Object of the Week May 11, 2025 – NGC 3338

Spiral galaxy
Leo
RA: 10 42 07
Dec: +13 44 49

Attachment 5706
Depending on the source, NGC 3338 is anywhere between magnitude 10.9 and 12.5. It’s approximately 75 million light years away, and about 129,000 light years in diameter. It has an apparent diameter of 5.9 x 3.6 arc minutes, although visually it appears smaller. Photo by Adam Block: https://en.wikipedia.org/wiki/NGC_33...ile:N3338s.jpg


I came across NGC 3338 for the first time in April 2025 while I was under a very dark and enjoyably transparent sky. I couldn’t have been more surprised at the darkness, given we’re in a strong solar max cycle, but the excellent conditions motivated me to observe all night. Who knows when I’ll find a sky this dark again?

I was at Chickahominy Reservoir in southeastern Oregon, my go-to dark sky site. The skies here are usually quite good, and the campground is almost always nearly deserted. Not this time – the place was overrun with people who came for the opening of the fishing season! Fortunately, fisher-folk go to bed early, so I had the night sky to myself.

I observed NGC 3338 just before I had a long look at the Antennae Galaxies, NGC 4038 and NGC 4039, and was able to see the beautifully long and curved tidal tails for the first time with a scope smaller than 48-inches. But that’s another story.

As you can see from Adam Block’s image above, NGC 3338 is not a barred spiral, but it sure looked like one in my 30-inch f/2.7 scope at 297x. The seeing wasn’t steady enough to go beyond 297x, and I wonder if I would have seen its inner spiral arms with steadier seeing and more power. Regardless, the view was wonderful as it was, and I did see the two main spiral arms. Here are my observing notes and eyepiece sketch:

“Oh yeah! This is a beautiful spiral that looked more detailed the longer I looked at it. (It looks like) another barred spiral with a long and bright bar. The core is distinctly brighter. Rather large and set in an attractive star field. 297x, 21.95 SQM.”

Attachment 5707 Attachment 5708

There are loads of galaxies to observe in Leo, and even though I just randomly picked this one on an exceptional night, I think it’s worth the time to observe for anyone interested in spiral galaxies.

Give it a go and let us know!

Back in April 1987 using a 17.5" at the time, I logged the galaxy as

Fairly bright, fairly large, broad concentration to an elongated brighter core with a brighter nucleus embedded, hints of internal structure. The fainter outer halo is elongated 3:2 E-W in the direction of mag 8.7 SAO 99253 which lies 2.7' W of center.

I didn't mention a bar (or in a later observation with my 18"), but an "elongated brighter core" is certainly bar-like.

An observation made in 1854 by R.J. Mitchell with Lord Rosse's 72" is interesting --

"Bright nucleus, round, about 2' diameter, light irregular, has a second minute nucleus preceding the large one? Spiral?"

I wonder if the "second minute nucleus" might refer to an H II knot to the west of the nucleus? And he apparently saw evidence of spiral arms, but wasn't confident.

Hi, here's my observation from 4/5/2024: Ngc 3338 spiral galaxy in Leo; magnitude:10.72 ; size: 1.2' x 0.7' ; fairly bright and elongated with a slightly brighter core. I used a 8mm Ethos at 240x with my 14.5 StarStructure f/4.3
Attachment 5709

I'll have to give this a try next week, weather cooperating . . . Wonderful observation and sketch Howard.

I can contribute another sketch of 3338. For me the fainter arms and outliners were clearly visible as thin arm segments. The inner structure was more difficult and only indicated with one bend dark structure and two brighter sections.

sketch: 27", 419x, NELM 6m5+, Seeing III
Attachment 5710

With my 20" from SQM 21.0 skies on March 3rd 2016:

At 427x visible as an elongated glow pointing at a bright star. It has faint outer regions with a bright central region and a stellar nucleus. I have the feeling that the galaxy is bent a bit. To the north lie two fainter stars and I have the feeling that the galaxy is bent that way, but this is a doubtful observation.

Very nice sketch Uwe - that’s what I hoped to see!