Design of a fully portable Observatory

The initial rig involved a 114mm diameter Newtonian carried on a Celestron AVX mount. Scope aperture quickly became a limiting factor, as did focuser stability (not designed for heavy weights such as cameras). 

The new Astrotech 8" Ritchey Chretien OTA on the Celestron AVX mount, next to the 114mm Newtonian on a smaller, unpowered mount. 

Not all astronomy gear has to be precision-made. Using a paint bucket lid painted black as a frame, I adapted a 8" Mylar solar filter sheet (and duct tape) to create a sketchy-looking, but effective, solar filter to safely observe and photograph the eclipse before and after totality. 

Used for correcting tracking error the mount encounters as it follows an object across the night sky, guidescopes are essential for sucessful long exposures of celestial objects. With my particular setup, I noticed blurring after anything over 30s in exposure time without a guidescope. As a light-weight and cost effective guidescope package, I chose to use an Orion 50mm guidescope paired with a ZWO ASI-120mm monochrome camera, which uses a CMOS sensor. The guide camera interfaces with a computer via USB and the tracking mount via RS-232. 

There are two main types of digital imaging sensors: CMOS, and CCD. The cheaper and more conventional CMOS sensors, like what's in the Canon T6s, have a disadvantage compared to CCDs for astrophotography: CCDs are much more sensitive to light. So, I chose a imaging system that would run off my portable 12v power pack, yet still deliver top-notch performance. Settling on the SBIG STF-8300, a monochrome CCD with active cooling, I also chose a set of Baader LRGB filters for my electronic 36mm filter wheel. This allows the camera to take a overall "luminence" image with the clear filter for calibration, then take a separate image of blue, red, and green, using each filter to selectively let in that frequency of light. The software can then combine the images into a single color image. 

Looking for a lightweight, low power computer I could run the telescope and cameras with, while also charging the computer off my 12V power pack, I eventually settled on a Microsoft surface pro 4. However, I hit a roadblock almost immediately: the tablet only has 1x USB port, and to control the guidescope, telescope and camera, I needed at least 3 ports...

To improve my I/O situation on my Surface, I decided to modify one of the old surface pro 3 docks. As the dock runs off 12V, I could power all my peripherals and my computer off my battery pack simultaneously. However, I didn't have anywhere to place the bulky dock, which was designed for desk-top use. So, I gutted the electronics from the dock, mounting the main PCB on one of the tripod legs. I also lengthened the cable run from the PCB to the proprietary surface-dock connector to 3m, giving me plenty of room to walk move around the telescope and share the screen with others while still connected to the system. 

 The lead-acid battery pack I had been using was not cutting it. After looking around and being upset with how expensive commercial off-the-shelf battery packs were, I decided to build my own. For this I required batteries, and lots of them. 

Similar to an electric car battery sled, I connected dozens of 18650 lithium ion batteries together to create a large, higher-voltage battery. To do this, I used a kit available from VRUZEND, which enables you to connect the batteries together in a modular fashion without any soldering. This design allows for easy modification of the overall battery, including capacity upgrades and replacement of individual batteries which may go bad over time. 

Using a generic hard-case as the new home for my power bank, I made room for a the battery pack, battery meter, 12v DC converter, 120v AC inverter, and a battery management system. There was even enough room to internally house the batter charger!