NGC 5660 is a type SBc (barred spiral) galaxy in the constellation Boötes.  Its visual magnitude is 11.9, but I found it to have low surface brightness outside of the core.  It has a faint companion that may or may not be interacting with it.  I was not able to find much information about this rarely imaged galaxy.  I also did not detect any hint of a bar, but one can only expect so much detail when imaging tiny galaxies with a 4” refractor.  If this galaxy was much closer and larger, I think it would be a very popular imaging target.

This image is part of a widefield galaxy project I started back in early March with the Esprit 100ED and QHY268M.  The field of view is enormous compared to what I can achieve with my C11 EdgeHD, allowing three or four interesting galaxies to be imaged at the same time.  When the seeing is poor, it makes more sense to use the refractor to get multiple targets into one field of view.  The seeing was poor on two of the nights with some wind interfering, so I think it was a good decision to use the refractor.  The C11 is itching to go outside next month, though.

The luminance subs were 300 s in length, and I used Mode 3 (Extended Fullwell 2CMS), Gain 14, Offset 15 for image transfer.  I am liking Mode 3 a lot so far due to its deep wells, which permit longer subs to be taken without “cooking” the stars.  The RGB subs were 240 s in length, and they were shot with Mode 1, Gain 56, Offset 10.  The luminance channel is a synthetic channel created by stacking 180 of the available frames using median combination.  I was able to obtain sharper details in this galaxy and the other small galaxies in the field of view by using 90% of the available LRGB frames and tossing those with the highest FWHM.

Since the native image scale of 1.4” per pixel is a little too chunky for tiny galaxies, I applied 2x drizzle during stacking to achieve a more reasonable 0.7” per pixel.  The resulting image files are huge, and processing them in multiple-layer format is enough to set my computer’s GPU on fire.  Also, the spacing between the targets is wide enough that it would require the viewer to zoom in to full resolution to appreciate the different DSOs.  I therefore will be posting separate images of the objects in this field of view that are cropped to frame the targets well.