There were a number of quite distant Galaxies (Super Spirals and BCGs) that I didn't manage to attempt this Spring due to weather and my dark sites being snowed in; All are low surface brightness and generally they need to be attempted near their culmination, under decently dark skies: Now many are falling into the West; and the Summer -the inner- Milky Way is rising to its late Summer prominence.
For those who are smitten with the Deep Galaxy bug and want to get a jump on the ones on the other side of the Milky Way, through the Southern Window, I offer this small selection: Some of these are 10-12" and up, others are more like 18-20" class, but dark sky is the main limiter of course: These are among the most likely visually detectable at such distance; complied from multiple catalogs. You can check CDS, NED, HyperLeda for details:
Fall is coming...Happy hunting!
I thought I would follow up on a few of your suggestions at last week's central California star party (CalStar) at Lake San Antonio. Both transparency (SQM 21.4-21.5) and seeing were off from previous years, though dark enough to easily surpass the 1 billion l.y. threshold with my 24" Starstructure.
PGC 97456 in Aquarius and PGC 71834 in Pisces have similar redshifts (z = .083 and .084) and light-travel times of 1.1 billion years. PGC 97456 is the BCG (brightest cluster galaxy) in the Abell cluster 2448 and PGC 71834 is the BCG in the SDSS cluster [GMB2011] 1462. Although their listed magnitudes are similar (about V = 14.5), I found PGC 97456 more prominent (visible continuously), despite being nearly 10° further south. But I logged PGC 71834 as larger (~0.3' diameter) than 97456 (~0.2' diameter).
LEDA 188874 is also in Aquarius and well placed this time of year. This one is over a magnitude fainter (B mag close to 17) and quite small. At z = .137, the light-travel time is ~1.8 billion years. It only popped intermittently for me, though the galaxy is partially "masked" by a mag 15.7 star only 20" NE. The position was pinpointed using a nearby galaxy (CGCG 375-048) 8' E and 9th magnitude HD 204738, a similar distance NE. LEDA 188874 forms the southwest vertex of an equilateral triangle with these two objects.
As far as distant galaxies, I also took a look at IC 1757 = LEDA 174458 in Cetus, which was discovered visually by Barnard, probably with the 36-inch refractor at Lick. Its redshift is similar to the first two, so tops the 1 billion year threshold. This galaxy is just 1.5' east of IC 1756 = UGC 1429, a faint (but brighter) edge-on that lies in the foreground. The SDSS image of the pair is here. HyperLEDA and SIMBAD don't recognize the IC designation, but NED does.