Saltwater Witch Micro-Observatory Project

May 29, 2020 - Reading time: 4 minutes

Here’s my situation--and I think this a common one: there is a limited amount of clear night sky--and that’s with or without the moon. I have a limited amount of time to set up all the gear necessary for a night’s imaging run. I don’t have an observatory in my backyard with everything ready to go, mount polar aligned, cameras cooling down, roof or dome rolling back. 

But what if I had something like a self-contained, weather-proof box with just enough room to fit an equatorial mount and a scope? Even if it’s not my main mount and scope, wouldn’t it be nice to have an astro setup ready to go at any time--ready for the next break in the clouds?

That’s where I started with this micro observatory project. My goal is to be able to set up a self-powered astrophotography system that can remain in place through any weather while protecting the equipment, and be operational and ready to image within a few minutes. I don’t need it to be fully automated for now. This is a fairly complicated setup, and so I’m going to take this in steps. The main missing piece of automation is raising and lowering the lid. Of course, all the astro gear is automated, except for a motorized cap, which won’t be necessary without the ability to remotely open and close the lid.

This is what I’m shooting for:

  1. Weather looks clear enough to imaging.
  2. Select a target or two for the night.
  3. Walk out to the micro observatory and unlatch the lid, set it aside, take off the telescope cap, power up everything, move mount from parked position (horizontal) to a home position, weights down and pointed at the NCP. Walk back the house.
  4. Remote into the astro controller (i5 Windows 10 machine) and load an existing sequence or create a new one for the selected targets.
  5. Ready to run!

I started testing this idea a couple years ago with wood frames, and even did some research on wood shipping crates. I settled on this giant water-tight SKB plastic molded shipping container with 27”/68.5cm interior dimensions--it’s a cube. It's made from really sturdy impact resistant and UV stabilized polyethylene (LLDPE), with stainless steel latching hardware.  The stock hinges and straps didn’t work for my purpose--I’ve drilled off the hinges.

Here’s the SKB shipping case I’m using:
SKB R Series 2727-27 Waterproof Utility Case
https://www.skbcases.com/industrial/products/prod-detail.php?d=s18&id=333

I running some temperature and humidity tests right now--it’s very humid and around 86F/30C --so pretty warm. I also had this box out in the yard, closed up and latched all winter long, and temperatures regularly get down (and sometimes stay down) to well below zero F, around -20C. 

So far so good on the temperature--as long as I cover with a reflective cover. My box temp sensor in the box has the humidity well below outside ambient, and the temps are maxing out around 82F/27-28C. That’s warm but destructive, and I wouldn’t be operating the mount at those temps. 

Roll the video...