caucasus area ~17:04 UT, western Iran ~17:06 UT, middle Iraq ~17:09 UT and western Saudi Arabia ~17:13 UT.

Event has drop only 0.5 magnitude so probably only non-visual techniques would give a good result. Almost full Moon is close to target.

The event at one glimpse:
 * date and approx. UT time of event: January 19, 2000 @ 17:00 UT
 * magnitude of target star: 10.4
 * magnitude drop [mag]: 0.5 !!!!
 * estimated maximum duration [s]: 70.0
 * path description: given above
 * Goffin's original chart reference: A00_0108(.PS.GZ).

The occultation path:
 * approximate ground width [km]: 220
 * uncertainty [path widths]: 0.5
 * uncertainty in time [s]: 40
 * map: below
 * remarks: Path uncertainities are given according to nominal star
    position errors and expected asteroid positional accuracy.
    !!!!!!!
    Circles along the path are OCCULT exactly calculated centerline points.
    !!!!!!!

Data for the target star:
 * name: TYC 2373 01799 1
 * constellation: Perseus
 * J2000 position [h,m,s; o,',"]: 04h 36m 44.879s; +31o 11' 54.31"
 * position source: ACT
 * estimated accuracy ["]: 0.06" (0.05", 0.04")
 * V mag [mag]: 10.40
 * B-V [mag]: +1.30
 * remarks: TYCHO gives quality flag 6(= non-single?) with 'no investigation
     for duplicity' and dubious astrometric reference 'X' flag. Real star
     position uncertainity may be larger than expected.

     Target star is in very SE Perseus, close to border with Auriga and 
     Taurus. Target star is almost exactly 14.7 degrees north of Aldebaran
     or 4.7 degrees SW of 2.7 mag star iota Aurigae.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 3.0x3.0 degrees
 * limiting magnitude is 11.5
 * labeled stars have indicated SAO numbers





Data for the minor planet:
 * general information:
     number, name: (29) Amphitrite
     approx. diameter [km]: 219
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 52 USNO, 35 TMO
     number of rejected observations: 4 USNO
     time covered by the observations: 1998 06 16 - 2000 01 12
     rms residuals ["] (RA,DE): 0.06", 0.06"
     estimated positional accuracy at epoch of event ["]: 0.06"
     remarks: 

Data for the event:
 * UT date and time of least geocentric approach: 17:07:34 UT
 * approx. V mag of minor planet at event [mag]: 9.7
 * geocentric parallax of minor planet ["]: 5.442
 * magnitude drop [mag]: 0.5
 * estimated maximum duration [s]: 70.0
 * apparent motion of minor planet ["/h]: 9.62
 * angular distance to moon, phase of moon [deg,%]: 28, 97%
 * remarks: 

Calculator(s): Jan Manek






Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   ........ shortened ..........................
   + 69 00 00   + 65 06 15   16 49 09   55   -38
   + 67 00 00   + 63 40 04   16 49 58   57   -38
   + 65 00 00   + 62 05 06   16 50 52   59   -38
   + 63 00 00   + 60 20 32   16 51 52   61   -38
   + 61 00 00   + 58 25 38   16 52 59   63   -38
   + 59 00 00   + 56 19 41   16 54 13   65   -38
   + 57 00 00   + 54 02 09   16 55 35   67   -38
   + 55 00 00   + 51 32 36   16 57 04   69   -38
   + 53 00 00   + 48 50 52   16 58 42   72   -38
   + 51 00 00   + 45 57 00   17 00 29   75   -38
   + 49 00 00   + 42 51 18   17 02 23   77   -37
   + 47 00 00   + 39 34 23   17 04 25   79   -36
   + 45 00 00   + 36 07 01   17 06 34   81   -35
   + 43 00 00   + 32 30 15   17 08 49   81   -34
   + 41 00 00   + 28 45 11   17 11 08   79   -32
   + 39 00 00   + 24 53 06   17 13 31   76   -30
   + 37 00 00   + 20 55 19   17 15 55   73   -28
   + 35 00 00   + 16 53 11   17 18 19   69   -26
   + 33 00 00   + 12 48 07   17 20 41   65   -23
   + 31 00 00   +  8 41 34   17 23 00   61   -21
   + 29 00 00   +  4 35 00   17 25 14   57   -18
   + 27 00 00   +  0 29 55   17 27 21   53   -15
   + 25 00 00   -  3 32 08   17 29 21   49   -12
   + 23 00 00   -  7 29 36   17 31 11   45   -10
   ........ shortened ..........................

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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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