Update for (386) Siegena - May 11/12, 1999

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
             (386) Siegena / SAO 123068 event on 1999, May 11/12
                              visible from Africa


Summary 

On the night May 11/12, 1999 will be occulted 8.9 mag star by a 173km asteroid (386) Siegena. This update is based on USNO/Flagstaff and TMO astrometry for asteroid and ACT star position.

This update gives NO path shift and time about 0.1 minutes later compared to the Goffin's nominal prediction.

The event at one glimpse:
 * date and approx. UT time of event: May 11, 1999 @ 23:49 UT
 * magnitude of target star: 8.9
 * magnitude drop [mag]: 3.7
 * estimated maximum duration [s]: 17.7
 * path description: Path runs over Africa and north of Canary Islands at
     ~23:49 UT. European observers practically have no chance to see the
     main event.

The occultation path:
 * approximate width [km]: 180
 * uncertainty [path widths]: 1
 * uncertainty in time [s]: 20
 * map: attached
 * 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 123068 = PPM 165080 = TYC 0438 00092 1
 * constellation: Ophiuchus
 * J2000 position [h,m,s; o,',"]: 18h 03m 26.082s; +03o 51' 05.93"
 * position source: ACT
 * estimated accuracy ["]: 0.03"  (0.01", 0.02")
 * Johnson V mag [mag]: 8.93
 * B-V [mag]: +0.55
 * remarks: Target star is in eastern part of Ophiuchus constellation;
     it is 56' SE of 4.8 mag star 66 Oph or 68' NE of 4.0 mag star 67 Oph.
     Be sure to have enough time for finding the correct star.

Data for the minor planet:
 * general information:
     mumber, name: (386) Siegena
     approx. diameter [km]: 173
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 30 USNO, 9 TMO
     number of rejected observations: 1 USNO (1998 05 11.217508)
     time covered by the observations: 1998 02 12 - 1999 05 06
     rms residuals ["] (RA,DE): 0.07", 0.07"
     estimated positional accuracy at epoch of event ["]: 0.08"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 23:39:54 UT
 * approx. V mag of minor planet at event [mag]: 12.6
 * geocentric parallax of minor planet ["]: 3.695
 * magnitude drop [mag]: 3.7
 * estimated maximum duration [s]: 17.7
 * apparent motion of minor planet ["/h]: 20.38
 * angular distance to moon, phase of moon [deg,%]: 91, 18%
 * remarks:

Calculator(s): Jan Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   ...... shortened ............................
   + 14 00 00   + 17 28 30   23 45 26   57   -53
   + 12 00 00   + 18 56 53   23 45 48   54   -52
   + 10 00 00   + 20 21 16   23 46 10   52   -51
   +  8 00 00   + 21 41 39   23 46 30   50   -50
   +  6 00 00   + 22 58 06   23 46 49   48   -49
   +  4 00 00   + 24 10 39   23 47 07   46   -48
   +  2 00 00   + 25 19 22   23 47 24   44   -47
   +  0 00 00   + 26 24 19   23 47 40   42   -46
   -  2 00 00   + 27 25 36   23 47 56   40   -45
   -  4 00 00   + 28 23 16   23 48 10   38   -43
   -  6 00 00   + 29 17 26   23 48 23   36   -42
   -  8 00 00   + 30 08 10   23 48 36   34   -41
   - 10 00 00   + 30 55 33   23 48 48   32   -40
   - 12 00 00   + 31 39 40   23 48 59   30   -39
   - 14 00 00   + 32 20 36   23 49 09   29   -38
   - 16 00 00   + 32 58 26   23 49 19   27   -36
   - 18 00 00   + 33 33 14   23 49 28   25   -35
   - 20 00 00   + 34 05 04   23 49 36   23   -34
   - 22 00 00   + 34 34 00   23 49 44   22   -33
   - 24 00 00   + 35 00 06   23 49 51   20   -32
   - 26 00 00   + 35 23 24   23 49 57   18   -31
   - 28 00 00   + 35 43 58   23 50 03   17   -30
   - 30 00 00   + 36 01 50   23 50 08   15   -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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