My name is Juan. I live in Gatineau, Quebec. And I have an small observatory 100 Km North of Ottawa.
This page is mainly dedicated to Astronomy under extreme cold. Mel Bartels telescope control system.
And other bits and ends.
Nov. 10, 2007
Last fall I embarked on Mel Bartels
telescope drive adventure.
It consist in a sophisticated stepper motor control program. That can convert any telescope into an accurate GOTO instrument.
Given the rigors of Canadian winters and the fact that the scope sits in an unheated observatory 100Km from home. I had planned on assembling the project at a leisurely pace at home during the winter months. And then. Installing the system on the German mount at the observatory come spring time. There was no way that I was going to be caught tapping screw holes on metal in sub zero temperatures !...
Getting there is half the fun !This has been a very mild winter. But as luck would have it. A cold snap decided to bring the temperatures down to -30C on Friday and -35C on Saturday ! The observatory is on top of a hill, at the end of a 1000 foot trail through the woods. Normally. Transporting all the equipment ( 2 desktop PCs, monitors, tools, etc.) would have been easy with the help of my small four-wheeler. But due to the extreme cold. I could not get the darned thing started. So I had to snow-shoe all the equipment up to the observatory by pack sac.
! What are we
The installation actually went quite well ( I did not loose too many fingers). The only accident occurred when one of the Plexiglas boxes that I had built to cover the gearing mechanism. Fell off the edge of a chair. The face plate shattered as if it was made out of glass. Plexiglas don't flex too much at -30C.
While setting up the connections for the ST-4. I placed a mini screw driver between my lips...
INSTANT SEAL!!! I'm sure I won't repeat that one again... this winter!
(picture not available)
Last summer. I installed a quality sound system with home made speakers (my other hobby). Suddenly seeing took a beat. All stars had become pulsars. The low frequency sound waves were making resonate the large sonotube scope. You can actually stick your head in the scope and hear the base get amplified, some frequencies worst than others.
Sliding weights on both the opening and closing wires are a must
in order to always maintain wire tension for smooth winch operation.
Why I don't suffer from differential flexure
The guide scope mount is made of oak and is extremely rigid in all axis.
My design philosophy was simple.
Not only should the guider mount not depend on the main tube for strength.
But it should actually add strength to the main tube.
A good focuser mounting platform will not only reduce flexure.
But will also allow for easy critical adjustment of the focuser in all axis.
And as in my case. Solve vigneting problems.( The hole through the platform and the scope tube is now 3.5" diam).
Four aluminum straps tensed and bolted around the main tube. Provide further antiflexsure support. One at the mirror cell. Two at the scope cradle / guider mount intersections. And one at the spider mount. The later allows to tense the spider vanes at levels that would otherwise deform the tube into an square.
The above shot of M13 was taken with Mel Bartels free telescope control program. As you can see. It is capable of very accurate tracking. But what is really fun is to click at an object on my PC planetarium and see the big telescope majestically slew to it with pin point accuracy.
(for those that accuse cardboard tubes of flexure)
(click to enlarge)