Object of the Week, February 7 2021 - A wide northern pair in Camelopardalis

[Clear Skies]

High in the northern sky, a mere 10 degrees from Polaris, in a seemingly barren piece of sky, we find a wide pair that goes by KPG 132. One of the 603 entries in Karachentsev's list of Northern Isolated Pairs of Galaxies.

This pair in the northeastern part of Camelopardalis consists of the galaxies NGC2336 and IC467.

Object: KPG 132 - NGC2336 & IC467
07:28:19 +80d00m00s
Constellation: Camelopardalis, the Giraffe
A - NGC2336: 07:27:04 +80d11m00s
B - IC467: 07:30:18 +79d52m00s

There are no bright stars nearby that can work as lead-in features, but there are a few further out. A degree-and-a-half to the east is the mag. 5.3 star SAO6392 / DB+79 00265 and 2 degrees west is mag. 5.4 SAO5946. Just over 2 degrees to the north is the variable star VZ Camelopardalis, shining bright orange at mag. 5.1. 3 degrees to the south-southwest is SAO6022 / BD+77 00266, bright at mag. 4.8 and ruddy thanks to its K4 spectrum.

KPG 132A - NGC2336 was discovered in the year 1876 by German astronomer E.W.L. (Wilhelm) Tempel, using an 11" refractor he dubbed Amici 1, at Arcetri Observatory in Florence, Italy. Tempel, who was awarded the Lalande Prize by the French Academy of Sciences in 1861, is also credited with the discovery of the nebula surrounding the star "Merope" (23 Tauri) in the Pleiades that we know as NGC1435: "Tempel's Nebula". Tempel is known for his comet discoveries, 21 in total. The most famous one perhaps being comet 55P/Tempel-Tuttle he discovered in 1865, the source of the annual Leonid meteors. Also, the comet 9P/Tempel he discovered in 1867 was the target of NASA's Deep Impact mission.

NGC2336 is classified as a spiral galaxy of the mixed bar family with an inner ring and a Hubble stage between Sb and Sc. It is also a type 2 Seyfert galaxy. It is at a distance of approximately 30 Mpc with an HRV of 2204 km/s, translating to roughly 90 million light-years and a diameter of about 200K light-years.

15' DSS POSS2 Blue & an image from Hubble
2336 15.gif

The galaxy is elongated north to south with a dimension of roughly 8 x 4 arcminutes and sports a relatively small, bright core. A mag. 14.8 star is superimposed, due east of the center. Further out are several prominent arms of which the southern one is the brightest. Despite these arms showing some signs of distortion this galaxy has not made it into any catalogs of distorted galaxies. Larger apertures will reveal is spiral structure, of which I was able to glimpse a hint under dark skies in the French Ardennes in November 2018 with my weapon of choice, a 14" SCT @ 168x/29':

NGC2336 is quite a large and bright, north-south elongated galaxy, suddenly brighter in a small core that is slightly elongated in the same direction. East of the center is a mag. 14 star foreground star (4UCAC851-007537). Using AV spiral structure (irregular structure) can subtly be discerned, but no individual arms. A beautiful galaxy.
PGC213387 to the NNE is not visible.

I rated it 7/10.
A noted in the observation above, NGC2336 has a companion. PGC213387 is an extremely small and faint smudge, 3' to north-northeast. I have not seen any data for this little one such as its HRV, but I suspect it is in the distant background. On closer inspection its spiral form is revealed and I suspect such structure would not have remained intact had it been a close neighbour of NGC2336. It is probably just a chance alignment.

The second galaxy of this Karachentsev pair, KPG 132B - IC467 was discovered on 7 November 1890 by W.F. (William) Denning using a 10" reflector from Bristol, England. Denning was a cricketer, discoverer of four comets, recipient of the Gold Medal of the Royal Astronomical Society in 1898 and he is known for his planetary observations, especially of Jupiter. His book "Telescopic Work for Starlight Evenings", published in 1891, is a free e-book download.

On page 342 of his book, Denning notes: "While comet-seeking in 1889 and 1890 I discovered ten new nebulae, all near the N. pole." On of these was the galaxy IC467, which he notes as "very faint, pretty small".

15' DSS POSS2 Blue
IC467 15.gif

IC467 is 20 arcminutes to the south-southeast and is roughly 2/5 the size of NGC2336. Like its larger sibling it is classified as a galaxy of the mixed bar family, but of the S-shaped variety Hubble class c. On the southwestern edge is a mag. 14.7 star (4UCAC850-007667). Its arms and small dark regions will be much harder to distinguish than the details in NGC2336, but in my aperture it did appear irregular to me:

Quite a faint, WSW-ENE elongated, irregular glow. Using AV the galaxy is flattened on the SSW side on a line from east to west. No dark regions can be discerned. Using AV the galaxy has somewhat irregular structure. To the WSW, detached from the galaxy is a mag. 14.5 star (4UCAC850-007667).

I rated this one 4/10.

On my website, I have posted CSOG style observing guides for this object, available for download: clearskies.eu/csog/downloads/dsfootw

KPG 132.jpg

As always: Give it a go and let us know!

[Ciel Extreme]

This is an observation from seven years ago in my backyard with an 18-inch Litebox telescope using a Baader Hyperion 10mm eyepiece for a magnification of 207x. Visual limiting magnitude was mag. +5.7.

NGC2336
This galaxy is large, bright and diffuse, a large oval disk with ill-defined edges, oriented due N/S. Averted vision brings out the faint extremities. A brighter, fairly large core is embedded; a faint field star is immediately east of the core and the disk is a little grainy. A busy foreground of moderately bright field stars enhances the field.

IC467
IC467 is a little dimmer than NGC2336 but well seen as a large, elongated disk, uneven in surface brightness and extended ENE/WSW. The edges are a little ill-defined and there is no brightening to the core. A triangle of field stars, two bright and one faint are situated to the north, pointing directly at the galaxy. To the SE is a scattered group of a half dozen very faint stars.

[Howard B]

Victor's OOTW inspired me to observe NGC 2336 and IC 467 a couple nights ago, and they were the first objects on my observing list. Transparency was awful as the sky became nearly overcast at the end of my observation so these two galaxies were the only two deep sky objects I was able to observe. Here are my notes:

"Good thing this was my first observation of the night - the sky was starting to cloud over just as I found it - dang! I had a decent look but conditions are awful and getting worse. Anyway, 2336 is quite large and stood out best at 155x. A condensed core and bright non-stellar center is surrounded by a huge elliptical and faint glow - this would look awesome on a decent night. IC 467 was a faint elongated glow, also bigger than I expected at 253x. About a half degree apart, I'll come back for better look. No SQM."

N2336_IC467_stars.jpg N2336_IC467_invert.jpg

On the other hand, the seeing was excellent and even though the clouds were covering the sky there were frequent holes that opened up, and I took the opportunity to try for Sirius B. Success! I'll post my observation elsewhere though.

[Clear Skies]

NASA Sure loves our Objects of the Week! First Steve’s VY Canis Majoris nebula https://www.nasa.gov/feature/goddard...-stars-dimming, now NGC2336 https://www.nasa.gov/image-feature/g...ul-blue-galaxy only a few days later.