To kick off galaxy season for 2017, I decided to see how well my new ASI1600MM-Cool camera performs on a galaxy I haven’t tried for several seasons. I wasn’t sure it would work very well as the imaging scale is very different from my old DSI IIc and I’m still getting comfortable with LRGB imaging. On top of that I also had some issues with Sequence Generator Pro’s new capabilities for setting the camera gain (these were really probably operator errors!). It defaulted to a gain of zero and I knew about that but had some trouble getting the gain to stick at unity where I wanted it. The other new thing with this image was automatic refocusing every 5 frames or after each filter change. Eventually this hung the session because of guiding issues (the TOAG has trouble when you move off focus, so I need to figure out how to turn off guiding when focusing is happening). As I mentioned, I’ve imaged NGC 2403 before but the last time was 3 years ago (in fact it was “first light” for my PicGoto mount controller—a lot of water has gone under the bridge since then!). My previous images didn’t come close to doing this galaxy justice. This one is better, although the colors could no doubt be improved. The detail in the luminance was everything I hoped for, however. It looks like there are a few additional small faint fuzzies in the field of view (as long as they aren’t just flaws in my optics or processing).

Date: 2-3 Mar 2017

Subject: NGC 2403, spiral galaxy in Camelopardalis

Scope: AT8IN + High Point Scientific coma corrector

Filters: ZWO 31 mm diameter unmounted L, R, G, B

Mount: EQ-6 (EQMOD)+PEC

Guiding: Orion Thin Off-axis Guider (TOAG)+PHD 2.6.2.10 (Win 10 ASCOM)

Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21

Acquisition: Sequence Generator Pro 2.6.0.14

Exposure: 51x300 L, 12x300 R, 18x300 G, 12x300 B

Stacking: Neb 4.1.4, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.327. Aggressively stretched and deconvoluted the luminance. Combined RGB in Neb 4 and stretched and attempted to color balance and correct in StarTools. Layered luminance over RGB in Photoshop CC 2014 and used Carboni’s Astronomy Tools deep space and space noise reduction followed by “less crunchy more fuzzy”, several rounds of layer-masked levels settings to remove some nasty background color cast, topped off with AstroFrame.