Update for (284) Amalia - November 18/19, 1999

Jan Manek's update

                     IOTA/IOTA-ES occultation update for
        (284) Amalia / TYC 1333 01580 1 event on November 18/19, 1999
              visible from Romania, former Yugoslavia, N Italy, 
                         S France, Spain and Portugal


Summary 

In the (morning of) night November 18/19, 1999 a 10.5 mag star TYC 1333 01580 will be occulted by a small 55 km asteroid (284) Amalia. This update is based on USNO/Flagstaff astrometry for the asteroid and ACT star position.

The updated path shows ~9 path width north shift with time ~0.3 minutes later compared to Edwin Goffin's nominal prediction.

The path now runs over Romania at ~4:01.5 UT, former Yugoslavia ~4:03 UT, north Italy with Bologna ~4:03.5 UT, along Meditterian coast of France with Nice and Marseille at ~4:04.5 UT, Pyrenei Mountains close to Pic du Midi ~4:05 UT, northern Spain with Valladolid ~4:06 UT and north Portugal south of Porto at ~4:06.5 UT. Within expected errors are also other places, please check the charts. If we will have luck a good coverage could be obtained.

In this case about two-thirds of uncertainity can be accounted to asteroid position uncertainity and full one-third (or full one path width) due to uncertain star position.

The event at one glimpse:
 * date and approx. UT time of event: November 19, 1999 @ 04:04 UT
 * magnitude of target star: 10.5
 * magnitude drop [mag]: 4.1
 * estimated maximum duration [s]: 6.6
 * path description: given above

The occultation path:
 * approximate ground width [km]: 60
 * uncertainty [path widths]: 3
 * 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: TYC 1333 01580 1
 * constellation: Gemini
 * J2000 position [h,m,s; o,',"]: 06h 36m 52.435s; +17o 17' 46.39"
 * position source: ACT
 * estimated accuracy ["]: 0.05" (0.03", 0.04")
 * V mag [mag]: 10.49
 * B-V [mag]: +0.23
 * remarks: TYCHO gives quality flag 4 (=high) with 'no investigation
     for duplicity' flag.

     Target star is in SW Gemini, only 55' north of 2.0 mag star gamma
     Geminorum. Only 3' SW of target is 10.5 mag star GSC 1333.1597 which
     can serve as a good reference star.

Data for the minor planet:
 * general information:
     number, name: (284) Amalia
     approx. diameter [km]: 55
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone)
     number of used observations: 37 USNO
     number of rejected observations: 2 (1999 11 05.46689,1998 11 23.043075)
     time covered by the observations: 1998 06 07 - 1999 11 14
     rms residuals ["] (RA,DE): 0.07", 0.06"
     estimated positional accuracy at epoch of event ["]: 0.07"
     remarks: 

Data for the event:
 * UT date and time of least geocentric approach: 04:10:13 UT
 * approx. V mag of minor planet at event [mag]: 14.6
 * geocentric parallax of minor planet ["]: 4.410
 * magnitude drop [mag]: 4.1
 * estimated maximum duration [s]: 6.6
 * apparent motion of minor planet ["/h]: 20.79
 * angular distance to moon, phase of moon [deg,%]: 100, 76%
 * remarks: 

Calculator(s): Jan Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   ........ shortened ..........................
   + 40 00 00   + 45 32 13    4 00 29   34    -4
   + 38 00 00   + 45 35 43    4 00 40   35    -6
   + 36 00 00   + 45 37 52    4 00 52   37    -7
   + 34 00 00   + 45 38 39    4 01 03   38    -8
   + 32 00 00   + 45 38 06    4 01 15   39   -10
   + 30 00 00   + 45 36 13    4 01 28   41   -11
   + 28 00 00   + 45 32 59    4 01 40   42   -12
   + 26 00 00   + 45 28 24    4 01 53   43   -13
   + 24 00 00   + 45 22 29    4 02 07   45   -15
   + 22 00 00   + 45 15 14    4 02 20   46   -16
   + 20 00 00   + 45 06 37    4 02 34   47   -17
   + 18 00 00   + 44 56 40    4 02 49   48   -19
   + 16 00 00   + 44 45 21    4 03 03   50   -20
   + 14 00 00   + 44 32 41    4 03 19   51   -21
   + 12 00 00   + 44 18 38    4 03 34   52   -23
   + 10 00 00   + 44 03 14    4 03 50   54   -24
   +  8 00 00   + 43 46 26    4 04 06   55   -26
   +  6 00 00   + 43 28 16    4 04 23   56   -27
   +  4 00 00   + 43 08 41    4 04 40   57   -28
   +  2 00 00   + 42 47 43    4 04 57   58   -30
   +  0 00 00   + 42 25 20    4 05 15   60   -31
   -  2 00 00   + 42 01 32    4 05 33   61   -33
   -  4 00 00   + 41 36 19    4 05 51   62   -34
   -  6 00 00   + 41 09 40    4 06 10   63   -36
   -  8 00 00   + 40 41 35    4 06 29   64   -37
   - 10 00 00   + 40 12 03    4 06 49   65   -39
   - 12 00 00   + 39 41 06    4 07 09   66   -40
   - 14 00 00   + 39 08 42    4 07 29   67   -42
   ........ 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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