Object Of The Week December 23 2018: NGC 1961 == Arp 184

[wvreeven]

NGC 1961, Arp 184, IC 2133

LINER-type Active Galaxy Nucleus

Constellation: Camelopardus

RA: 05 42 04.775
Dec: +69 22 42.17
Visual magnitude: 10.99
Dimensions: 4'.6 x 3'.0

Since I will be travelling for Xmas and will not be able to add this OOTW later, I'll do it now. Happy Xmas and all the best for 2019!

Camelopardus for some reason is a constellation that I do not visit often. But it is a constellation that is very rich in objects, both galactic and extra-galactic. One of the objects I did visit is NGC 1961.

NGC 1961 was discovered by William Herschel on December 3, 1788, so almost exactly 230 years ago. Halton Arp added the galaxy as number 184 to his famous atlas in the category Galaxies With Narrow Filaments. The galaxy lies at a distance of about 200 million light years from Earth giving it a size of over 220 thousand light years across.

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The galaxy itself appears distorted but no companion has been identified nor has a double nucleus been found indicating a recent merger. Despite that, the spiral arms are highly irregular with two straight arms extending to the north.

NGC 1961 was identified to be in a small group with 7 other galaxies. You can look them all up easily when you're observing NGC 1961 because they all lie close by as can be seen in this image.

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My own observation log with my 20" telescope reads

"At 320x the galaxy is pretty large. To the south lies a pretty bright star and between the star and the nucleus of the galaxy I see a dark lane. The galaxy continues on the other side of the star. To the west lies another star and the galaxy nearly touches the star. The Moon is still above the horizon and the SQM value is 21.2."

so I'll need to visit this galaxy again under darker skies. I am curious if you manage(d) to see the two anomalous spiral arms.


As always,

"Give it a go and let us know!
Good luck and great viewing!"

[Bertrand Laville]

Hi All,

No sketch of this object, but two old reports, with small and medium apertures, in rural skies (NELM 6.5v, SQM 21.5)

Megrez 80mm:

x36 Meade SWA 13.8mm
The galaxy is quite pale, but it is seen VI1, after qqqs seconds, without knowing in advance where it is in the field.
First suspected, then safe, then the elongation appears, low, a/b ~ 1.5, in AP ~ 107°. (note in situ: false, 80°, but the beginning of the coils which alone can impress the eye, show an AP of 95°)

x50 radian 10mm
Loneos 1961C, M12.03V appears, easy, VI2, when the adaptation is complete. However, Loneos 1961E, M13.04V is not seen.

x71 Nagler 7mm
Loneos 1961E is well regarded, VI4, but it seems to me that there are two nearby stars, of the same V, oriented in the alignment of Loneos 1961C. I look at Guide8/DSS, and there are actually 2 Loneos stars, exactly where I saw them, Loneos E, and Loneos D, M13.56V.

Meade LX200 10"

x184 Meade SWA 13.8mm
It is a beautiful galaxy, luminous, but not very contrasting.
The elongation of the halo, in AP 80°, appears, as does the central condensation, consisting of a main round part, d = 45" (the "true" central condensation), and a "boil" in AP 280°, which is in fact the beginning of the Spire W.
A star of m 13.5v on the halo, on the S-rim of the CS, The difference of mv between Loneos D and E is confirmed, in accordance with the values of Guide8;
NGC 1961 is an interesting galaxy.

Clear skies
Bertrand
http://www.deepsky-drawings.com/

[Steve Gottlieb]

This was a quick observation with Jimi's 48-inch at low power (375x):


This distorted spiral appeared as a very bright, very large oval nearly 2:1 E-W, ~3.6'x2.0', with a highly asymmetric appearance. The very bright, large oval core was clearly offset to the north side of the galaxy! A large arm sweeps E-W along the south side of the halo and a broad dust lane runs parallel to the arm on the inside. Surrounding the core are shorter inner spiral arms including an arm just north of the core that sweeps west and bends south. A mag 13.5 star is superimposed just inside the dust lane, 30" SSE of center.

[Uwe Glahn]

Nice Christmas object Wouter. Happy days and all the best to the forum.

I noted with the 27-inch: unusual and asymmetric appearance; bright core offset to the N; faint, large 1:2 elongated halo; dark lane S of the core; four small plobs within the galaxy; long, thin arm at the S end; very faint W halo part

sketch: 27", 293x-419x, NELm 6m5+, seeing III
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[Ivan Maly]

This is a big favorite that deserves a reobservation. Here is a sketch with 12" (375x, SQM 21.3):

https://3.bp.blogspot.com/-ULh7T5RSDxU/WCdllPPjHBI/AAAAAAAAB1M/0Jjxs3A4MMUi1yTCC0TNmQ6QHuz58drLACLcB/s1600/NGC%2B1961%2BNov%2B6.jpg