Ad Astra Observatory

I deployed the new Gizmo in anger for the first time last night, pot controlling the exposure length, hooked up to the Gemini ST-4 port, hooked up to the Canon, LCD and LED outputs.

It was mostly cloudy last night. It was beyond suckerholes to the “well, I can see it in the telescope, but not naked eye” level of cloud cover across the sky.

I used Vega “near” the horizon for Elevation (it’s a bit far north of the equator, but it was all I could see), and Arcturus “near” meridian (it was well past meridian by the time I got there, but ditto with the seeing).

In short, the Gizmo worked flawlessly. Perfect star trails, perfect bright star at the beginning end, and completely hands-off during an exposure (I went inside and watched TV while trailing).

As advertised, I was off by a little less than a quarter-turn in Elevation (~18′ is what Gemini had been saying). At the point where I left it, I think that I could not detect a drift in 20min. I know that it was at least 10min, but I can’t remember if I did a 20min “just checking” run or not…

Azimuth was close enough that I needed a 20′ exposure to see any drift at all; at 20min, drift was maybe 5 pixels or so (1 px drift in 5min, shooting at ~5”/px, so about 1”/min of drift, 1′ per hour). I left azimuth alone for now.

I have some lovely star trail images sitting on the CF card in the camera that I’ll post soon.

This is the tool I’ve been needing for all these years. Total cost? Less than $50, and about a week of coding. For that, I have a standalone device that can do polar alignment, time lapse photography, and long exposure photography. It can be powered by USB (and also has some minimal Serial logging output), via 9v battery, or can even be plugged into a 12v supply. It only knows how to speak to a Canon DSLR (I can add Nikon support with external hardware), and it only does 2 axes of movement on the ST-4 (not full guiding). As it sits, I think it’s worth at least $249.

And boy does it do the job right. Arduino makes microcontroller development simple and fun.