Horsehead Nebula - imaging and processing

Dark skies during last Friday's moonless night gave me a chance to work on imaging.  I used my 127mm Explore Scientific APO refractor with the Moonlight focuser, the QHY5III174 monochrome imager, my SSAG guider on the 80mm piggyback scope, all mounted on the Losmandy G11 mount and driven by SkyX Pro via my MacBook running Parallels.  Filters were the Baader LRGB 1.25" set, mounted in a Skyris manual filter wheel.  A previous-night QHY Polemaster polar alignment proved to remain pretty tight.

This is the result of fifty images per color and fifty more for luminance, also incorporating my guide camera through SkyX.  Finished up with 25 images each for Flat, Dark and Bias calibration.

Only 20 second exposures for each science image... I chose 20 seconds due to some issues I've been having with the GHY5III174 monochrome camera reading-out early, before the duration is over, on occasions where I set the exposure length longer than about 30 seconds.  Still troubleshooting that issue.

I found that the guiding plot chart on SkyX showed what I assessed to be too much correction in Declination axis when I checked during the first set of images.  This settled down very well once I decreased the 'Aggressiveness' setting for SkyX guiding.  I did not reshoot the images though, so I know I can improve results in the future.  I will work on improving my guiding optimization next time too, since R.A. guiding looked a bit rough harsh as well.

Processing the approximately 300 images was done via PixInsight.  I'm a newbie on using the software for anything more than a quick histogram correction, but after all day Saturday working through book 'Inside PixInsight' by Warren Keller, I'm figuring out a workflow to integrate, calibrate and correct monochrome images... next time it will be a lot quicker.  I'll write more about that process  later.

Lots more to learn on processing, but I'm ready to call this image presentable.  The size and framing of this image make it difficult to tell what parts of the diffuse glow is from skyglow and what parts are part of the nebula, so I limited my processing so that I don't unnecessarily remove actual detail from the image.

I plan to come back to this target once I fix my camera readout issues so I can get longer exposures and bring more of the color that is clearly visible here.  Thats all for now.

Mark J.