Birch Mesa Observatory

Newly Updated 9/3/01

Nestled in the pines at an elevation over 5100 feet near Payson Arizona, the authors Birch Mesa Observatory contains a suite of astrophotographic instruments used to photograph the sky on every available night during dark of the moon each month. The primary instrument is a homemade 12.5" f/5 Newtonian with coma corrector optics on a remachined Astrophysics 1200 QMD mounting for precise tracking. Auxiliary instruments include 8" and 5.5" schmidt cameras, Super Taukamar Pentax wide angle lenses, a 6" f/3.6 schmidt Newtonian and 80mm f/4 Vixen refractor for a super finder for CCD work.


(Click on the image for a larger view)

Outside view with new green color scheme to match house. On the left, the south end, the Omega Centauri wall is folded down to allow unobstructed southern viewing.

Close up of the roof rolled off, showing smoked lexan windows and galvanized steel roofing to shed snow.

Inside view of the roll off roof, showing frame structure and wheels.

Roll off roof closed, normal storage position. This is how the 8x10' structure looks in my back yard when the scope is stowed, and the sky is cloudy. The top section is a frame work made up of 1x3's with sides of smoke lexan sheet gables. The roof itself is a standard galvanized steel roof, to make the 2 to 4 feet of snow slide off easily in the winter. (65K)

Roof closed, south wall. Here we see the "Omega Centauri" wall, that folds down for low horizon access. This enables me to see the famous globular in a clear low southern sky, just skirting the top of the pine trees. (63k)

Roof rolled off, eastern side. Here we see the lexan and tin roof rolled to the north, and although the scope is folded down, the single sided truss allows good access to the northern sky as well. (66k)

The Telescope

Overall view of the interior, looking from the south into the folded down Omega Centauri wall. The scope is built extensively for astrophotography, with an emphesis on light baffling and thermal cooling considerations.

The business end of the 12.5" f/5. The ST7E is seen attached here, with all of its cables and water cooling hoses. An 8x50mm finder, and JMI DXF2 focused are key elements.

The mounting started out as a Astrophysics 1200 QMD mount, but because of extensive design problems, I had to remachine the drive section to get satisfactory tracking performance.

80mm f/4 Vixen refractor is used to center CCD subjects on the chip, in addition to JMI Max digital setting circles.

One of the most severe problems with the mount was stepper motor vibration. The fix seen here introduces a damping coupler between the motor and the worm gear.

Looking down into the end of the tube you can see my fiberglass secondary support, and the cooling holes covered with black cloth.

Interior Features

Water tub with submersible fountain pump used to drive the 3/8 vinyl hose into the camera for cooling. As long as the water is 75 degrees or cooler, the action will be very effective.

Desk for Laptop computer to control the telescope and do CCD imaging.

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