Pommier Observatory
Submitted by Chelsea Chin
Pommier Observatory: 10’6′ Ash Dome
“This is the new Pommier Observatory. It consists of a 10’6” diameter Ash Dome on a supporting structure building. I absolutely love this new dome. It is the real thing!
It has independent upper and lower shutters. The lower shutter covers the sky from the horizon up to 30 degrees above the horizon and I will rarely image things in that part of the sky. Therefore, I can leave the lower shutter closed and it greatly reduces stray ambient light in the dome. The shutter motors are quiet and the dome rotation motor is very quiet.
The door is below the dome and I can enter and leave as often as I want without interrupting imaging. The dome electronics keep the dome slot centered on the telescope’s position and updates every few seconds, so it tracks my targets across the sky flawlessly.
An enormous advantage of a dome observatory compared to a roll-off roof observatory is protection from the wind. Wind will not enter the dome through the dome slot, simply because it has no exit. So the telescope remains rock steady for imaging even on the windiest of nights. Wind can still hit a telescope in a roll-off roof observatory and shake it, leading to jiggly stars. Also, wind hits a flat wall of a roll-off roof observatory and creates turbulence that spills over the telescope, degrading seeing conditions. In contrast, wind will flow smoothly around the curved surfaces of a dome observatory maintaining better seeing conditions.”
Rod Pommier – Pommier Observatory | Portland, Oregon USA