The TARDIS micro-observatory is now in operation; hopefully we’ll start to see a few more cloudless nights and I’ll be able to capture some new data. In the meantime, a brief write-up of the construction.
The idea started with a need to cut down my nightly setup and teardown time. Not having a permanent observatory, setting up my imaging rig each night could easily consume as much as an hour, between carrying all of the gear into my back yard, assembly and, worst of all polar alignment (since polar alignment requires darkness, time spent on this takes away directly from imaging time).
The first big step in reducing this setup time was to eliminate the need to polar align each night. To achieve this, I constructed a permanent concrete pier on which to sit the mount head, such that I can do a mount alignment once and then leave the mount head outside, covered up, for several weeks or months. The rest of the assembly comes indoors when not in use.
To start with, I just used a metalized plastic bag as a cover for the mount, but I wanted something more permanent; hence the micro-observatory concept.
The micro-observatory is a rigid cover that is just big enough to cover the pier and mount head. One side is a removable door, allowing the rest of the assembly to be wheeled away. By having the rigid cover, I get a little more permanence, plus a space containing trapped air which reduces the likelihood of dew forming on the mount (especially with an incandescent light bulb which will be installed at some point).
Some images showing the construction are shown below. To keep the weight down, most of the construction is based around a frame built from 2x2s (assembled using 3″ construction screws) with the side panels filled in with lightweight 1/4″ plywood panels. The roof and some additional cladding (covering almost all of the 2x2s, leaving very little of them exposed) are all constructed from 1/2″ birch plywood.
The roof is by far the most awkward part of the construction. Not shown in the diagrams are the blocks underneath each of the diagonal joins that the roof sections are screwed to in order to make the joins a little stronger…
The next part of my strategy for reducing setup time is my portable electronics box, but I’ll leave that for a future post.
Update: I took a new picture of the TARDIS today (June 19th) from the same spot as the old one, just to show how much the garden has changed since the earlier picture was taken in April.