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I've never been a big galaxy imager. Galaxy season only spelled the end of nebula season for me. Andromeda, M81 and M82 and the Leo Triplet is about it. However, this year, my interest in imaging galaxies has come alive. I decided to break out my old C8 this year and put to use. I invested in a corrector, electronic focuser, dew shield etc. So I've got it collimated and dialed in ready for galaxies. What are some of the tips and tricks for imaging galaxies have you picked up over the years? There are some great images here on AB. As an example: I see many of the subs are much shorter that the typical times for nebula so as not to blow out the core. Pretty easy. Not to get into processing but that is another difference than nebulas but there are plenty of YouTube videos for that. So, I want to have a successful season of a couple of good galaxy images this spring. I've already started with NGC 4565 as it's favorable in the sky right now. I adjusted my sub times from the typical 300 seconds to 120 and so far so good. I'm going to stretch this aquisition over several nights. Like always, the more integration time the better. I found Andromeda fairly easy. But these smaller galaxies using longer focal lengths is tougher. Help me out here with your experience  Using a Celestron C8 with a Starizona Corrector/Reducer so about 1450mm of focal length. A C11 would probably be better but I'm using what I have. Though I know not as ideal as a monochrome camera, I'm using my ASI294MC Pro with an Optolong L-Pro filter. Everything mounted on a GEM45 in an observatory in my backyard under Bortle 5 skies. PS. I have access to a friend's C11 but I know I would need good to excellent viewing for that scope. Fair skies would translate to over sampling with the 294, right? Mike |
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You're unlikely to blow the core of galaxies, other than the couple of brightest ones if you shoot at high gain and long exposures so i would not bother lowering your typical exposure times for galaxies alone. M31 is a problem, but not many other galaxies have an issue with the core. If you have a nicely working setup and wind is not too big of an issue then there wouldnt be any real difference between 2 and 5 minutes per sub, at least as far as sharpness is concerned. So shoot however long you are comfortable with already. Avoid nights with high cloud as that can really mess up the stack, even if it doesnt look too bad at a glance. For smaller galaxies we are at the mercy of our seeing, at least with your fairly large aperture scopes mentioned here. You do need to check that everything is as well collimated and stable as possible to have the best fighting chance. Aim for a long integration for dim and smaller galaxies to get decent signal to noise ratio. That way you give deconvolution a better set of data to work with. If you dont have BlurXterminator, then get it. It really shines with galaxy images. |
