Update for (1000) Piazzia - January 20, 2000

Jan Manek's update

                     IOTA/IOTA-ES occultation update for
           (1000) Piazzia / SAO 39283 event on January 20, 2000
            visible from Greenland, Iceland, Ireland and Spain


Summary 

In the evening January 20, 1999 a 8.8 mag star TYC 2889 01999 1 = SAO 39283 will be occulted by a small 54 km asteroid (1000) Piazzia. This update is based on USNO/Flagstaff astrometry for the asteroid and ACT star position.

The updated path shows large ~0.7" west shift with time ~0.4 minutes later compared to Edwin Goffin's nominal prediction.

The path of this occultation runs over Greenland ~17:42 UT, Iceland ~17:43 UT, Ireland ~17:45 UT and Spain ~17:47 UT. However the uncertainities are extremely large this time and within errors is also whole Scotland and England ~17:45 UT and western France ~17:46 UT.

The event at one glimpse:
 * date and approx. UT time of event: January 20, 2000 @ 17:45 UT
 * magnitude of target star: 8.8
 * magnitude drop [mag]: 7.1
 * estimated maximum duration [s]: 4.6
 * path description: given above
 * Goffin's original chart reference: A00_0131(.PS.GZ).

The occultation path:
 * approximate ground width [km]: 55
 * uncertainty [path widths]: 9
 * uncertainty in time [s]: 45
 * 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: SAO 39283 = PPM 46758 = TYC 2889 01999 1
 * constellation: Perseus
 * J2000 position [h,m,s; o,',"]: 04h 03m 54.538s; +43o 38' 35.94"
 * position source: ACT
 * estimated accuracy ["]: 0.02" (0.01", 0.01")
 * V mag [mag]: 8.83
 * B-V [mag]: +0.57
 * remarks: TYCHO gives quality flag 3(=high) with 'no duplicity' flag. 

     Target star is in middle Perseus, about 3.6 degrees NE of 3.8 mag star 
     nui Persei. There is 7.4 mag star SAO 39312 ~30.5' ESE of target.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 1.5x1.5 degrees
 * limiting magnitude is 12.5
 * labeled stars have indicated SAO numbers





Data for the minor planet:
 * general information:
     number, name: (1000) Piazzia
     approx. diameter [km]: 54
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone)
     number of used observations: 30 USNO
     number of rejected observations: 3 USNO
     time covered by the observations: 1998 08 26 - 2000 01 11
     rms residuals ["] (RA,DE): 0.18", 0.18"
     estimated positional accuracy at epoch of event ["]: 0.20"
     remarks: RMS errors are unusually large this time, the asteroid was
       very faint all the time.

Data for the event:
 * UT date and time of least geocentric approach: 17:46:12 UT
 * approx. V mag of minor planet at event [mag]: 8.8
 * geocentric parallax of minor planet ["]: 2.659
 * magnitude drop [mag]: 7.1
 * estimated maximum duration [s]: 4.6
 * apparent motion of minor planet ["/h]: 17.57
 * angular distance to moon, phase of moon [deg,%]: 50, 100%
 * remarks: 

Calculator(s): Jan Manek






Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
  not given due to N-S path direction OCCULT limitation

----------------------------------------------------------------------------
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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