This is Hickson Compact Group 40, or HCG 40:

A Hickson Compact Group is a grouping of galaxies that are relatively isolated, meaning that they are not part of a larger system, and are in close physical proximity to one another.

This grouping is made up of five members; I have labeled each in this image:

I find these groupings interesting because when I learned about galaxies I thought them as large and isolated, yet HCGs are often so close to one another that they are actually interacting. In this image, it appears that members E, C, and B might be interacting.

The most famous HCG is HCG 92, or Stephan’s Quintet.

Near member D is another PGC galaxy, but it is not part of the grouping because it is either a foreground or background galaxy. There’s also a galaxy near member B which is on the star chart but not visible in this image, which is also not a member of the grouping.

Acquisition and Processing

I took this image using Slooh.com’s Chile Two telescope. It’s made up of five missions, two of which were multi-luminance missions. So, the total exposures were as follows:

  • Luminance: 8 exposures at 50 sec binned 2×2
  • Red: 2 exposures at 20 sec binned 3×3
  • Green: 2 exposures at 20 sec binned 3×3
  • Blue: 2 exposures at 20 sec binned 3×3

I processed this image using PixInsight. I tried MaxIM DL first, but the galaxies were not resolved very well using it. I was able to achieve much more detail with PixInsight. The colors are also more vibrant in the PixInsight version. I did some minor noise reduction in Photoshop because I needed more exposure time on target, so I made up for it using noise reduction.