Galaxy cluster busting

Lake Sonoma Observations 5/31 and 6/1

by Jane Houston Jones

My ongoing project, for when I feel the need for a project, is to observe the various lists of galaxy clusters and galaxy chains. So when I have a nice transparant sky and am feeling particularly focused, these are the projects I like to work on.

These spring nights have been perfect for observing some of these clusters and galaxy chains and this weekend I was able to check off a few more of them.

I use my 17.5-inch f/4.5 Litebox reflector for these projects, and use one eyepiece exclusively, my old workhorse 9mm Nagler which yields a 222x magnification and a 22 minute field of view. To help my starhopping, I also use an 80mm Orion short-tube refractor as a finder scope attached to a 25mm eyepiece which used to have a crosshair, but it broke off a while ago.

Following the advice Ray Cash gives on his deep sky webpage, I made a Hickson/Abell cluster binder a couple years ago, where I have a section for each of these objects. I have some printed finder charts with a telrad bullseye superimposed and made other charts with a 9 Nagler field, and I included an image of each object with the other information in the binder. I also write my observing notes right in the notbook so it becomes a permanent record of my project. It also makes great reading on rainy nights!

If I can't find them, well, I have alot of fun looking for them, and have the paper for backup and for reminiscing later. Even a red flashlight dimmed down as low as it can go is often too bright, so I usually just try a couple of these on any given night, try to memorize the fields and try not to use flashlights, and set up as far from the "brighter" people as I politely can

This weekend at Lake Sonoma, I worked in a little patch of sky around Corona Borealis and Bootes, which yielded many of these gems.

Hickson 69 was my first target in Bootes. Ra/dec 13h 55m +25 04. With averted vision and patience I coaxed a somewhat distinguishable trio-like texture here. I could imagine 3/4 clumps. These are in the mag. 14-15 range.

Hickson 71 was next in Bootes. Ra/dec 14h 10 +35 30'. Brighter than than mag.14 I could see two clumps, "A" being the largest, a face-on galaxy. These are IC4381 and 4382 and there are some others that I didn't see, and they don't have a number.

Hickson 72 also contains mag 13.9 Arp328 in Bootes. Ra/dec 13h47m +19 05'. Galaxies in 14.8 to 15 range. Now this galaxy cluster was near a brighter mag 13.5 star, sort of a wormlike streak.

Hickson 73 also contains mag 13.2 Arp 42, NGC5829. Ra/Dec 15h 03m + 23 20' , and I could only spot the one galaxy here.

Also in Bootes, NGC5544, 5545 and 5557 are a nice trio near Arcturus at Ra/dec 14h 17 +36 34'. 5557 is the brightest at mag 11, and all three fit in the field of view at 125x with a 16 Nagler. They barely squeeze into the 9 Naglerview.

NGC5895, 5896, 5893 are a nice mag.15 trio next to NGC5900 and 5899.

NGC5929 and 5930 are a tiny interacting M51 wannabe in Bootes! At mag. 13.6 and 12.2, they are well within the capabilities of medium aperture telescopes. Ra/dec 15h 26.1m +41 40'

NGC5990, 5888, 5886 at Ra/dec 15h 11 +41 30' are a triangle of faint smudges, the brightest being magnitude 14.2

NGC 5754 (mag 13.9) is brightest member of a little group with NGC 5754, 5753 and 5752 at Ra/dec 14h 45m +38 46m

I was testing my personal magnitude threshhold to get a sense if I could try for the Corona Borealis cluster, Abell 2065, which is over one billion light-years away, and contains over 500 galaxies. There are not very many reports of observations on this cluster. The brightest of these is around 17th magnitude. I used the Millennium Star Atlas page 646, Ra/dec 15h 22.29 +27 and I thought I detected some smudge-like apparitions both nights, with averted vision that gave me a headache! I spent over an hour on this tiny field both Friday and Saturday night, and was certain of my star field, compared images and sketches (NSOG 2-113) which I had printed out and memorized. There is a pretty pair of yellow mag. 7 stars, Struve 1932 nearby.

A little easier was Seyfert's Sextet in Corona Borealis, This is Hickson 79, and the brightest two of the objects in this compact galaxy group are mag. 13, and the dimmest are 16.5. My friend Bill Cherrington has seen seven galaxies in this sextet, probably through his 25-incher, and he is correct, 79b is actually two objects. I could resolve the three brightest members at 222x with my 9 Nagler cluster buster, and the 6 Radian (333x ) just didn't help any. A better night will help. Maybe a night wil Bill's 25 incher will help more!

One more Hickson galaxy, actually quite dim, but one I have been able to show others at the eyepiece is Hickson 55 in Draco. This is a group of five galaxies aligned like peas in a pod, and that is exactly what it looks like. It is fun to show people NGC 3735, a nice "bright" mag. 11.8 galaxy nearby, and then guide them to the peapod chain, which is actually visible to guests at the eyepiece, sometimes. Ra/dec 11h 36.0m +70 32'

I also showed Eric (with young son) many cool objects such as M104 and especially the nearby asterisms, the Star Trek triangle, and the arrow asterism which points right to M104. They liked those as much as the sombrero galaxy. I performed a collimation on our Sidewalk Astronomers loaner scope, up at Lake Sonoma for its second night in a row! How's that for enthusiasm by its adopted family! And an Army Corps of Engineers ranger stopped by, was bored with making his rounds and seem interested in some views, so I switched gears from the faint fuzzies to show him examples of each type of object and do a little astro PR at the same time. He walked around without flashlight, which I thought was nice, and I invited him and his 7 year-old son to the Sonoma Young Astronomers meeting next Friday when I'll be making comets with dry ice, dirt and some organic materials.

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