NGC 474 is an interesting elliptical galaxy.    The spectacular tidal shells and trails surrounding the galaxy have been extensively studied but remain unexplained.   One school of thought is that these tails are the result of a collision with another galaxy.   Another argues that the shells can be explained by a gas-rich galaxy colliding with NGC 474 twice before finally merging.    NGC 474 is also known as Arp 227.   I've been intrigued with Halton Arp's Atlas or Peculiar Galaxies which was originally published at Caltech in 1996.   I'm working my way through a this atlas of colliding galaxies, radio galaxies and dwarf galaxies.   Here is one of the more interesting ones (to me, at least).  

My intention in imaging NGC 474 was to capture as much detail of the tidal shells and trails as possible.   The initial set of LRGB images (4 hours per filter) were captured during the last week of August 2022.   After taking a  look a the integrated image I decided to try to tease out a bit more detail and ran the complete imaging run a second time during  the first week in October 2022.   I added 8 hours of Ha with hunch that more detail could be found.   There was some signal there but not enough to pursue it further.   Perhaps i-prime or r-prime Sloan would yield something of interest.    The additional LRGB images did make a small amount of difference but not as much as I had hoped.  I am pleased that the final image shows some detail of the tidal tails and shell-like structure.   Spiral galaxy NGC 470 is nearby.  

This image is the product of an excellent collaboration with Bray Falls.   In early 2020 we started working together.  Bray is an outstanding Pixinsight expert who helped me come up to speed on a basic working knowledge of Pixinsight.  It became quickly clear that my time was best spent on image capture and optimizing the equipment and software.   Bray would work on post processing using Pixinsight, Photoshop, BXT and other software tools.   I'd add a bit of LightRoom processing from time to time.   I'm really pleased with the results from this collaboration which has only gotten better and better.   

Additional notes:   In mid 2022 at the suggestion of Bob Denny (ACP) image exposure time changed to 300 second exposures using Bin 2.   For several years  600 second exposures unbinned  was standard (for me - for all IMX455 sensor cameras).   This change improved the image capture process significantly.  The C3-61000 uses the Sony IMX455 60mp sensor.   Unbinned,  129 megabyte files cause no end of problems with plate solving.   Moving to 300s at Bin2 improved sensitivity and produced smaller 30 megabyte files which are more easily digested by plate solve software like Visual Pinpoint.    The image capture process is now fully automated in ACP, Visual Pinpoint and ACP Scheduler.    ACP is now configured to plate solve and recenter (and set position angle to 0 degrees)  after every image capture.   The drift on the L-600 mount is consistently measured at less than 2 arc-seconds over this 300s image capture.   No dithering has been used - but worth a look.   Refocusing is done every hour.   In November 2022 a separate guider scope was added reducing the drift even further.   A day or two of mount tuning by the techs at PlaneWave reduced slew settle time to a few seconds and optimized the tracking feedback loop.