[sac-forum] Re: Two Pleiades stars occulted last night (?) -- Doin's at SAC ATM
- From: "RAY M VORBECK" <rvorbeck@xxxxxxx>
- To: <sac-forum@xxxxxxxxxxxxx>
- Date: Fri, 6 Feb 2009 22:22:14 -0700
It was my telescope that was collimated by the "SAC Optics Team". As near as I
have been able to tell, this scope was made in 1984 and is a 2080 LX and was
the first LX series scope made. I was shocked by the great improvement the
collimation made. I thought maybe the secondary was hanging loose as all I was
seeing were a bunch of comets when I should have been seeing stars They did a
great job and it was greatly appreciated. It was my first time at the ATM
meeting also.
Ray Vorbeck
----- Original Message -----
From: Jimmy Ray<mailto:jimmy_ray@xxxxxxx>
To: sac-forum@xxxxxxxxxxxxx<mailto:sac-forum@xxxxxxxxxxxxx>
Sent: Wednesday, February 04, 2009 11:41 AM
Subject: [sac-forum] Re: Two Pleiades stars occulted last night (?) -- Doin's
at SAC ATM
The "SAC Optics Team" looking like a Three Stooges Shtick out there!?! (Yea,
we resembled that!)
Was great fun over a Paul's last night. Was a first time for me, highly
educational, glad I went!
Jimmy Ray
-----Original Message-----
From: sac-forum-bounce@xxxxxxxxxxxxx<mailto:sac-forum-bounce@xxxxxxxxxxxxx>
[mailto:sac-forum-bounce@xxxxxxxxxxxxx]
On Behalf Of Gene A Lucas
Sent: Wednesday, February 04, 2009 10:42 AM
To: SAC FORUM; Randy Peterson
Subject: [sac-forum] Two Pleiades stars occulted last night (?) -- Doin's at
SAC ATM
Greetings,
At the SAC ATM meeting at Paul Lind's house last night, Jimmy Ray set up
his binocular mirror viewer in the driveway, and we looked at the Moon
with his 9x60 binos. There were two bright stars near the Moon... this
was about 8 pm, I think.... Got me wondering... after a bit I realized,
the Pleiades grazes predicted on "Feb. 4th" were LAST NIGHT, Feb. 3rd
MST -- the ol' UT time thing again!! The two grazing occultations were
predicted to be visible in the vicinity of Casa Grande, well south of
us, just at sunset.... I looked for, but did not spot, the star that was
predicted to be occulted ca. 10:30 pm. Probably could not find it
because of the streetlights around Paul's house. There is a long series
of Pleiades occultations this year, but not many grazes close to
Phoenix... These two last night were unfavorable, due to the time, and
the later one was for a rather "flat" profile, and would have been
visible near Tucson, probably not worthwhile driving that far. Total
lunar occultations and grazes are still worth observing and timing.
Predictions are available from the IOTA web pages.
Other doin's....
We set up and did a Foucault test on the 1995 Pierre Schwaar mirror from
the EVAC 12.5 inch DOB telescope (which I am now Custodian for)... Paul
Lind entered the test readings into his software, and printed out a nice
graphical plot. (Thanks, Paul !) The test showed that, overall, it is
an averaged 1/7 th wave mirror, with a calculated Strehl ratio of 0.9164
(meaning, about 92 percent of the light is focused into the center of
the Airy disk, or a very good reading). The most important finding was
that the mirror is very smooth, with no bad zones or other adverse
indications. Measured R.O.C. is 131.8 inches, for a focal length of 65.9
inches, and an f: ratio of 5.27. It is a full-thickness (2 inches)
Pyrex mirror, 12.5 inch diameter, good polish all the way to the edge.
From the discussion and some sketched diagrams, Jimmy Ray gradually
came to understand the ideas behind the Foucault test and interpretation
of the shadows... Nothing like a "hands on" optics demonstration !
Dave Fredericksen was pleased with the yellow paint on the upper tube
section I brought along... (If you have seen his huge pickup truck, you
would understand...) I will be doing some work on the scope to improve
it a bit, and will try to bring that out to star parties as frequently
as I can. I had it assembled and in operation up at the EVAC
Boyce-Thompson two weekends ago, and it performed nicely. Good views of
the Pleiades with a 56mm Super Plossl eyepiece -- I spotted the Merope
nebula easily.
Another fellow (new member - name escapes) brought a 20-year-old, 8-inch
Meade LX3 SCT (or possibly a model 2080), which was in serious need of
collimation. The "SAC Optics Team" (Lynn Blackburn, Dave Fredericksen,
and Jimmy Ray, AKA Curly, Moe and Larry, nuk nuk) fiddled with it (!!)
and got it pretty well collimated. Nice images. From what the owner
described, the telescope was in very poor condition when he got it
(after years of storage under bad conditions), and it had to be cleaned
up thoroughly, including the optics. He was pleasantly surprised that
it now works so well.
I tried out my Ronchi eyepiece, and it showed test bands nicely on Sirius.
Rick Tejera brought his little 4-inch collapsable Newt (constructed by
Pierre Schwaar), and re-cemented the secondary mirror.
As always, lots of good discussion, soda pop, and cookies provided by
Paul's wife...
Gene Lucas
(17250)
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