Update for (122) Gerda - March 28, 2002 - South Africa

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
              (122) Gerda / TYC 1368-00801-1 on March 28, 2002
                    visible possibly from South Africa

Summary 

In the night of March 28, 2002 a 10.5 mag star TYC 1368-00801-1 will be occulted by a 87 km asteroid (122) Gerda. This update is based on USNO/Flagstaff astrometry for the asteroid and UCAC star position.

The updated path shows no shift with time ~0.2 minutes later compared to Edwin Goffin's nominal prediction.

Updated path runs ~1 path width south of South African coast. On the north limit of possible occultation uncertainty is South African coast with Cape Town around 20:50.5 UT. Please check the path chart for details.

Good luck !

The event at one glimpse:
 * date and approx. UT time of event: March 28, 2002 @ 20:50 UT (South Africa)
 * magnitude of target star: 10.5
 * magnitude drop [mag]: 3.0
 * estimated maximum duration [s]: 9.7
 * path description: given above
 * Goffin's original chart reference: A02_0319

The occultation path:
 * approximate ground width [km]: 125
 * uncertainty [path widths]: 1.5
 * uncertainty in time [s]: 15
 * 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 1368-00801-1
 * constellation: Gemini
 * J2000 position [h,m,s; o,',"]: 07h 31m 55.8056s; +20o 20' 07.918"
 * position source: UCAC combined with Tycho-2 proper motion
 * estimated accuracy ["]: 0.02" (0.020", 0.005")
 * V mag [mag]: 10.46
 * B-V [mag]: +0.28
 * remarks:
    Recent UCAC position was provided by Marion and Norbert Zacharias.
    Target star is in southeast Gemini, about 3.2 degrees SE of 3.5 mag star delta Geminorum.
    Target star is southern one in equal pair, northern one is 57" distant.
    Famous Eskymo nebula NGC 2392 is 52' NW of target.

Close finding chart (prepared in GUIDE7):
 * occulted star is in center - labeled with cross
 * field is 2.0x2.0 degrees
 * limiting magnitude is 13.0
 * labeled stars have indicated SAO numbers
 * remarks:





Data for the minor planet:
 * general information:
     number, name: (122) Gerda
     approx. diameter [km]: 87
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone)
     number of used observations: 116 USNO
     number of rejected observations: 15 USNO
     time covered by the observations: 1998 04 05 - 2002 03 16
     rms residuals ["] (RA,DE): 0.06", 0.07"
     estimated positional accuracy at epoch of event ["]: 0.05", 0.06"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 20:43.2 UT
 * approx. V mag of minor planet at event [mag]: 13.4
 * geocentric parallax of minor planet ["]: 3.258
 * magnitude drop [mag]: 3.0
 * estimated maximum duration [s]: 9.7
 * apparent motion of minor planet ["/h]: 16.47
 * angular distance to moon, phase of moon [deg,%]: 78, 100%
 * 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  '  "
      6  0  0   -32  8 38   20 48 57    30   -40  -32 44 54  -31 32 47
      8  0  0   -32 46 19   20 49 13    28   -42  -33 22 45  -32 10 18
     10  0  0   -33 25 21   20 49 28    27   -43  -34  1 58  -32 49 10
     12  0  0   -34  5 41   20 49 43    25   -44  -34 42 29  -33 29 20
     14  0  0   -34 47 14   20 49 56    23   -45  -35 24 13  -34 10 42
     16  0  0   -35 29 54   20 50  9    22   -46  -36  7  3  -34 53 12
     18  0  0   -36 13 36   20 50 20    20   -47  -36 50 56  -35 36 43
     20  0  0   -36 58 14   20 50 31    18   -47  -37 35 44  -36 21 11
     22  0  0   -37 43 42   20 50 41    17   -48  -38 21 23  -37  6 29
     24  0  0   -38 29 54   20 50 49    15   -48  -39  7 45  -37 52 31
     26  0  0   -39 16 44   20 50 57    13   -49  -39 54 46  -38 39 12
     28  0  0   -40  4  7   20 51  4    12   -49  -40 42 18  -39 26 26
     30  0  0   -40 51 56   20 51 10    10   -49  -41 30 16  -40 14  6
     32  0  0   -41 40  5   20 51 15     8   -49  -42 18 34  -41  2  6
     34  0  0   -42 28 27   20 51 18     7   -49  -43  7  5  -41 50 20
   ........................... 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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