Update for (192) Nausikaa - September 19/20, 2000

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
       (192) Nausikaa / TYC 1213-00825-1 on September 19/20, 2000
          visible from Sardegna, France, SE England and Ireland 


Summary 

In the night of September 19/20, 2000 a 9.2 mag star TYC 1213-00825-1 = SAO 92760 will be occulted by a 107 km asteroid (192) Nausikaa. This update is based on USNO/Flagstaff, TMO and Geneva astrometry for the asteroid and Tycho-2 star position.

The updated path shows no significant path shift with time ~0.1 minutes earlier compared to Edwin Goffin's nominal prediction.

The path of this occultation runs over Africa and Mediterrian Sea and grazes west Sicily ~0:47 UT. Sardegna and S Corse is in path ~0:49 UT and then path runs to NW over central France at ~0:51-0:54 UT with Marseille on W limit ~0:51 UT. SE England is in path ~0:55 UT and Ireland at ~0:56 UT.

Please follow central line circles in this case - it is more reliable than path limits. Note also the brightness drop is under 1 magnitude, use the nearby star SAO 92757 (9' NW of target) as a brightness reference for this up to 29 seconds long event.

The event at one glimpse:
 * date and approx. UT time of event: September 10, 2000 @ 00:52 UT (Europe)
 * magnitude of target star: 9.2
 * magnitude drop [mag]: 0.9
 * estimated maximum duration [s]: 28.9
 * path description: given above
 * Goffin's original chart reference: A00_0910

The occultation path:
 * approximate ground width [km]: 110
 * uncertainty [path widths]: 0.7
 * uncertainty in time [s]: 20
 * map: below
 * remarks: Path uncertainities are given according to nominal star
    position errors and expected asteroid positional accuracy.
    !!!!!!!
    Circles along path indicates the centerline for this event.
    They are more accurate than the path limit lines.
    !!!!!!!

Data for the target star:
 * name: SAO 92760 = PPM 91304 = TYC 1213-00825-1
 * constellation: Aries
 * J2000 position [h,m,s; o,',"]: 02h 02m 28.213s; +20o 05' 43.04"
 * position source: Tycho-2
 * estimated accuracy ["]: 0.02" (0.02", 0.02")
 * V mag [mag]: 9.21
 * B-V [mag]: +0.33
 * remarks: 
     Target star is in western Aries, only 2 degrees east of 2.7 mag star
     beta Arietis = SAO 75012. Target star is the easternmost in a very nice 
     equilateral triangle where 9.5 mag star SAO 92757 in NW corner can be 
     used as good reference star for this event.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 3.0x3.0 degrees
 * limiting magnitude is 12.5
 * labeled stars have indicated SAO numbers





Data for the minor planet:
 * general information:
     number, name: (192) Nausikaa
     approx. diameter [km]: 107
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen), 
                                Geneva Obs. (Raoul Behrend)
     number of used observations: 41 USNO, 2 TMO, 8(1) GenO
     number of rejected observations: 5 USNO
     time covered by the observations: 1997 11 30 - 2000 09 19
     rms residuals ["] (RA,DE): 0.09", 0.08"
     estimated positional accuracy at epoch of event ["]: 0.09"
     remarks: For reduction I've computed mean of the 8 Behrend's positions.

Data for the event:
 * UT date and time of least geocentric approach: 00:38.8 UT
 * approx. V mag of minor planet at event [mag]: 9.4
 * geocentric parallax of minor planet ["]: 9.632
 * magnitude drop [mag]: 0.9
 * estimated maximum duration [s]: 28.9
 * apparent motion of minor planet ["/h]: 20.14
 * angular distance to moon, phase of moon [deg,%]: 39, 62%
 * remarks: 

Calculator(s): Jan Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   ........ shortened ..........................
      o  '  "      o  '  "    h  m  s    o     o
   + 19 00 00   + 28 53 28    0 42 56   81   -48
   + 17 00 00   + 31 27 01    0 44 22   78   -47
   + 15 00 00   + 33 53 43    0 45 44   75   -46
   + 13 00 00   + 36 13 21    0 47 02   73   -45
   + 11 00 00   + 38 25 52    0 48 16   70   -45
   +  9 00 00   + 40 31 13    0 49 26   68   -44
   +  7 00 00   + 42 29 30    0 50 31   65   -43
   +  5 00 00   + 44 20 49    0 51 32   63   -41
   +  3 00 00   + 46 05 22    0 52 29   61   -40
   +  1 00 00   + 47 43 23    0 53 22   59   -39
   -  1 00 00   + 49 15 07    0 54 11   57   -38
   -  3 00 00   + 50 40 51    0 54 57   55   -37
   -  5 00 00   + 52 00 54    0 55 40   54   -36
   -  7 00 00   + 53 15 32    0 56 20   52   -35
   -  9 00 00   + 54 25 05    0 56 58   50   -34
   - 11 00 00   + 55 29 49    0 57 33   49   -33
   - 13 00 00   + 56 30 03    0 58 05   47   -32
   - 15 00 00   + 57 26 04    0 58 35   46   -32
   - 17 00 00   + 58 18 06    0 59 04   45   -31
   - 19 00 00   + 59 06 24    0 59 30   43   -30
   - 21 00 00   + 59 51 14    0 59 55   42   -29
   - 23 00 00   + 60 32 47    1 00 19   41   -28
   - 25 00 00   + 61 11 16    1 00 41   40   -28
   ........ 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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