Open clusters in Cepheus (NGC7129 confusion)

[AndyWB]

On Monday night, before the moon came up, I decided to try to figure out my confusion about open clusters in Cepheus. I don't know why, but I often seem to get confused about some of them, and I think I've an idea what's up - something strange seems to be going on.

I started with a look at Delta Cepheus, just 'cos it's famous, but it's actually a very pretty double.

Then I trundled down to NGC7235 - a fuzzy dim speckling of an open cluster with a lovely deep red star and slightly brighter orange star within it. Sky Safari shows it as Magnitude 7.7.

Next I tried NGC7261 nearby. This was very faint - there, but at the limits of what I could observe. Sky Safari shows this as Magnitude 8.4.

I then found NGC7160, which at mag. 6.1 was pretty bright. I like it; it's dinky, and looks sort of glittery wonky L.

Finally, before moonrise, I went for NGC7129 and NGC7142. Sky Safari shows both of these as Open Clusters, but Wikipedia suggests that 7129 is an nebula with associated open cluster.

I thought NGC7129 was visible as a fuzzy patch, with a few stars in it. No detail, but definitely there. However, at mag. 11.5, this is rather dimmer than I'd expect to see in my scope - especially as NGC7261 was at the limit really at 8.4.

NGC7142, the other open cluster was not visible at all. At mag. 9.3, this fits with my other observations.

So, my question is what was I looking at that I thought was NGC7129 (was it?), and why could I see it? Was the fact that it is probably a combination of open cluster and nebula why I could see it? I'm pretty confident about the location; it seemed in the right place. Or are there multiple things at this location and they can be confused?

[cotterless45]

I have viewed NGC 7129 as a mag 11.5 small nebula cluster . You would be picking up nebulosity illuminated by the cluster.

I have a note that it is about 1 degree from the nebulosity of NGC 7133. Also at a similar distance is the brighter open cluster (9.3) NGC 7142, which you did not see or maybe you saw as either of the above !

Well done once more for posting with such interest and gusto , never should cease to amaze , a simple scope at one end !

Very often some degree of visual surface brightness caused by clusters illuminating their nebulosity will make them simple to see with transparent seeing, other nights they just go.

Old Nick.

[AndyWB]

Ooo - NGC7133 has lead to some interesting discussions - apparently, it may not exist: http://martingermano.com/N7129_LBN497_1024.htm

I decided to check Stellarium. There was quite a distinctive shape of stars to the left of my FoV, which I've marked, and I was using this to point (also marked) to where I thought NGC7142 should be. Stellarium seems to suggest this is right!

Whatever I saw was above that line, pretty much where Stellarium shows NGC7133 - but it doesn't label it with a nebula or open cluster marker!

It could've been 7129 or 7133 that I saw, then, assuming that they both exist. If they don't, then I think that Stellarium is confused about them too. It did look like the image for NGC7133 - a couple of stars in a fuzz.

Also, I'm sure that I didn't see NGC7142, but that makes no sense; it's supposed to be 6 times brighter? Unless it's some effect of the nebulosity?

I guess I'm going to have to revisit this!

It's easy to post with interest - it's interesting! Though I do find the 'Okay, I'm looking at something, what the heck is it?' a bit ... frustrating. Much more so, oddly, than not being able to find something I'm looking for!

 

[AlexB67]

I know the feeling Andy, I don't think it is strange, the getting there and finding but knowing you got there is satisfying, it those not sure moments that bug me when they happen, and afterwards I'd be straight into Stellarium wondering was it ..... ?? , often making a sketch helps but often I do not this and rely on memory,  anyway, you are not the only one   Luckily, for me mostly it doesn't happen that often, but I am sure as I start pushing for the harder targets that may well be a more frequent occurrence and I will have to be more thorough with notes taking, some drawings, usually for me this means a few ballpoint blobs, just to get an idea to nail the location rather then what it looks like in my notes, but also to memorise and print it in the brain  

Interesting thread, this little bit of area has been on my todo list in more serious fashion to go through, but need a good site for that fainter stuff, as soon as the clouds go away, it has been a while around here since that happened.

[andrew63]

Some interesting targets - just been looking for some further details on these objects for future reference. The image of 7129 resembles your observations - it looks a bit like the trapezium.

NGC 7129 - DeepSkyPedia :: Astronomy

And what a lovely image of the pair.  

APOD: 2007 September 13 - NGC 7129 and NGC 7142

Thanks for your findings - Cepheus is on my list !

andrew

[AndyWB]

That's a nice image of them - I couldn't resist rotating it to match what I saw:

Yup, that would put NGC7129 in the place I saw something. And I can't help but notice - ignoring magnitude, just looking at the image, NGC7129 is far more obvious than NGC7142. Maybe a surface brightness thing?