Update for (91) Aegina - May 1/2, 2002

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
            (91) Aegina / TYC 6197-00761-1 on May 1/2, 2002
                     NOT visible from anywhere


Summary 

In the night of May 1/2, 2002 a faint 12.1 mag star TYC 6197-00761-1 will be occulted by a 114 km asteroid (91) Aegina. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and combined Tycho-2/UCAC star position.

The updated path shows ~3 path width north shift with time ~0.5 minutes earlier compared to Edwin Goffin's nominal prediction.

Updated path almost miss the Earth, only south limit touches sunlit ground. Even within uncertainty the path runs in twilight zone. So in fact I don't see any chance to observe this event. Sorry. Please check the path chart for details.

The event at one glimpse:
 * date and approx. UT time of event: May 2, 2002 @ 01:33 UT
 * magnitude of target star: 12.1
 * magnitude drop [mag]: 1.2
 * estimated maximum duration [s]: 9.9
 * path description: given above
 * Goffin's original chart reference: A02_0509

The occultation path:
 * approximate ground width [km]: ---
 * uncertainty [path widths]: 0.7
 * uncertainty in time [s]: 9
 * map: below
 * remarks: Path uncertainties are given according to nominal star
    position errors and expected asteroid positional accuracy.

Data for the target star:
 * name: TYC 6197-00761-1
 * constellation: Libra
 * J2000 position [h,m,s; o,',"]: 15h 38m 38.0877s; -21o 39' 43.562"
 * position source: UCAC1
 * estimated accuracy ["]: 0.03" (0.025", 0.015")
 * V mag [mag]: 12.14
 * B-V [mag]: +0.61
 * remarks:
    Target star is in southeast Libra, about 5 degrees west of 2.3 mag star delta Scorpii = SAO 184014.
    Target star is 4' south of 8.3 mag star SAO 183650.
    Purple stars in identification chart are so called 'non-star' objects in GSC; in dense fields
    the 'non-stars' are often real stars or blends of close pairs. Be careful.

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
 * remarks:





Data for the minor planet:
 * general information:
     number, name: (91) Aeginae
     approx. diameter [km]: 114
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 82 USNO, 2 TMO
     number of rejected observations: 9 USNO
     time covered by the observations: 1998 03 22 - 2002 04 23
     rms residuals ["] (RA,DE): 0.07", 0.09"
     estimated positional accuracy at epoch of event ["]: 0.05", 0.05"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 01:33.1 UT
 * approx. V mag of minor planet at event [mag]: 12.9
 * geocentric parallax of minor planet ["]: 4.800
 * magnitude drop [mag]: 1.2
 * estimated maximum duration [s]: 9.9
 * apparent motion of minor planet ["/h]: 31.29
 * angular distance to moon, phase of moon [deg,%]: 48, 72%
 * remarks:

Calculator(s): Jan Manek





Path coordinates:
                                                   Latitude   Latitude
                  Center               Altitude       Path Limits
  E. Longitude   Latitude      U.T.   star   sun   Limit 1    Limit 2
   ........................... shortened .............................
      o  '  "     o  '  "    h  m  s     o     o    o  '  "    o  '  "
     16  0  0    .. .. ..   .. .. ..    ..    ..   .. .. ..   65 37 53
     18  0  0    .. .. ..   .. .. ..    ..    ..   .. .. ..   65 51 11
   ........................... 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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