Posted in Astrophoto Log on March 20th, 2009 by Northwest Astro
M81/M82
This is a rather late post, but I’ve finally gotten the CGE out for astrophotography. As I am a bit of a glutton for punishment, I figured I’d take this opportunity to make this my first attempt at a galaxy shot as well. So I pointed my setup at M81 and M82 and started taking some 5 minute exposures.
I wasn’t really expecting to actually get an image out of this. I really just wanted to see how good the tracking was on the CGE, and how well it would run while autoguided by PHD. The tracking seems to be holding up just fine, so I am pleased with the performance I am seeing with the CGE. With the LX200 on its fork mount, I was having frustrations keeping the guiding running well beyond 2 minutes or so, while this gave 5 minute subs no sweat.
Now, that isn’t to say there aren’t things I’ve learned this time out:
- I think the filter I used impacted the brightness, and I didn’t take long enough exposures to really get the detail I could have gotten here.
- I did figure out how to user layer masking to restore M82’s core after stretching to make M81 visible, which led to a fair amount of preserved detail there.
- Noise is probably gonna kill me if I keep shooting galaxies like this with not enough exposure. You can see a fair amount of noise creep into M81 on the right, and really if I need to take longer exposures, the DSLR I am using will start becoming the weak link. Dark frames will help less and less, and more noise will be even more visible with longer exposures, and it will be even harder to get more exposures to balance that out. And it will require even longer exposures to get the signal above the higher-level noise.
Although for now, enjoy.
