Object of the Week for February 16, 2025 – NGC 609

Open Cluster
Cassiopeia
RA: 01 38 08
Dec: +64 39 43

Attachment 5661
(Photo by Bernhard Hubl: http://www.astrophoton.com/NGC0609.htm. NGC 609 is 11th magnitude and is about 13,000 light years away. It has an apparent diameter of 3 arc minute, making it about 11 light years across.)

I missed the Sunday deadline for my OOTW again! My sincere apologies, I really need to pay closer attention to when it’s my turn.

I was observing from my semi-dark backyard on a rare clear night in January with my 30-inch f/2.73 scope, and came across another gem of an open cluster in Cassiopeia – NGC 609. My observing notes tells the tale:

“Wow, this is a cool open cluster! I was about to write this off as one of those invisible open clusters when my eye caught a faint glow. Small and faint – and made up of maybe a hundred or so faint stars. I imagine this would be quite beautiful in a darker sky. There’s a nice double star on the south edge of the cluster. 235x and 297x, 20.26 SQM.”

I’m not sure I would have seen this cluster with a smaller scope under my relatively bright and not so transparent sky, so this may be best saved for a night with good observing conditions. It's now on my shortlist the next time I can get myself to a darker sky, where this little puff of stardust will no doubt be an even more enjoyable sight.

Give it a go and let us know!

Saw this back in 2003 with a 20" at 282x: "Quite faint adjacent to a pair of field stars. Can just about make out some resolution." My notes say it is also called King 3.

I found NGC609 with my 8-inch SC back in the end of March 1997 (during the Hale-Bopp nights when the comet was at its brightest). NGC609 was faint, diffuse and the cluster was similar to a faint comet. No individual stars could be seen with low magnification (64x and 135x). A little bit challenging with smaller apertures.

/Timo

From SQM 21.0 skies west of Madrid, Spain, in September 2015:

This is a very spectacular, faint cluster. At 320x I see a fairly large group of faint stars of about 7 or 8' across next to a bright star. Very impressive!

I've only observed the cluster in my 24" with a significant moon up (bright sky) and poor seeing, so I had to stick to fairly low power.

At 200x; ~15 faint to very faint stars sparkle over an unresolved background glow ~2.5' diameter. Two brighter mag 12/13 stars are detached, just off the southwest end. The cluster is 2.5' NW of MLB 187, a 5" pair of mag 9/9.5 stars.


Steve

Very nice choice, Howard. Last night I pay NGC 609 a visit with my small 99mm spotting scope under good conditions. It was difficult to see, especially with the low magnification of 30x, but 50x brings out the cluster very good with some mottling within the glow but of course without showing individual stars.

Last years I systematically observed the King Clusters, where NGC 609 is King 3. My observing project (only in German) reaches from apertures from 4" to 27". In summary, even the 27" was not able to fully resolve this beauty.

I have only one observation of this object made about 30 feet away from Howard's 30-inch at the 2023 Golden State Star Party. Through my 18" at 144x I logged "Resolves into a dense cluster of faint stars. Reminiscent of a diffuse GC like NGC 5053. Elongated."