A very close appulse of Pluto with GSC 5651-1553 will occur on 01 July
2002, at approximately 23:00 UT.
The event was discovered by Arizona amateur astronomer and Sky & Telescope
Contributing Editor Jeff Medkeff from his home in Sierra Vista. He was
using SkyMap Pro 7.0 software to search for appulses of Pluto past stars in
order to find favorable observing opportunities through the next 14 months.
After initially confirming the event with the Chapront and Francou
Planetary Series (1996) planetary theory, and several other software
packages, he alerted Jet Propulsion Laboratory scientist Bill Owen of the
event. The event geometry is dependent upon three primary variables – the
uncertainty in the position of the star, the uncertainty in the position of
Pluto, and the theory used to describe Pluto’s motion. Using the position
of this star from the Tycho-II catalog, Owen’s preliminary prediction
suggests that the nominal event will have Pluto passing 1/3 arcsecond north
of the star, with Charon 0.84 arcseconds south of Pluto – so that the star
passes between the two. The uncertainties involved are sufficient that
there is a very slim possibility that Pluto will occult the star.
According to Owen, recent astrometry of Pluto obtained independently by Ron
Stone (USNO) and by Owen will be used by Myles Standish (JPL) to update
Pluto’s orbit. If the updated orbit does not rule out an event, additional
astrometry will be pursued to further refine the predictions.
In any case, the event will provide an unusual opportunity for amateur
observers to see Pluto exceptionally close to a field star.
