Object of the Week December 3, 2024 – Four Open Clusters: NGC 133, NGC 146, King14 and Pot 7

[Howard B]

Open Clusters
Cassiopeia
RA: 00 32 33
Dec: +63 14 17
(coordinates to the center of the grouping)

king14_ngc146_133-RGB_Gregg L Ruppel.jpg
(NGC 146 is on the upper left, NGC 133 is on the upper right, King 14 is below NGC 133 about halfway to Kappa Cass, and Pot 7 is below NGC 146. Pot 7 is the most linear looking cluster of the bunch. Photo credit: Gregg L. Ruppel, https://greggsastronomy.com/King14.html)

First of all, a mea culpa – I missed the Sunday deadline for this OOTW because I forgot it was my turn. No excuse! My apologies to all. However, I did have this group of open clusters in mind for my next OOTW, so I haven’t been completely negligent. Let’s dive in.

This past November 6, I was observing in my backyard, and after coming up empty on a few previous objects I decided to go for some bright open clusters in Cassiopeia. Flipping to chart 15 in the Interstellarum Deep Sky Atlas, I noticed a clump of three open cluster just north of the 4.2 magnitude star, Kappa Cass. A closer look at the atlas showed a fourth - Pot 7 - plotted to indicate it is less visible than the other three. "Hmm" I wondered, "what is a Pot open cluster?"

This seemed interesting so I pointed my scope (30-inch f/2.7) at Kappa, and was immediately gratified to see four clusters! Here are my notes:

“These four clusters are very near Kappa Cass – all four and Kappa fit comfortably in the 140x field of view. K14 is a beauty, and is the richest of the bunch – lots of faint stars. The other three are rather linear, scraggly clusters that nearly point radially at Kappa. Quite the sight! 20.24 SQM.”

NGC 146 was discovered by John Herschel in 1829, while NGC 133 was discovered by Heinrich d’Arrest in 1865. King 14 was discovered by Ivan King sometime between 1949 and 1966 but I can’t find any info to pinpoint the exact year. More frustratingly, I still don't know anything about the designation Pot, and when Pot 7 was identified – but I’m hopeful that several readers here can give us some background.

Because seeing only two clusters in the same field of view is rare, I think these four are a real treat - and they should be accessible to scopes much smaller than 30-inches. Give them a go and let us know!

[Clear Skies]

The asterism southeast of NGC146 is Pothier 7.

DSF OotW 2024-48 - NGC133, NGC146, King 14, Pothier 7 Cas-1.jpeg DSF OotW 2024-48 - NGC133, NGC146, King 14, Pothier 7 Cas-2.jpeg

https://clearskies.eu/csog/downloads/dsfootw2024/#48

[wvreeven]

Nice choice!

As it happens I wrote an article about the Milky Way in Cassiopeia last week for the Dutch AstroForum because we chose NGC 663 to be Object Of The Month. There are dust clouds in Cepheus and Persues that block the view but in Cassiopeia we look between those clouds out of our Orion-Cygnus arm into the Perseus arm. That arm is one of the two dominant spiral arms of our Milky Way and in Cassiopeia we look towards a part that is particularly rich in open clusters.

According to Sky Vistas NGC 146 and King 14 may be related since they lie at approximately the same distance while NGC 133 is a background object that lies about 1100 ly more distant. The distances listed in Simbad don't seem to support that theory though since they put NGC 146 a few hunder pc further away than King 14.

[Raul Leon]

Hi, here's my observation from 11/25/2024: Ngc 136 open cluster in Cassiopeia ; magnitude:11.0; size: 3.3' ; very faint, small and compressed ; I used a 8mm Ethos at 238x with my 14.5 StarStructure f/4.3
ngc 136.jpg