Object of the Week, 3 April 2022 - An obscure alignment in UMa

[Clear Skies]

Spring is here. Galaxies galore. For this week's OOTW I decided to go with an obscure group in Ursa Major. Some aperture required.

UGC7064A lives in the north-northeastern regions of the Great Bear. Brightest galaxy in the vicinity is NGC3945, 1.4 degrees to the east.

But if it carries the designation UGC7064A, there sure must be a UGC7064 without the A..? There is, but it's 29 degrees to the south-southwest, also in Ursa Major and better known as the group Holmberg 232 / Rose 8 / KTG 41.

Here is our object of the week, @ 12:04:44 +60d40m20s. Both images are only 5 minutes of arc in size:

dss.gif sdss.jpg

In NED it is listed as a galaxy triple with a population count of 4 (...). It's a bit of a confusing mess when it comes to designations. Let's break it down.

Starting in the west, we see a bright little fellow. NED designates it UGC7064A NED01. But it's a star, as confirmed by SDSS, known as 4UCAC754-046749 (a.k.a. SDSS J120441.17+604019.3).

West of center is the brightest galaxy of the bunch: PGC38217, UGC7064A NED02. SIMBAD says this is both UGC7064A & B, where NED does not list anything other than -A, but only for the group as a whole. Its nucleus is a tad fainter than the star to its west appears to be.

Directly north-northeast is an extremely faint one: SDSS J120443.44+604027.3, (.2 in NED, but that may be a typo).

To the east of PGC38217 is PGC200281, UGC7064A NED03. Like its sibling to the west it is very small and faint, but it does sport a prominent dark lane along with a nucleus. SIMBAD says it's UGC7064C.

I think it's clear to conclude that the two PGC galaxies are interacting. The long east-northeast to west-southwest extending lane, that appears to be passing through both galaxies, is evident.

The easternmost galaxy is SDSS J120448.91+604019.6. It too reveals a nucleus. Its redshift indicates it is in the distant background and not a physical member of this group.

There's little to none information about this group on the web. This image on Flickr is a beauty, though: https://www.flickr.com/photos/geckzilla/48267298226
As the image reveals, SDSS J120441.17+604019.3 is indeed as star. To its west, on the western edge of the extending lane, is yet another faint galaxy. It may be SDSS J120439.72+604016.1, although classified as a star in SDSS.

As always, I have pieced together an observing guide for this OOTW. Click here to download it.

UGC7064A-1.jpg UGC7064A-2.jpg UGC7064A-3.jpg

Well... you know what to do! Use Jimi's scope, and let us know.

[Uwe Glahn]

Got the chance to visit the "alignment" last new moon.

While the star within the galaxy and the nuc were an easy catch, the spot in the east was hard to see but manageable.

sketch: 27", 586x, NELM 6m5+, Seeing II-III
UGC7064A.jpg
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[akarsh]

Steve Gottlieb brought this object to our attention when we were observing on Jimi's 48" recently. A paper that led to it's Hubble Image, with William Keel as the PI (https://arxiv.org/abs/2202.01098), calls this system an "overlap". It's interesting that the two PGC galaxies might be interacting, which puts a potentially different spin on this.

Through Jimi's telescope, we were able to see an edge-on with an overlapping star and 2 galaxies, one (PGC200281) much fainter than the other (PGC38217). I saw the smaller overlapping galaxy as being bigger at the eyepiece, perhaps because the dust from the bigger one rendered it lower in surface brightness, and therefore we were only seeing the core of the larger galaxy. I believe Steve had the same results at the eyepiece.

I did not look for the background galaxy SDSS J120448.91+604019.6 -- perhaps Steve, Howard or Jimi did?

Here is my sketch of the system through Jimi's 48". I would love to know what this system is.
UGC7064A.jpeg