OR: GSSP

Stretching across 35 degrees of western Hercules is an immense river
of distant galaxies (redshift z = .034 translates into roughly 450
million light years) that connects the Hercules Supercluster (Abell
Galaxy Clusters (AGC) 2151, 2152 and 2147) with another rich
supercluster containing AGC 2197 and 2199. These galaxies are
roughly twice the distance as the Perseus-Pisces Supercluster and
more challenging to view, so I usually attempt to chase down members
with my 18" Starmaster on nights of excellent transparency.

Although we still had the affect of some smoke from the wild fires on
Friday night at GSSP, conditions were certainly good enough to dive
into the southern end of the extended Hercules supercluster where it
dips into Serpens and ends near the rich cluster AGC 2052. This
Abell cluster contains no NGC members, so was missed by the Herschels
and other 19th century visual observers with larger scopes. UGC 9799
(15 16.7 +07 01), a giant cD galaxy, sits in the center of the
cluster and has likely cannibalized a few neighboring galaxies that
have wandered too close. At 280x, UGC 9799 appeared fairly faint,
moderately large, elongated 3:2 SW-NE, ~0.9'x0.6', broadly
concentrated. A number of faint galaxies are huddled nearby
including CGCG 49-89 1.1' S, PGC 54521 0.8' W, CGCG 49-91 2' N, CGCG
49-92 5.5' SSE, PGC 54554 8' SE and many more. It was a lot of fun
tracking these down and 15 members were logged within 30' down to mag
16.4(B).

The best night at GSSP was still to come, though. Although it looked
nearly certain we were going be skunked by clouds on Saturday night,
conditions miraculously improved at the last minute and this turned
out to be a perfect opportunity to chase after even fainter nasties.
AGC 2256 is located in Ursa Minor, 1.7 degrees northeast of NGC 6217,
the brightest galaxy in the constellation NGC 6217. At a redshift of
z = .058 this cluster resides a whopping 800 million light years
away. The barred spiral NGC 6217 was the perfect place to begin the
hunt as it was showing off quite a bit of spiral structure (recorded
earlier) --

NGC 6217 (16 32.7 +78 12). Fairly bright, fairly large, elongated
2:1 NW-SE, ~2.5'x1.5', small bright core. Contains a bright stellar
nucleus or a star is superimposed at the center of the core. At the
NW end a faint spiral arm is attached to the main body, winding north
and then trailing back nearly halfway along the NE flank. With
concentration a dark gap is visible between the arm and the main body
(bar) of the galaxy. A very short extension is strongly suggested at
the SE end, bending towards the west.

I moved over to AGC 2256 (17 03.7 +78 43) and Mark Wagner and I
started to pick apart the cluster. Unfortunately, as Mark mentioned
in an earlier report, my printed Megastar chart was not going deep
enough and we started noticing ghostly patches that were popping out
of the black background with averted vision. Mark fired up his
laptop, turned on the dimmer galaxies in Megastar and we went to work
again. The brightest 3 members of the clusters are NGC 6331, UGC
10726 and MCG +13-12-017 with many of the members arranged in a
chain. I started sketching the members and then comparing the sketch
with Megastar, but we couldn't quite make sense of the chart on the
screen although the general flow of the galaxies appeared correct.
So, we tried rotating the image one way and then the other without
success. Finally, we realized Megastar was set to flip the charts
east-west and by resetting the chart everything was now right with
the universe!

Mark was curious how deep we were going. Well, we picked up three
17th magnitude (blue magnitude) members with the faintest member
2MASX J17035650+7837357 coming in at 17.4. (for comparison, I had
originally printed my chart down to 16.0).

Here are some of my other favorite targets from GSSP --
Abell 43 (17 53.5 +10 37) was visible at 175x and NPB filer as a
moderately large, round disc, ~70" diameter with an even surface
brightness. Viewing the planetary unfiltered three stars were
superimposed with the mag 14.7 central star the brightest of the
trio. Fainter stars were visible at the south and east edge of the rim.

Abell 53 (19 06.8 +06 24) was picked up at 115x using an OIII filter
as a very faint, fairly small, round disc, at least 25" diameter.
With concentration and averted vision, the planetary was barely held
continuously with averted vision.

Abell 55 (19 10.5 -02 21) appeared fairly faint at 175x and NPB
filter, fairly small, elongated 4:3 SW-NE, even surface brightness,
crisp-edged. Visible continuously in a rich star field, though there
was no indication of annularity or structure. A few very faint stars
are at the edges. Just visible unfiltered, though the outline was
not as well defined.

Abell 57 (19 17.1 +25 37) appeared faint at 225x and NPB filter,
fairly small, elongated WNW-ESE, ~30"x20". Located just 1' WNW of a
mag 10.5 star. A string of three mag 12.5 stars oriented NW-SE lies
~2' south.

Abell 61 (19 19.2 +46 15) was picked up fairly easily at 73x using
the OIII filter as a very faint, large, round disc, 2.5'-3' in
diameter. The outline of the rim was fairly well defined and the
disc was just visible continuously with averted vision and
concentration. A few stars are just within or at the edge of the rim
including one at the N edge and one just off the W edge. A group of
stars is close to the SW.

Hoag's Ring (15 17.2 +21 35) -- to me this is one of the iconic HST
images (see http://antwrp.gsfc.nasa.gov/apod/ap020909.html). The
outer ring has too low of a surface brightness to be seen with my 18-
inch but I was happy just to pick up this dim galaxy (B = 16.0). At
280x this ring galaxy appeared extremely faint, very small, round,
20" diameter, low even surface brightness. Visible roughly 1/4 to
1/3 of the time with averted vision and could hold only a few seconds
at a time. Situated just east of the midpoint of a 8' line
connecting two mag 10 and 11 stars oriented SE to NW.

2MASX J20433169+1507332 (20 43.5 +15 08) is hiding in the glare of
mag 4.4 Delta Delphini (on the main stars in the Dolphin's outline),
just 3' NNE of the bright star! At 280x it was visible as a very
faint, 15" glow of even surface brightness just visible continuously
with averted and concentration. The trick was to keep Delta just
outside the field and with tracking this was easy to accomplish.
Although very close to Delta, it still helped to use a photographic
finder chart to identify several nearby mag 14 stars including one
close SE and a N-S string of 3 stars just north of Delta and west of
the galaxy.

Hickson 85 (18 50.4 +73 21) -- I had picked up the two brightest
members HCG 85A (CGCG 341-010) and HCG 85B a couple of times
previously (only 40" between centers), but this time Mark and I were
clearly picking up an even fainter 3rd member intermittently. But
every so often, the object seemed to pop out in a slightly different
position. Jeff Gortatowsky came over and verified there were
actually 4 galaxies in the field. The fainter two members come in at
a total blue magnitude of 17.4 and 17.5!

Hickson 84 916 44.4 +77 50) resides just 42' SE of NGC 6217 in Ursa
Minor -- even closer than AGC 2256. I was able to pick up HCG 84A, B
and C (marginal)...
HCG 84A 16 44.4 +77 50 -- at 280x, the brightest member of HCG 84
appeared faint, small, elongated 5:3 N-S, ~25"x15", very weak
concentration. Located 1.6' NE of a mag 11.7 star and 2.1' SW of a
mag 11.4 star. Also nearby is a mag 14.5 star 40" WSW and a mag 15
star 40" SSE (HCG 84C is attached to this star). I also asked Paul
Alsing if we would take a look in his 25" and HCG 84C was easy to
confirm and HCG 84D was glimpsed (17.3B).

One last thanks to all those who put together a great star party,
Steve

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