Object of The Week August 15, 2021–Arp 169 (3 in A Row)

[Jimi Lowrey]

ARP 169 AKA NGC 7236,NGC 7237 and PGC 200377

Galaxy Triplet

Pegasus

RA 22 14 46
Dec + 13 50 59

MAG
7236 14.4
7237 14.0
PGC 200377 approximately 16.0 ?

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I am filling in for Dragan this week he is on vacation.

Arp 169 is one of my favorite type of objects a galaxy triplet. Although only two of the galaxies are interacting NGC 7236 and NGC 7237. The faint PGC 200377 is foreground of the group by 30 million light years. PGC 200377 is called NGC 7237C in NED I could not find out why this is if anyone knows I would be interested in the story. Albert Marth found 7236 and 7237 on August 25, 1864. I am not sure if he caught PGC 200377.

92B9FA8C-F87F-4431-B89C-A512FD0AF2A8.jpeg

My observations of this small group I see 7236 and 7237 fairly bright encased in a common halo. PGC 200377 is direct vision in the 48” I find this small group best a 610X on this night. I highly recommend this group.

Be sure next time out to try Arp 169 galaxy triplet,

Give It A GO!
Good Luck and Great Viewing

[lamperti]

Back in 2009, with a 20" at 313x, I found NGC 7236 the brightest of the three in a string with a brighter center, NGC 7237 round and a bit dimmer than 7236, NGC 7237c was a small averted vision1 glow.

[Steve Gottlieb]

I believe it's possible this is a triple merger. The redshift of PGC 200377 (z = .024) is ~10% less than NGC 7236 and 7237 (both z = .026). Perhaps the difference is caused by individual motions (not Hubble flow) if PGC 20037 is "falling" into the merger from the backside.

I like that the three galaxies (first seen in my 17.5" back in 1988) are neatly arranged in a NW to SE line, equally spaced, and in order of visibility! (NGC 7236 - 7237 - PGC 200377) The last one was visible, though fairly tough (V ~15.7) in my 17.5", but it could be held steadily in my 24".

--Steve

[Clear Skies]

Two out of three were visible in my 12" SCT in September 2013, 179x / 27':

Only the two NW galaxies (NGC7236 and NGC7237) are visible, the SE galaxy PGC200377 is not visible.The NW galaxy (NGC7236) is brighter than the galaxy to the SE is (NGC7237), both are faint, round fuzzies, even in brightness, no detail visible and difficult to observe when not using AV.

Arp 169-1.jpg Arp 169-2.jpg Arp 169-3.jpg

Click here to download the observing guide.

[wvreeven]

My observation with my 20" in 2015:

At 545x NGCs 7236 and 7237 and UGC 11958 are visible in the same field of view. NGC 7236 is a large, elongated patch of light. A bar is visible perpendicular to the major axis of the galaxy. NGC 7237 is a large, elongated patch of light with the major axis directed to NGC 7236. It has a slightly brighter central region. UGC 11958 is a faint glow.

[Uwe Glahn]

Really cool object Jimi. I add my result with my 27-inch.

sketch: 27", 419x, seeing III, NELM 6m5+
NGC7236_NGC7237.jpg
home

[akarsh]

Hello from Okie-Tex Star Party, held in the north-western tip of Oklahoma. I took a look at this object last night when we had decent seeing and moderate transparency. There was apparently also some smoke in the air, but the views were good last night overall.

Coming to this group, the two NGC cores were easy-ish in a 7mm Nagler or 6mm Delos in the 18". The NGC 7237 core seemed to have a halo that was lopsided to the south-east. I had not made notes on what to expect with this object, so I assumed the third object (PGC 200377) could be a star at first, later realizing that it might be a third galaxy. I logged it as "very faint".