From Sky & Telescope "AstroAlert"
dated September 24, 2007
On September 27, 2007, around 14.8h Universal Time, Pluto passes
extremely close to an 8.7-magnitude star, SAO 160793, in Sagittarius (see the
chart on page 60 of the July Sky & Telescope). This is the brightest star
approached so closely by Pluto since predictions of occultations by this dwarf
planet were first made over 30 years ago. Earth will actually pass "between
the shadows" of Pluto and its moon Charon, with no occultation by either
object visible from Earth's surface. But occultations by possible Plutonian
rings might be observed from the night areas of most of Asia (from Arabia to
Vietnam to western and southern China to the Ural Mountains), the Horn of
Africa, western Australia, part of Antarctica, and the Indian Ocean. Observers
in those and adjacent areas, such as Japan, eastern Australia, New Zealand, and
South Africa, are encouraged to record the star with CCD, video, or photometric
equipment for a few hours around the time of closest approach; such records can
be analyzed later to find evidence of any fadings of the star's light that might
be due to Plutonian rings; these would be of great interest to scientists
involved with the New Horizons mission to Pluto.
Walker Vaning of San Rafael, California, claims that observations of past occultations show that Pluto has an extensive ring system, and that it could cause fadings of SAO 160793's light even more than 12 hours from the time of closest approach. So he encourages observers worldwide to monitor the star while it is high enough above the local horizon in a dark sky. He thinks that very distant rings may exist that could pass over the star even 3 days from the time of Pluto's closest approach.
The star is also known as BD –16° 4607, P507, and UCAC2 25587116. It is at right ascension 17h 44m 38.4s, declination –16° 46' 35" (equinox 2000.0), and its spectral type is K5.
More info on MIT
website.