Update for (1069) Planckia - February 25, 1999

Jan Manek's update

                      IOTA/IOTA-ES occultation update for
            (1069) Planckia / TYC 1329 00405 event on 1999, February 25
    visible from Portugal, NW Spain, Great Britain, Norway, Sweden and N Finland


Summary 

On the night February 25, 1999 will be occulted 8.5 mag star by a small 43km asteroid (1069) Planckia. This update is based on TMO and Rui Goncalves's astrometry for asteroid and ACT star position. The target star should be easy to locate as it is 1.23 degrees exactly south of bright 2.0 mag gamma Gem (Alhena).

The calculation shows path about two path widths east and about 2.5 minutes earlier compared with the Goffin's nominal prediction.

This path location is based on TMO astrometry from September/October 1998. Rui Goncalves provided additional astrometry from his 10 CCD images with star reference frame based on USNO A2.0 catalogue. I have computed O-C's for his positions and they within the supposed 0.3" accuracy of A2.0 catalogue confirm the earlier TMO observations, however I have not included them in the final calculation because I wasn't sure about the nature of the remaining difference. Including them shifts the path westward and using only Rui's positions put the path over central Ireland.

The event at one glimpse:
 * date and approx. UT time of event: February, 25, 1999 @ 22:26 UT
 * magnitude of target star: 8.5
 * magnitude drop [mag]: 5.8
 * estimated maximum duration [s]: 6.6
 * path description: Path runs over Portugal coast ~22:24 UT, very NW part of 
     Spain ~22:25 UT, possibly also Bretagne in France and England ~22:27 UT, 
     Norway, middle and north Sweden and north Finland ~22:29 - 22:31 UT.
     Uncertainities are large so observers within 0.2" of path may try to observe.

The occultation path:
 * approximate width [km]: 45
 * uncertainty [path widths]: 8
 * uncertainty in time [s]: 60
 * map: attached
 * remarks: Path uncertainities are given according to nominal star position 
    errors and expected asteroid positional accuracy. 

Data for the target star:
 * name: SAO 95915 = PPM 122773 = TYC 1329 00405 1
 * constellation: Gemini
 * J2000 position [h,m,s; o,',"]: 06h 37m 42.556s; +15o 10' 08.74"
 * position source: ACT
 * estimated accuracy ["]: 0.02"  (0.02", 0.01")
 * V mag [mag]: 8.47
 * B-V [mag]: +0.63
 * remarks: Target star is 1.23 degrees exactly south of bright 2.0 mag gamma 
     Gem (Alhena). There is also 9.0 mag SAO 95906 just 2' NW of target star.
     The magnitude given is Johnson V mag. 
     TYCHO quality flag is 3 indicating HIGH quality position.

Data for the minor planet:
 * general information:
     mumber, name: (1069) Planckia
     approx. diameter [km]: 43
 * orbital information
     orbit source: Bowell
     source of used astrometry: TMO (Bill Owen), Rui Goncalves
     number of used observations: 6 TMO, 10 Goncalves
     number of rejected observations: 0
     time covered by the observations: 1998 09 29 - 1999 02 20
     rms residuals ["] (RA,DE): 0.08", 0.06" (for TMO)
     estimated positional accuracy at epoch of event ["]: 0.20"
     remarks: 

Data for the event:
 * UT date and time of least geocentric approach: 22:16:42 UT
 * approx. V mag of minor planet at event [mag]: 14.3
 * geocentric parallax of minor planet ["]: 3.822
 * magnitude drop [mag]: 5.8
 * estimated maximum duration [s]: 6.6
 * apparent motion of minor planet ["/h]: 13.99
 * angular distance to moon, phase of moon [deg,%]: 6, 80%
 * remarks: 

Calculator(s): Manek





Path coordinates:
                                       Altitude
  E. Longitude    Latitude     U.T.    star  sun
  Not possible to compute in OCCULT due to almost South-North path.

----------------------------------------------------------------------------
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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