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View Full Version : Object of the Week, February, 2023 - IC 2375 and friends, in Puppis



Paul Alsing
February 6th, 2023, 04:44 AM
Object of the Week, February, 2023 - IC 2375 and friends, in Puppis
R.A.: 08h26m19.5s
Dec.: -13°18'10"
Size: 2.1'x 0.4'; Magnitude: 13.90 B

IC 2375, along with IC 2377 and IC 2379, form a conspicuous and tight trio of galaxies in Puppis. When I say ‘tight’ I mean that all 3 galaxies fit into a circle about 3 arcminutes in diameter! All are at a distance of about 275 million light-years.

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These guys are pretty close to the celestial equator in the northeastern part of Puppis, close to the border of Hydra, so they should be available to just about anyone in either hemisphere, and they are bright enough to be seen with a wide range of telecope sizes.

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On my zoomed-out and labeled document there is a 30’ field of view circle, just for scale, and this represents the FOV of a low-powered eyepiece for my own telescope, and way down near the bottom is MCG-2-22-11, mag 14.5. I saw this galaxy, too, but could not see its immediate neighbor, MCG-2-22-10

All 3 target galaxies are easily seen in the same FOV. IC 2375 is classified as a barred spiral, SB(s)b, nearly edge-on, mag 13.9, and in the eyepiece is it definitely elongated in about a 3-1 ratio, and in my 25” f/4 it was moderately bright with no hint of structure but with a gradually brightening center. The photos show a long tapering wing on the western end but I did not see even a hint of it on an average night from my usual observing location in the Anza-Borrego desert.

IC 2377, at mag 14.6, is the dimmest of the trio, is pretty faint and round and is essentially featureless. Its morphology is Sa, as per SkyTools.

IC 2379 is a little brighter at mag 14.4, is also pretty faint, but is a little egg-shaped, perhaps a 2-1 ratio with a stellar core, and it is otherwise also featureless. Its morphology is S0-a, as per SkyTools.

While doing some due diligence about these galaxies I came across a statement that said these 3 galaxies and the 4th, MCG-2-22-11, were part of a galaxy cluster called LDCE 0574 (Low-Density-Contrast Erratum catalogue) which is a new one for me. I will guess that someone here can expand on this snippet and fill the rest of us in, because I cannot find any more information about this catalogue!

Even though these galaxies are mostly just little gray fuzzies, they are in a really nice field and quite enjoyable to observe.

As always, give it a go and let us know!

lamperti
February 6th, 2023, 12:18 PM
Saw this small grouping back in 2002 with a 20" at 282x and was able to see them with direct vision and split them all. IC 2379 was a bit harder to see than the other two. They comprise Trio #16 in the Astronomical League's "Galaxy Groups and Clusters Observing Program.

Steve Gottlieb
February 6th, 2023, 04:45 PM
I agree, this is a nice little triplet. I first observed them in 1997 with a 17.5-inch and then again in 2015 with my 24-inch (notes below)


IC 2375: first in a striking trio of IC galaxies. At 322x; relatively bright, very elongated 7:2 E-W, ~0.8'x0.25'. IC 2377 lies 1.6' E and IC 2379 is 2.1' ENE.

IC 2377: slightly fainter than IC 2379, slightly elongated, ~0.4'x0.3', even surface brightness. Faintest (lowest overall surface brightness) in a close trio with IC 2375 1.6' W and IC 2379 0.9' NNE. A mag 11 star is 1.6' ESE.

IC 2379: fairly faint, oval 4:3 NW-SE, ~0.45'x0.3', small bright core. Second brightest in the triplet. A mag 11 star lies 1.7' SE and a slightly fainter star is 1.9' NE.

MCG -02-22-011: fairly faint, elongated 5:3 N-S, ~25"x15", small bright core. A mag 12.3 star is off the SE side [30" from center]. I picked up this galaxy while viewing the IC 2375/77/79 triplet, located 14' NNE.

LDC (Low-Density Catalog) and HDC (High-Density Catalog) are based on higher density regions in the 2MASS catalog. See formula 1 in this paper (https://arxiv.org/pdf/astro-ph/0610732.pdf) and I'm sure it will all be explained. Hahaha.

Uwe Glahn
February 6th, 2023, 05:28 PM
Found also an older observation and sketch of this beautiful triplet.

sketch: 27", 419x, NELM 6m5+, Seeing IV
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home (http://www.deepsky-visuell.de/Zeichnungen/IC2375-Gruppe.htm)

wvreeven
March 19th, 2023, 07:32 AM
I gave this group a go tonight from Rio Hurtado in Chile using my 20" dob. Even at 83x I could see IC 2375 and IC 2379. At 427x I could see all three. All were featureless and IC 2377 appeared round. IC 2375 was very oval and had pointy ends. No further structures seen.