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Re: ATM 32" observing reports, close to the end
This is "music in my eyes". At really good high mountain sky conditions the
Veil reveals in a 20" more beauty and detail, than the mind can catch
already. Next year I will see, how it looks like in a 32", when we hopefully
will have finished our "big one".
Of particular interest for us is the fact, that a 40 mm meniscus is stable
enough. So I suppose, that our 57 mm thick plano concave blank should show
even with a classical type cell no astigmatism too? I think we should
consider your "piano wire" lateral support as well.
I wish you good luck with the tracking system too.
Stathis Kafalis
http://www.geocities.com/dobsonstathis
----- Original Message -----
From: "at making" <atmaking@hotmail.com>
To: <atm@shore.net>; <bigdob@yahoogroups.com>
Sent: Monday, August 19, 2002 10:00 AM
Subject: ATM 32" observing reports, close to the end
>
>
> Hi,
>
> For the first time, I have observed in the 32 with a tuned astatic cell.
A
> friend who know this kind of cell very well tune it in few minutes. I was
> not far but now is good. The difference in the view is simply amazing ! I
> was afraid to have some astigmatism but fortunately there is nothing
visible
> while going from zenith to horizon. The last part to tune is the tracking
> but the first tests are a big promise. It could have been finished but a
> lack of time and our enthusiasm to share time at he eyepiece under a good
> sky as give us problem J
>
> The scope is easy to setup, about 10 minutes. Currently the primary is
> transported in a separate box. The mirror box and rocker or on a trailer.
> The primary and top cage in a station wagon. Two people "drop" the mirror
in
> the cell, remove wheels, put the truss, the cage, baffle system and it's
> ready. First surprise, on 4 setup, twice the scope didn't need to be
> collimate ! and and an other time a small collimation. I know try to
always
> installed the truss at the same place and this way, it does not seem to
> require collimation. May be I will don't need to have the remote
electrical
> collimation system.
>
> The place was a pass in south of france, at 4800 ft. Fun, we decided to go
> at this place at night, so the trip and setup was done during the night.
The
> sky was great naked eye, with a very broad and full of detailed Cygnus
area.
> As for many new scope, we spend first observing session on classical
bright
> object. We were not disappointed to say the least.
>
> M27 was not the classical hourglass shape. It was full of thin details,
and
> extension, only visible on heavy processed CCD images. The extension are
> like an "echo" of the classical shape.
>
> The veil nebula was a AMAZING view ! the central part (between the two
> brightest arc) was like the brightest arc in a 20" ! You have to use high
> quality CCD shot to see as much details and in many case it's more
> impressive at the eyepiece. The broadest part near 52 cygni remember me a
> all the ramifications of rivers are branches of a tree. Complex, hard to
> describe. It was with the paracorr and nagler 20 mm eyepiece.
Unforgettable.
>
> M33, at low power (paracorr +20 mm nag), NGC604 got a distinct shape with
a
> haze around it , and some stars (with good seeing). I will use higher
power
> and try to make some drawing next time as it will be at an even better
dark
> site.
>
> 6543 was great. With good seeing, all classical details were visible.
Green,
> with something like a dark brown/deep red faint line at is perimeter. The
> faint galaxy next to it was easy. Around cat's eye, the haze was visible
and
> something I never notice before, a reinforcement of this haze was visible,
> opposite to the direction of the galaxy if memory serves me.
>
> M13 was big, fully resolved. The faint galaxy between M13 and ngc 6207 was
> easy to see and got a shape.
>
> We also spend time on NGC253, 891, M15, Stephan's quintet,
>
> I can't wait to have the tracking as it full capacity. It should have been
> already finished but when you begin to jump from an object to an other,
it's
> hard to stop 5 minutes J.
>
> Strange things happen, during humid night, the graphite fabric I used to
> cover parts of the cage and focuser board, and in a smaller proportion,
> other parts of the cage are covered with humidity. The truss itself (also
> graphite tubing but made an other way) don't seem to suffer to much of
that
> problem. A good point, this graphite tubing is not cold during cold night
so
> gloves are not necessary like for alu truss. Rigidity of the full
structure
> seems to be excellent. Something I will need to modify a little is the
size
> of the 3 pad that touch the ground, a little wider will be better for
> stability on "unstable" grass place.
>
> Piano wire seems to be good. They are 2 mm in diameter and support a 44
kgs
> (around 97 lbs). Their "free part" are not very long (around 20 mm) but
> seems to be enough. To use the scope as it full capacity, it's good, when
> the collimation is finished, to aim the scope at zenith, move the primary
by
> hand for few millimetres and aim the scope at horizon to let it take is
> position without any stress. Good point to, the meniscus seems to be very
> rigid. I even wondering if it could not have been put on a 18 points ! I
> know that sound an exaggeration but it's not the case. The meniscus is 40
mm
> thick, but seems to have a stiffness close to what can give a 24" 40 mm
> thick, flat shape. I will speak about that with Luc Arnold soon. The shape
> seems to be a real bonus. If I'm not lazy, I might make an even simpler
> cell (astatic with 18 points) one day to see how the glass react.
>
> Sorry for the double mail for people whom are on atm and bigdob.
>
> Frédéric Géa
> http://astrosurf.com/altaz/index_e.htm
>
>
>
>