The 1 billion light-year club

With any number attached to light-years we lose all sense of human proportion, but there's something magical to me about the 1 billion l.y. mark (maybe listening to Carl Sagan had something to do with that!). At GSSP, I spent some time each night soaking up some 1 billion year old photons from a variety of galaxies and savoring some ancient light with my 18-inch Starmaster.
 
IC 1101 is a supergiant elliptical that dominates Abell Galaxy Cluster (AGC) 2029, located on the Virgo-Serpens border at a distance of 1 billion light years (z = .078). This galaxy is one of the largest known in the universe, with a huge halo extending from 4-6 million light years in diameter. To give that some perspective, the Andromeda galaxy lies a mere 2.5 million light years from the Milky Way.
 
At 280x, it appeared very faint, very small, slightly elongated ~N-S, ~15"x10" and was visible continuously with averted vision. The galaxy is squeezed between a mag 14.7 star 27" E and a mag 15-15.5 star 47" WNW, just slightly south of a line connecting the two stars. No other members of the cluster were seen. I also viewed this galaxy at a similar magnification in Alan Agrawal's 24" f/3.3 and logged it as "faint, very small, round, oval 3:2 N-S, ~20"x14". Could just hold steadily with direct vision."
 
Interestingly, IC 1101 was discovered visually by the 19 year old son (Edward) of comet-hunter Lewis Swift on June 19 1890 using Lewis' 16" Clark refractor as they searched for new deep sky objects. Lewis noted that he and Edward disagreed on the description after the telescope was moved, so there was no published description. If anyone is interested in tracking it down, the coordinates are 15 10.9 +05 45.
 
The Corona Borealis Galaxy Cluster (AGC 2065) is the best known galaxy cluster at the 1 billion light year mark. A few months earlier at Fort Davis, Texas I viewed dozens of cluster members in one eyepiece field using Jimi Lowrey's 48-inch behemoth. In my 18-inch scope, though, I've only seen a half-dozen members. AGC 2065 is part of a huge Supercluster that includes AGCs 2056, 2061, 2065, 2067, 2089 and more – all at roughly 1 billion l.y distance.
 
At GSSP, I took a look at AGC 2061 and picked up three of the cluster members that are also in the 1 billion light year club. This cluster is located just a half-degree northwest of 5th magnitude Eta CrB. The brightest of the trio was 15th magnitude PGC 54787 (CGCG 165-41), a faint, small glow elongated 3:2 SW-NE, 20"x14", with a low even surface brightness. It was easy to locate using the double star STF1935, a striking equal pair of mag 10 stars at 9" separation. Nearby were PGC 54777 and PGC 54819, both 16th magnitude knots. Within AGC 2069, PGC 54997 (CGCG 165-51) was a relatively easy find, although there was no structure – just a very faint and round, 15" glow.
 
On the last night, a group of us used Alan's 24" and Paul Alsing's 25" to view Hickson (HCG) 50, the most challenging target of the 100 Hickson Compact Groups. Paul pulled out a finder chart, which made it a snap to star hop over from M97 (just 20' away). Although the individual 5 members are 18th magnitude or fainter, the combined glow was detectable as a small, dim patch. Perhaps not an exciting sight, but fun to consider that HCG 50 resides at a whopping 1.8 billion light years!

Steve Gottlieb

-- 
TAC on Meetup: http://www.meetup.com/SF-Bay-TAC/
CalStar 2011: http://www.sjaa.net/CalStar
Subscribe/leave this list: http://observers.org/mailman/listinfo/tac