This update is based upon 36 astrometric positions of the asteroid alone obtained by Ron Stone at the U.S. Naval Observatory Flagstaff Station between January 29 and March 25. The update has been computed by Jan Manek, using the Hipparcos and ACT/TRC positions of the star. Manek makes the following important points:

• The target star is the FAINTER component of the double star STF1616. The magnitude of the target star is 9.6 (note that this is brighter than the PPM magnitude given in the original prediction). The brighter component of the pair is magnitude 7.5, at a distance of 23.5" in PA 115 degrees. (The brighter component (HIP 59690) is occulted about 1 hour earlier for observers in the USA).
  
• Two versions of the calculated paths are given below. This is because in this case the Hipparcos star position has unusually large nominal errors. So the ACT/TRC position was used to produce an alternate prediction. I really don't know which path should be better.

Event Summary:

• Target star : HIP 59687 = PPM 158637 = TYC 0866 1182 1
  
• Star Magnitude : 9.63 (Johnson V)
  
• Target star is the FAINTER component of double star STF1616 which is 2.3 degrees west of the 4.1 mag star omicron Virginis.
  
• Hipparcos J2000 position : 12h 14m 25.890s; +08o 47' 06.65"
  
• Hipparcos estimated accuracy : 0.34" (0.28", 0.20")
  
• TRC J2000 position : 12h 14m 25.910s; +08o 47' 06.83"
  
• TRC estimated accuracy : 0.06" (0.04", 0.04")
  
  
• Magnitude drop at occultation : 3.4
  
• Estimated maximum duration : 14.2 secs
  
  

Path Update:

• The HIPPARCOS path runs over north Kalimantan island and ends over the southern Malay peninsula, but strong twilight will probably prevent observations.
  
  
• The ACT/TRC path runs more south over the Solomon Islands, PNG, Sulawesi, south Kalimantan and middle Sumatra (Indonesia; also in strong twilight). The PNG area and Kalimantan are the best sites.
  
  
• Path Uncertainty : 1.2 path widths
  
• Time Uncertainty : 15 seconds
  
• Note however that path uncertainities are given according to the expected asteroidal positional accuracy only. They are valid for each path separately. However additional uncertainities should be added for each star's positional error.
  

IMPORTANT NOTE!

Astrometric updates such as these should not be taken as definitive, but rather only as an indication of where the true track may lie relative to the original predicted track. Observers must bear in mind that later astrometry, in which the target star is measured in the same field as the asteroid, may still reveal substantial changes to the predicted track and time of the event. For this reason it is most important that observers far from the predicted track still monitor the event.