Lydia
Site Admin
Posted:
Mon Sep 24, 2007 12:00 pm
Joined: 03 Feb 2004
Posts: 589
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Message from David Dunham of I.O.T.A.
Anyone in the listed areas interested in trying this?
LL
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On September 27, 2007, around 14.8h UT, Pluto passes extremely
close to an 8.7-magnitude star, SAO 160793. 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 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
Vanning, San Rafael, California, claims that observations of past
occultations show that Pluto has an extensive ring system that could
cause fadings of SAO 160793's light even more than 12h from the time
of closest approach, so he encourages observers worldwide to monitor
the star while it is high enough above the local horizon; he thinks
that very distant rings may exist that could pass over the star even
3 days from the Pluto closest approach time. The star, also known
as B.D. -16 deg. 4607, P507, and UCAC2 25587116, is at J2000
position is R.A. 17h 44m 38.4s, Dec. -16 deg. 46' 35"; its spectral
type is K5.
This event was mentioned in a Sky and Telescope Astroalert at
http://www.skyandtelescope.com/resources/proamcollab/astroalert/AstroAlert2007May11.html
and information about it is also given at the Massachusetts
Institute of Technology's Web site at
http://occult.mit.edu/research/occultations/Pluto/P507-preds/
David Dunham
2007 September 24
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