Ad Astra Observatory

As a test run before the Golden State Star Party this year, the family and I are going camping for the weekend at Coyote Lake. I haven’t been camping in quite some time, and in particular, it’s been about 5 years (and 3 mounts, two cameras, and several OTAs ago) since my astronomy rig had to go without a steady supply of 110v AC power.

I bought a deep cycle marine battery last year, once I figured out that my powertanks were dead from disuse (see “Clear Lake” around July of last year). I wired up the battery to drive everything, but I never really got a chance to test it while up in WA last August (a lot of rain, plus I got wrapped around the axle with the whole RCC thing). So the battery sat around unused for most of the year.

About a week ago, I pulled out the battery, charged it up, and started testing unplugged in the backyard. I learned some things.

First, there’s no point it putting the mount on a tripod unless you have to; it just adds an unnecessary variable to an already complicated setup. I made sure the tripod worked and that I could tear down in a hurry if I needed to, then put the mount back on the pier.

I learned early that the battery had no problem whatsoever running the mount, camera, and USB hub all night long. However, whenever I plugged in the computer, things went haywire. So I left the computer on house power and just drove the mount for an evening. The mount had insanely good tracking that night; RMS error was around 0.25″ (yes, one quarter of one arcsecond, 250 milliarcseconds (: ).

I tested a variety of things to determine why the computer wasn’t working; I am still not 100% sure why it failed, but I decided to do two things to remedy the situation:
1) I bought a second deep cycle battery (identical to the first one), and wired it in parallel (+ to +, – to -, for same volts and twice the amps).
2) I replaced the 100w inverter with a 750w inverter.

In short, that worked. Hooking up the computer directly via 12v, everything was fine until the computer had to do a lot of work at once (I plugged in the USB hub and it wigged out while loading drivers). Against my better judgement, I switched it to run off of the inverter, and it worked great. The inverter’s fan didn’t even start up. In fact, it worked so well that I briefly considered just running everything (including the mount) off the inverter. I left the mount and dew controller running off of the battery, with the computer, USB hub, and camera running off of the inverter.

That rig ran all night and when I woke up, the battery charger said the battery bank was at 75%, 12.5v. Nice. I can probably do a 3-day weekend without having to charge.

So I spent the evening packing things up for the trip (of course it’s clear as a bell out tonight). Mount went into 3 containers (head, tripod, and accessories). Cameras into another. Data and power cables into a third. And so on. I’m taking Cassie and Pumpkin with me, leaving Veronica and Trixie behind.

I’ll gather what data I can this weekend, both through the scope and about the rig as it runs au naturel.

… and maybe I’ll have a worklist to get through before heading to GSSP.