Markarian's Chain of Galaxies
Part of a Galaxy Cluster in Virgo
RA: 12h 27m 34s; Dec: 13° 16′ 35″; Dist: ~54 mly
Cygnus Loop Supernova Remnant
I shot the data for this object at the Texas Star Party, 2016 and 2017.
At the star party in 2016, my camera quit working. QSI was kind enough to
lend me another and I was actually able to still get 4 nights of imaging.
Total Image Frames 321
Total Image Time 14 hours 40 minutes
Camera Filter Frames Exposure Elapsed Time Start Date End Date
QSI-683 Lum 24 180 sec 1h 12m 1-May-2016 1-May-2016
QSI-640 Lum 43 240 sec 2h 52m 4-May-2016 7-May-2016
QSI_683 Lum 94 90 sec 2h 21m 21-May-2017 27-May-2017
QSI-683 Red 10 300 sec 50m 1-May-2016 1-May-2016
QSI-640 Red 15 360 sec 1h 30m 4-May-2016 7-May-2016
QSI-683 Red 29 180 sec 1h 27m 21-May-2017 27-May-2017
QSI-683 Green 10 180 sec 30m 1-May-2016 1-May-2016
QSI-640 Green 15 360 sec 1h 30m 4-May-2016 7-May-2016
QSI-683 Green 27 180 sec 1h 21m 21-May-2017 27-May-2017
QSI-683 Blue 10 150 sec 25m 1-May-2016 1-May-2016
QSI-640 Blue 15 300 sec 1h 15m 4-May-2016 7-May-2016
QSI-683 Blue 29 180 sec 1h 27m 21-May-2017 27-May-2017
Imaging Locations Fort Davis, TX - Texas Star Party
Imaging Instrument 4 Inch Refractor at Prime Focus
Focal Length 530 mm
Focal Ratio 5.0
Imaging Camera QSI 683ws-g and QSI-640ws
Guiding Instrument OAG via QSI IGP
Guiding Camera Starlight Xpress Lodestar X2
Image Capture Sequence Generator Pro
Guiding PHD v2
Image Processing PixInsight
Other Image Sizes
Full Resolution Image - email me
Half Resolution Image (3325x1662)
Medium Image (1200x600)
Small Image (600x300)

Imaging Notes
This was challenging as I had 5 sets of data from 2 cameras. Each set was rotated differently and the two cameras were very different in shape and resolution. PixInsight handled the registration and scaling very well.
The difference in rotation, however, resulted in sections of the image that had good SNR (lots of frames overlapping) and sections of low SNR (not as many frames overlapping). That made processing a lot harder. I had to do the wide crop to eliminate as much of the low SNR region as I could. You can still see lower SNR remnants in the image, especially the upper right corner.
The background also suffered and was not very smooth. Aggressive noise reduction, a tightly controlled non-linear stretch, and a little bit of de-saturation cleaned it up somewhat.
It's amazing how many galaxies are in this shot. PixInsight found 217 within the bounds of the image. There are a couple places that it doesn't look like I went deep enough to get the label's galaxy, but most of them do show up.

Objects in the Markarian Chain
Annotated Image

Channel Images
Inverted Luminance
Inverted Luminance