The Trifid Nebula – M20
Here’s a shot of the Trifid Nebula – meaning “three lobed”, designation M20. Taken spur-of-the-moment, this is a single 3-minute exposure taken at 6400 ISO. I almost never shoot at 6400, but was looking for instant gratification and figured I’d give it a try. My Canon camera delivered after just a little stretching in an image editor. M20 is 4100 light-years distant at an apparent magnitude of +6.3.
M57 – The Great Ring Nebula
And…another shot of the Ring Nebula. It’s one of my favorite deep sky objects, M57. On this particular night, I’d planed to take many short exposures of M20 to get an improved results. But conditions deteriorated from the forecast and the many high clouds were pretty bad at low elevations and the location of M20. Straight overhead wasn’t too bad and with less atmosphere to deal with, I fixated on M57 instead.
This shot is a combination of nearly 80, 30-second exposures @ ISO 1600. Some were obscured by passing clouds and the transparency was less than expected. But I’m happy with this shot. The Ring Nebula is a relatively small DSO and has an apparent magnitude of +8.8 at 2567 light-years distant. Processed in Siril.
Too dim to see in this shot is a faint, distant S-shaped galaxy. I noticed it when really stretching the image. I was going to name it after myself, but alas – It’s IC-1296. I posted it below. It’s pretty faint at magnitude +15, and about 235 million light-years distant. But you can see it! I never knew it was there.
I’ve been using Astroberry for a while now. Astroberry is an open-source package for telescope automation, and it runs on the Raspberry Pi single-board computer. I have one strapped to the fork-arm of my telescope and have used it mostly for auto-guiding.
Adding an electronic focuser has been a goal for a while now – so I could automate focusing over a period of long exposures, or just remotely control the focus from inside on a cold winter’s night. So, it turns out that Astroberry includes a DIY focus module…you just pick a few I/O pins on the Pi and wire them to an inexpensive stepper motor driver. I used one that cost two bucks, along with a stepper motor salvaged from an old flat-bed scanner. Later, I bought a stepper for $12 (with an appropriate shaft) and a set of small timing belt pulleys for another $12 bucks. A 3D printed motor mount rounded out the hack and allowed me to mechanically-couple the stepper motor to my focus knob.
Initial results are promising! It works – I can adjust the focus remotely from my laptop. A little more refinement of the motor mount should do it. I didn’t write a line of code, and the total cost so far is under $30. Celestron sells an auto-focuser for my CPC-800 scope for about $250. I like mine better. I can make it do what I want from my Astroberry setup. More on this later.