The Pamina and Ostena Asteroid Occultations
of June 7, 2008
At the end of final exams week, this
double asteroid occultation criss crossed through the Coalinga area early Saturday
morning. David Dunham was in town, to set up several unmanned stations in addition
to his own. Walt Morgan and other local observers also planned to set up stations
for this. The Pamina path also crossed through the Phoenix and Tucson areas
and so there were many observers lined up to get this one. Ostena was a tiny
asteroid, only 22km, and the path precision was not great, but the star was
bright - magnitude 6.5. This helped draw out the California asteroid occultationists.
The Pamina event probability for our location was about 50/50, while Ostena
was only 1 chance in 4. So part of the attraction for me was the extremely dark
skies there and a couple of hours to do astrophotography first.
Chris Kitting (CSUEB marine biology
professor and long time friend) joined me for this event, taking a day off from
his mollusk conference in Monterey to help do some astro science. His goal was
also to get some additional practice and testing done with his image intensified
coupled with his telephoto lens and camcorder. A good thing, as it saved our
Ostena event as it turned out. On the drive down, I stopped at the King City
Taco Bell for dinner. Then to Hwy 198 and east to Parkfield Grade road, and
a bit of scouting to insure a location that would have a good horizon for the
17 degree elevation Ostena occultation.
Chris, in safari gear. We're packing up
my RAV4 at Cabrillo Observatory
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Setting up our scopes in a creek bed in
range land along Parkfield Grade road
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Antares and the Rho Ophiuchi Complex.
8x10min stack with the 50mm
Zuiko lens + UV/Haze filter, on ST2000XCM under clean skies. Color balanced
more toward blue to take out reddening due to low altitude, along with
the usual Photoshop and AstroTools favorites
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Cabrillo's 10" LX200 w/ Meade f/3.3
focal reducer on alt-az mount, equipped with a PC 164c video camera
and Kiwi II VTI and ZR 45MC camcorder recording device. The Pamina occultation
target star was only 1 degree away from Jupiter, speeding identification
of this faint 12th magnitude star.
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The other people pix here were all taken
with my Dimage A1. This one here was taken with Chris' Nikon D300. Much
much improved (....but those D300's are very pricey!)
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I had trouble locating the rising 10 Ceti
target star for the Ostena Occulation and ended up watching the next
closest star - Doh! Chris saved the day by recording the event using
his telephoto lens and I3 image intensifier.
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Chris' tape showed strong scintillation of the Ostena target star, but the
star did not disappear during the10:49:48 predicted time or several sigma before
or after. However, there was one perhaps unusually long disappearance at 10:50:10.
In his words... "The apparent disappearance of that star was at 10:50:10
to 11 sec (closer to 11 sec, for ~1/2 sec), based on the WWV sound track. Individual
video frames were too noisy to analyze frame by frame, alas. It is possible
that the noise simply overwhelmed the star at that moment, causing the apparent
(and subtle, brief) disappearance." After the event, I used bino's to help
spotlight the star with the laser pointer so Chris could videorecord it and
positively ID the star for later analysis. Then, we packed up at dawn and started
the long drive home. I did stop once before we got on Hwy 101, for a 15 minute
nod-off. Made it home w/o incident. An all-nighter!
Here is a
sky-plane plot of all Pamina observations.
