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Old 07-10-2019, 01:00 PM
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ngcles
The Observologist

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Join Date: Dec 2006
Location: Billimari, NSW Central West
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Agc 3627 & eso 137-6

Hi Ron & All,

Quote:
Originally Posted by astroron View Post
One of my favourite observing targets is the ESO 137-6 and the group round it.
It is also situated on the Norma, Triangulem Australe border.
If you haven't observed it it would be a good target for your scope.
Cheers
Ah yes the Abell cluster (AGC 3627) near the purported centre for the "great attractor".

Have tilled that ground a few times myself in my old 30cm and the 46cm. I think it is quite a challenging cluster to (visually) observe due to the blizzard of faint foreground stars. Makes tracking-down, finding and seeing the little 'uns a pain in the neck.

Perhaps a little tangential to the thread topic, here are my notes of AGC 3627 made from Mudgee about 2am, 18th April 2010 with the 46cm f/4.9 at x120 and x247. The SQM-L reading was 21.62 and seeing was 6/10:

PGC 57532 (ESO 137-1) Gx Triangulum Australe
46cm x247: ESO 137-8 is the brightest of a large number of galaxies in AGC 3627 that includes ESO 137-1 (PGC 57532) 20’ NW, ESO 137-2 (PGC 57537) 16’ WNW, ESO 137-3 (PGC 57546) 16’ SW, ESO 137-6 (PGC 57612) 5’ WNW, ESO 137-7 (PGC 57637) 15’ N, ESO 137-10 (PGC 57652) 7’ NNE, ESO 137-11 (PGC 57656) 4’ NE and ESO 137-16 (PGC 57815) 26’ ESE. This is a challenging and frustrating galaxy cluster to observe because to the richness of the star-fields and the bright background due to the Milky Way. Makes identification difficult because star-patterns are very easy to confuse because there simply are so many stars. All these galaxies have low to very low surface brightnesses and it is nearly impossible to properly estimate sizes in the eyepiece because of the brightness of the background sky. From the trio of ESO 137-6, ESO 137-8 and ESO 137- 10 5, one field W is the 15' long line of ESO 137-1, ESO 137-2, ESO 137-4 & ESO 137-3 running N-S. ESO 137-4 is almost between ESO 137-2 & ESO 137-3 as a tiny 20" diameter round spot of gossamer hardly brighter than the background as is ESO 137-1 at the N end of this line.

PGC 57537 (ESO 137-2) Gx Triangulum Australe
46cm x247: From the trio of ESO 137-6, ESO 137-8 and ESO 137- 10 5, one field W is the 15' long line of ESO 137-1, ESO 137-2, ESO 137-4 & ESO 137-3 running N-S. Of this four, ESO 137-2 & ESO 137-3 are the brightest though ESO 137-3 has lower SB and is a little bigger. ESO 137-3 is about 1' x 40" and brightens weakly to centre and has very LSB. ESO 137-2 is smaller, about 40" diameter, round but has better SB brightening slightly to centre.

PGC 57546 (ESO 137-3) Gx Triangulum Australe
46cm x247: From the trio of ESO 137-6, ESO 137-8 and ESO 137- 10 5, one field W is the 15' long line of ESO 137-1, ESO 137-2, ESO 137-4 & ESO 137-3 running N-S. Of this four, ESO 137-2 & ESO 137-3 are the brightest though ESO 137-3 has lower SB and is a little bigger. ESO 137-3 is about 1' x 40" and brightens weakly to centre and has very LSB. ESO 137-2 is smaller, about 40" diameter, round but has better SB brightening slightly to centre.

PGC 557554 (ESO 137-4) Gx Triangulum Australe
46cm x247: From the trio of ESO 137-6, ESO 137-8 and ESO 137- 10 5, one field W is the 15' long line of ESO 137-1, ESO 137-2, ESO 137-4 & ESO 137-3 running N-S. ESO 137-4 is almost between ESO 137-2 & ESO 137-3 as a tiny 20" diameter round spot of gossamer hardly brighter than the background as is ESO 137-1 at the N end of this line.

PGC 57612 (ESO 137-6) Triangulum Australe
46cm x247: ESO 137-6, ESO 137-8 & ESO 137-10 in a triangle with ESO 137-10 at the northern tip. This triangle is about 6 arc-mins a side. ESO 137-10 is seen to be slightly elongated in PA 0 and is the brightest of all. It has a short line of three magnitude 12-13 stars not far to the W. 1.5' x 40" in PA 0 and has a small slightly brighter core. ESO 137-06 & ESO 137-08 are E-W of each other and are simple, approximately 1' diameter spots of LSB haze brightening slightly to centre. Between ESO 137-10 & ESO 137-8 is ESO 137-11 which is somewhat to much fainter -- a spot of mist perhaps 30" diameter with a weak central brightening.

PGC 57637 (ESO 137-7) Gx Triangulum Australe
46cm x247: A line extended from ESO 137-8 through ESO 137-10 and extended N about 10’ sees ESO 137-7 that is similar to ESO 137-11 though it has slightly higher SB.

PGC 57649 (ESO 137-8) Gx Triangulum Australe
46cm x247: The major three galaxies here are ESO 137-6, ESO 137-8 & ESO 137-10 in a triangle with ESO 137-10 at the northern tip. This triangle is about 6 arc-mins a side. ESO 137-10 is seen to be slightly elongated in PA 0 and is the brightest of all. It has a short line of three magnitude 12-13 stars not far to the W. 1.5' x 40" in PA 0 and has a small slightly brighter core. ESO 137-06 & ESO 137-08 are E-W of each other and are simple, approximately 1' diameter spots of LSB haze brightening slightly to centre.

PGC 57652 (ESO 137-10) Gx Triangulum Australe
46cm x247: ESO 137-6, ESO 137-8 & ESO 137-10 in a triangle with ESO 137-10 at the northern tip. This triangle is about 6 arc-mins a side. ESO 137-10 is seen to be slightly elongated in PA 0 and is the brightest of all. It has a short line of three magnitude 12-13 stars not far to the W. 1.5' x 40" in PA 0 and has a small slightly brighter core. ESO 137-06 & ESO 137-08 are E-W of each other and are simple, approximately 1' diameter spots of LSB haze brightening slightly to centre. Between ESO 137-10 & ESO 137-8 is ESO 137-11 which is somewhat to much fainter -- a spot of mist perhaps 30" diameter with a weak central brightening.

PGC 57656 (ESO 137-11) Gx Triangulum Australe
46cm x247: Between ESO 137-10 & ESO 137-8 is ESO 137-11 which is somewhat to much fainter -- a spot of mist perhaps 30" diameter with a weak central brightening.

PGC 57815 (ESO 137-16) Gx Triangulum Australe
46cm x247: Far off the E side of the cluster ESO 137-16 sits all by itself -- a small 30" diameter spot of very LSB mist with no detectable brightening to centre.


Best,

L.

Last edited by ngcles; 07-10-2019 at 01:40 PM.
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