Abell 1656, the Coma Galaxy Cluster (Álvaro Méndez)

Abell 1656, the Coma Galaxy Cluster

A splendid cluster located 320 million light years away full of ellipitcal and lenticular galaxies. Quasar QSO [HB89] 1256+280, about 11 billion light years away, can be seen.

I'm not sure if it is me, but I think I notice a gravitational lens effect around the two giant galaxies NGC 4874 and NGC 4889. This is something I haven't seen in other photographs of this same cluster, although it is clearly evident in Hubble's Abell 370 or 2744. The way I stretched the image on my second attempt with GHS kind of revealed this effect, as well as the HII regions all around the photograph, which, although subtle, make their presence seen. Also I was hyper-strict with the subframe selection and discarded more than a half, leaving only the best 5 hours. Looking forward to adding more data next time I can to boost detail and signal. Also, I used my particular method for noise reduction that I always use with nebula, but for galaxies this time because I didn't want the luminance to be blurred with conventional denoising methods. It is a reprocessing after color treatment adding back the unsaturated luminance and creating an LRGB, similar to the mono workflow.

On a curious note, after publishing the first version and resting my sight I realized the picture had bad gradients. I decided to recalibrate it and do a new set of flats. I think the previous ones were overexposed. Then proceeded on to a new stretch, this time with the Generalized Hyperbolic method.
Lesson learnt, I thought now with Graxpert I was cooking with gas but it does not replace properly exposed flat frames! Now I think it looks better, altough I never like how I process dark regions of space (also maybe it has something to do with using OSC cameras, there's so much noise, but... I live in a cloudy/rainy area North of Spain and observing time is limited.)

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Title: QUASAR QSO [HB89] 1256+280 ANNOTATED

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Abell 1656, the Coma Galaxy Cluster

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