Update for (41) Daphne - July 2/3, 1999

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
              (41) Daphne / SAO 121499 event on 1999, July 2/3
        visible from Spain, France, Belgium, Netherland and Denmark


Summary 

On the night July 2/3, 1999 will be occulted 9.4 mag star by a 182 km asteroid (41) Daphne. This update is based on USNO/Flagstaff and TMO astrometry for asteroid and TRC star position.

This update gives ~0.2 path width west shift and time ~25 seconds earlier compared to Goffin's nominal prediction.

Brighness drop 1.3 magnitudes (well enough for visual observations) and duration almost 40 seconds makes this EVENT VERY PROMISING together with the path location.

Path runs over southern Sweden in twilight ~22:40 UT, over whole Denmark ~22:41 UT, hits very NW Germany with Hannover and Bremen just out of the path. Then almost completely is covered Netherland ~22:42 and Belgium ~30 seconds later with Brussels in path. Later France is crossed with Paris ~22:43 UT and path runs to SW, hitting also Orleans, Tours, Poitiers, Angouleme ~22:44 UT, Bordeaux and Dax ~22:45 UT. After crossing Pyrenee mountains (Pic du Midi on the eastern limit) path runs over Spain with Pamplona in path and Madrid also ~22:46 UT. Sevilla and Malaga are on the western and eastern limit respectively ~22:47 UT. After crossing Gibraltar the path runs over Morocco south. Check the update map for your local chances - keep in mind the possible 0.4 path width uncertainity.

Please spread a note about this favourable event also to your amateur-astronomer friends to get a good coverage of this promising event.

The event at one glimpse:
 * date and approx. UT time of event: July 2, 1999 @ 22:44 UT
 * magnitude of target star: 9.4
 * magnitude drop [mag]: 1.3
 * estimated maximum duration [s]: 38.8
 * path description: Path runs over southern Sweden in twilight ~22:40 UT, over
     whole Denmark ~22:41 UT, hits very NW Germany with Hannover and Bremen just 
     out of the path. Then almost completely is covered Netherland ~22:42 and 
     Belgium ~30 seconds later with Brussels in path. Later France is crossed 
     with Paris ~22:43 UT and path runs to SW, hitting also Orleans, Tours,
     Poitiers, Angouleme ~22:44 UT, Bordeaux and Dax ~22:45 UT. After crossing 
     Pyrenee mountains (Pic du Midi on the eastern limit) path runs over Spain
     with Pamplona in path and Madrid also ~22:46 UT. Sevilla and Malaga are on 
     western and eastern limit respectively ~22:47 UT. After crossing Gibraltar
     the path runs over Morocco south.
     Check the chart below for details and keep in mind the SHADED path is 
     the correct one !

The occultation path:
 * approximate width [km]: 185
 * uncertainty [path widths]: 0.4
 * 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. 
    This time it is also indicated with a gray colour.
    !!!!!!!

Data for the target star:
 * name: SAO 121499 = PPM 162480 = TYC 0380 00670 1
 * constellation: Hercules
 * J2000 position [h,m,s; o,',"]: 16h 19m 22.942s; +05o 43' 19.61"
 * position source: TRC1.0
 * estimated accuracy ["]: 0.02"  (0.02", 0.02")
 * Johnson V mag [mag]: 9.34
 * B-V [mag]: +0.45
 * remarks: TYCHO quality flag is 3 (high) with 'no duplicity' flag set.

     Target star is in very south-west Hercules, 4.7 degrees NW of 3.9 mag star 
     lambda Oph. 11' south of target is 7.6 mag star SAO 121502 and 12' east of 
     target is 8.8 mag star SAO 121512. These form together with the target 
     a nice triangle.
     Be sure to have enough time for finding the correct star.

Data for the minor planet:
 * general information:
     number, name: (41) Daphne
     approx. diameter [km]: 182
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 55 USNO, 23 TMO
     number of rejected observations: 2 USNO (1999 03 24.49754,1999 02 11.56979)
                 3 TMO (1998 12 13.570949, 1998 12 11.569537, 1998 12 11.559803)
     time covered by the observations: 1998 02 12 - 1999 06 28
     rms residuals ["] (RA,DE): 0.07", 0.07"
     estimated positional accuracy at epoch of event ["]: 0.07"
     remarks: 

Data for the event:
 * UT date and time of least geocentric approach: 22:59:29 UT
 * approx. V mag of minor planet at event [mag]: 10.3
 * geocentric parallax of minor planet ["]: 7.030
 * magnitude drop [mag]: 1.3
 * estimated maximum duration [s]: 38.8
 * apparent motion of minor planet ["/h]: 18.61
 * angular distance to moon, phase of moon [deg,%]: 86, 85%
 * remarks: 

Calculator(s): Jan Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
   ......... shortened .........................
   + 17 00 00   + 61 43 49   22 39 46   29    -5
   + 15 00 00   + 60 27 41   22 40 04   31    -7
   + 13 00 00   + 59 03 38   22 40 25   32    -8
   + 11 00 00   + 57 30 46   22 40 49   34    -9
   +  9 00 00   + 55 48 02   22 41 17   36   -11
   +  7 00 00   + 53 54 18   22 41 48   38   -12
   +  5 00 00   + 51 48 24   22 42 24   41   -14
   +  3 00 00   + 49 29 04   22 43 05   43   -16
   +  1 00 00   + 46 55 03   22 43 52   46   -18
   -  1 00 00   + 44 05 10   22 44 46   49   -20
   -  3 00 00   + 40 58 25   22 45 48   53   -23
   -  5 00 00   + 37 34 02   22 46 58   56   -25
   -  7 00 00   + 33 51 37   22 48 18   60   -28
   -  9 00 00   + 29 51 17   22 49 46   64   -31
   - 11 00 00   + 25 33 40   22 51 24   69   -34
   - 13 00 00   + 20 59 57   22 53 11   74   -37
   - 15 00 00   + 16 11 52   22 55 06   79   -40
   - 17 00 00   + 11 11 38   22 57 07   84   -42
   - 19 00 00   +  6 01 51   22 59 14   88   -45
   ......... 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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