Experiences from "Kellotapuli"

Kellotapuli (bell tower, clock tower) is the nickname for my astrophotography gear shelter, given its looks. It's a variation on the rolling roof shelter with minimal footprint (120cm x 65cm base) where the top half rolls off east. This enables using a steep 30/60 degree roof (convenient when living 60deg north) and a wall-sized door. Many claimed the tower would topple seeing it standing at close to 2.5m tall on a hill, but the looks deceive. It may be 65cm wide at base, but in that direction at the 1.2m level there's also the 3.5 meters of track bolted to bedrock at the far end.

The main design principle was to avoid shoveling snow at winter and this was achieved handsomely. A bit of shoveling is still needed to access the lower compartments where I store the EL-foil for flat fields, but next summer I'll build some additional removable shelving and other fasteners to keep the need for lower comparment access to a minimum. The rails froze over once, that caused a two minute delay opening the box. A reasonable improvement over the "out-house" shelter which necessated shoveling snow for a good hour or more.

The  design was also based on the assumption that this is for astrophotography only, no creature comforts or visual observation conveniences are necessary. There's a small shelf on the north side for a laptop, power and network outlets on the wall, a small ceramic heater keeping dew out during cloudy nights and that's it. The site has a separate, heated cabin for observers, so a remote desktop connection over LAN works wonders. Almost all aspects have been motorized, polar alignment is a bit of an issue with the Synta mounts in fluctuating temperatures. Although it's mounted on a pier the alignment can be off one half a degree if the temperature changes signficantly. This I guess is mostly due to the very long lower altitude bolt contracting at a different rate than the aluminium mount base. Modding the mount base to allow for a shorter lower altitude bolt should solve this problem. The second option for the current mount is to build a completely new alt-az assembly with linear actuators for an automatic polar alignment.

Over all I'm ready to declare the Kellotapuli a success. Now I can head over to the observatory with camera and laptop in my backbag and start exposing the skies in less than 10 minutes from arrival. The slowest bit now is starting the laptop, running the imaging SW and reaching initial focus. From then on the automation could take over should I have written more scripts, but that's worth a separate blog post later on.