Shakhbazian Compact Galaxy Groups Observing Notes

    In 1957, Romela Shakhbazian examined a Palomar Sky Atlas plate and noticed a tight group of red objects. She examined more plates and found 16 more such groups and all were about 1’ in diameter, so she wrote a journal article on it. It was thought of at the time as a small tight cluster of red stars. It wasn’t until 15 years later in 1972, when Robinson and Wampler took a closer look and a spectrum of five objects in the first listed group that Shakhbazian looked at and realized that they were not red stars, but galaxies.  They named it Shakhbazian 1 to represent a new system of galaxies called compact clusters of compact galaxies. 

    In 1973, several others took a new systematical search to look for more compact clusters of compact galaxies on the Palomar Sky Survey. The following criterion must be met to be considered for the new system of galaxies:
1.    Consists of 5 to 15 members.
2.    Each galaxy’s apparent magnitude is between 14th to 19th magnitude.
3.    Compact group. Relative distances of member galaxies should be 3/5 of the diameter of a galaxy.
4.    Almost all must be extremely red. No more than two blue galaxies.
5.    Galaxies must be compact. High surface brightness, and not diffuse.
6.    The group must be isolated.

    It turned out that one of the richest groups was the first one, Shakhbazian 1. The spectra of the five objects in Shakhbazian 1 calculated the distance to be about 2 billion light years distant with a diameter of 620,000 light years across and the average diameter of individual galaxies was just 40,000 light years across. In comparison, the Milky Way and Andromeda Galaxy were about 100,000 and 130,000 light years across respectively, and 2.2 million light years from each other. It was also found that the absolute magnitude of the brightest member of Shakhbazian 1 is -23.0, which means that it is one of the brightest known galaxies. The velocity dispersion is very low, suggesting that they are together in one compact group. Imagine what that would look like for the deep sky observer from one of hte member galaxies! 5+ high luminosity galaxies crammed into a "small" 620,000 light year space.

   Then in 1975 Mirzoyan, Miller, and Osterbeck took a closer look at Shakhbazian 123 and determined that it has similar characteristics to Shakhbazian 1. They thought they were onto something. Further research on other Shakhbazian groups showed that the pattern of small velocity dispersion properties was indeterminate.

    After research from 1972 to 1979, it was demonstrated that most Shakhbazian groups are in one of the following types of groups:
1.    Spherical concentrated groups
2.    Chains
3.    Peripheric groups

    Later observations of these groups with high angular resolution revealed that member galaxies are mostly of E and S0 types. This can be helpful for visual observers as it was detectable even at 2 billion light years distant. Also, it has now been shown that the group members are not particularly compact, so the more recent journal articles now call them Shakhbazian Compact Galaxy Groups (Shk).

   By 1979, the catalogue grew to 377 and was compiled by Shakhbazian, Petrosian, Baier, and Tiersch. They produced 10 journal articles. The unfortunate thing was that the coordinates of the groups in the original journal articles given were relatively low accuracy, so more than a few of the Shk groups were difficult to discern in galaxy-rich fields. The good news, almost 20 years later, D. Stoll and team put out ten papers on the photometry and the identification of each member of the groups. I have used his papers to center and mark the members in this observing report. It also turned out that because of the quality of the Palomar plates, some members were faint red stars, not galaxies.
  

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Since this is a very challenging list, here are some observing tips that will enhance your ability to see them:

• A steady sky is key for resolving individual members.
• Take great care when looking. Stars appear brighter in the eyepiece than the stars on the DSS and SDSS images and gives false positives. Examine the provided annotated images and note the locations of the foreground stars.
  
• Keep your eyes dark adapted as fully as possible. Even the sky glow from the sky, especially if the Milky Way is above the horizon, can impact your night vision. When not looking at the eyepiece, waiting for your turn at the eyepiece, or just taking a break, look down at the dark ground, preferably with a hood over your head. I sometimes look down for a few minutes before looking in the eyepiece.
• To further darken the field around you, use a hooded vest.  The hood should block all extraneous light, including the sky glow and even the Milky Way at very dark sites.
• Use your eyepiece guards. They offer an extra light blocking barrier between your eyepiece and your eye.  If your eyepiece doesn’t come with one, you can install one for some eyepiece. Click here for some ideas.
• If you think you saw the object(s), but are not sure, gently tap the telescope or wiggle it.  The stars will wiggle in the eyepiece, and if you saw the object, it would wiggle as well along with the foreground stars.
• If you are tired, you won't see as much. Take a nap or rest. Try to observe in a comfortable position. It helps if you aren't straining your neck (or anything else) when you are trying to observe.  Some fleeting objects would disappear when fatigued.
• Use high magnification, such as 300x or even higher.  When I observe objects from this list, I generally use my 6mm ZAO-II, 5mm BGO, and/or 4mm ZAO-II orthoscopic eyepieces in my 22”. I employ the TMB 1.8x ED Barlow if I need even more magnification.
• Use low-glass count and high transmission eyepieces. Even with modern glass polish and coating technology, there is still a very small, but noticeable difference between high glass count eyepieces, such as the common wide-field eyepiece versus a simple Orthoscopic or Plössl.  Over the years, I’ve done many comparisons between various eyepieces, such as the Naglers, Ethos, Naglers, Pentax XW’s, Orthoscopics (Zeiss, Baader, University Optics, etc.), and Plössl (some makes) and found that low glass count eyepieces consistently outperform high glass count eyepieces.  See Observing Tips, titled Going DEEP with simple eyepieces, for more information.

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This page contains my personal observations of the Shakhbazian Compact Galaxy Groups.

Only galaxies seen are marked.  The numbering scheme used in the images are consistent with D. Stoll's papers.

The idea of this page is to encourage those with large reflectors to give this catalogue a shot. This group is considered the "next" Hickson Groups. All require a large telescope to see the groups. An experienced observer should be able to see what I saw.

Telescopes used:

• 22" f/4 reflector
• 30" f/4.3 reflector
  
• 48" f/4 reflector

When you look through the eyepiece, just imagine what you are really looking at...an isolated distant compact group of galaxies that is not close to any other galaxies.  Not only that, these compact groups contain mostly very luminous galaxies packed in a small space, averaging less than a third the distance between the Milky Way and the Andromeda Galaxy.  Each galaxy is even more luminous than the Andromeda Galaxy.  Just think about it, if we lived in one of the stars in one of those galaxies, there would be several to over 20 very bright naked eye galaxies scattered throughout the sky.

As I observe more Shakhbazian Compact Galaxy Groups, I'll add them here.

Shakhbazian 13

22” @ 328, 383, and 460x – The west member “1” is a faint 2:1 elongated glow with diffuse edges.

A very faint trio of stars, roughly a 45-degree right triangle, are north and to the east. An extremely faint galaxy “9” seen to the east.