Update for (3) Juno - May 24/25, 2000

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
       (3) Juno / TYC 5212-00753-1 = SAO 145458 event on May 24/25, 2000
                    visible from central and NE Europe


Summary 

In the night of May 24/25, 2000 a 9.5 mag star TYC 5212-00753-1 = SAO 145458 will be occulted by a large 267 km asteroid (3) Juno. This update is based on USNO/Flagstaff, TMO and Hipparcos astrometry for the asteroid and Tycho-2 star position.

The updated path shows ~0.2 path width east shift with time ~0.2 minutes later compared to Edwin Goffin's nominal prediction (which is well within update errors).

The path of this occultation runs over very large part of the Europe. The path is almost grazing Earth globe so the path projection on ground is very wide and the star altitude is very low. Chances for observing where the star will be more than ~5 degrees high are in northern Italy and Switzerland at ~23:38.5 UT, Austria, Hungary and S Germany ~23:38.8 UT, Czech Republic and Slovakia ~23:39 UT, maybe eastern parts of middle and north Germany, surely Poland and western Ukraina around 23:39.5 UT, Belarus and Lithuania at ~23:40 UT, Latvia, Estonia, NW Russia with St.Peterburg and southern Finland at ~23:41 UT - here also twilight will be a complication.

Be sure to select a site with free horizon to the east and surely try to locate the star at similar altitude a day or two before the event. Brightness drop is expected to be 1.2 magnitudes, which is enough for visual observers. Use the neighbouring star SAO 145450 as a reference star. Due to altitude and scintillation it may be a hard observation, so CCD scans or video records are recommended. Moon will be no problem although it is only 16 degrees distant, because at the time of the event it will just rising.

No recent observation are available, however orbit solution is good enough to encourage observers to give a try, despite of the low altitude.

The event at one glimpse:
 * date and approx. UT time of event: May 24, 2000 @ 23:40 UT
 * magnitude of target star: 9.5
 * magnitude drop [mag]: 1.2
 * estimated maximum duration [s]: 21.8
 * path description: given above
 * Goffin's original chart reference: A00_0501

The occultation path:
 * approximate ground width [km]: 1100
 * uncertainty [path widths]: 0.6
 * 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: PPM 205298 = SAO 145458 = TYC 5212-00753-1
 * constellation: Aquarius
 * J2000 position [h,m,s; o,',"]: 21h 31m 33.909s; -03o 04' 50.98"
 * position source: Tycho-2
 * estimated accuracy ["]: 0.04 (0.03", 0.03")
 * V mag [mag]: 9.54
 * B-V [mag]: +1.10
 * remarks: 
     Target star is in mid-west Aquarius, 2.5 degrees almost exactly north 
     of a 2.9 mag star beta Aquarii. There is good brightness reference star
     SAO 145450 (mag 9.4) only 6.7' WNW of target for this event with not 
     very large brightness drop.

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: (3) Juno
     approx. diameter [km]: 267
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen),
                                Hipparcos
     number of used observations: 55 USNO, 8 TMO, 69 Hipparcos
     number of rejected observations: 2 USNO
     time covered by the observations: 1990 01 17 - 1999 07 18
     rms residuals ["] (RA,DE): 0.06", 0.07"
     estimated positional accuracy at epoch of event ["]: 0.07"
     remarks: No recent observations are available. However as the excellent
       observations cover almost 10 years, the orbit should be good enough
       to give a reliable update.

Data for the event:
 * UT date and time of least geocentric approach: 23:40.7  UT
 * approx. V mag of minor planet at event [mag]: 10.3
 * geocentric parallax of minor planet ["]: 3.586
 * magnitude drop [mag]: 1.2
 * estimated maximum duration [s]: 21.8
 * apparent motion of minor planet ["/h]: 24.83
 * angular distance to moon, phase of moon [deg,%]: 16, 66%
 * remarks: 

Calculator(s): Jan Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
      o  '  "     o  '  "    h  m  s     o     o
   ........ shortened ..........................
      6  0  0    47 25 52   23 38 31     5   -22
      7  0  0    47 32 47   23 38 33     6   -22
      8  0  0    47 41  3   23 38 36     6   -21
      9  0  0    47 50 42   23 38 38     7   -21
     10  0  0    48  1 45   23 38 41     7   -21
     11  0  0    48 14 13   23 38 45     8   -21
     12  0  0    48 28  8   23 38 48     9   -20
     13  0  0    48 43 32   23 38 52     9   -20
     14  0  0    49  0 28   23 38 57    10   -20
     15  0  0    49 18 57   23 39  1    10   -19
     16  0  0    49 39  3   23 39  6    11   -19
     17  0  0    50  0 49   23 39 11    11   -18
     18  0  0    50 24 18   23 39 16    12   -18
     19  0  0    50 49 36   23 39 22    12   -17
     20  0  0    51 16 47   23 39 28    13   -17
     21  0  0    51 45 58   23 39 34    13   -16
     22  0  0    52 17 16   23 39 41    14   -15
     23  0  0    52 50 51   23 39 48    14   -15
     24  0  0    53 26 53   23 39 55    14   -14
     25  0  0    54  5 38   23 40  3    14   -13
     26  0  0    54 47 23   23 40 11    15   -12
     27  0  0    55 32 34   23 40 20    15   -11
     28  0  0    56 21 44   23 40 29    15   -10
     29  0  0    57 15 43   23 40 39    15    -9
     30  0  0    58 15 46   23 40 49    15    -8
     31  0  0    59 24  5   23 41  0    15    -7
     32  0  0    60 44 59   23 41 13    14    -5
   ........ 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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