Some summer Berkeley clusters

[Martin Meredith]

Its been a while since I had the scope out and what with a near dead battery and software teething problems I was very lucky to be able to view 7 further Berkeley clusters in a 45 minute session between dusk and the rising of the near-full moon. I'm making a few changes to the code so the annotation isn't perfect (ignore the SQM reading) and I seem to have omitted the constellation codes -- Be 52 is in Vul, Be 44 in Sagitta and the remaining 5 are in Aquila. 

Most of the Berkeley clusters I've observed so far can best be described as faint but with a certain shimmering density of stars -- rather like Messier 41 appears in 10x50s, or perhaps Messier 46 rather than its neighbour M47. Most of the clusters from last night fit that description, but Be 82 is a real exception (assuming I've got the correct location!) -- sparse and bright (and beautiful, I think). Possibly the most challenging was Be 52 which needed a bit more of a stretch than I would normally use for clusters.

These are all live-combined LRGB captures using 15s subs; generally with 1 minute's worth in each but sometimes with added L. No calibration (just hot pixel removal). Colour manipulations (at the scope) limited to saturation and colour stretch, but generally these were left at default settings. North is at the top.

Thanks for looking!

Martin

 

 

 

[Mike JW]

Hi Martin, I had been wondering when you might continue the Berkeley journey. Great to see some more and in colour. As you indicate some of them really do take a bit of convincing that they are clusters. Agree re Be 82 - wins the pretty cluster award for the outing.

Mike

[Martin Meredith]

Thanks Mike. I hope to continue tonight since the moon will hold off for a little longer. It is predicted to be 31C at 10pm though so I might invest in some darks...

For identification I use charts that I've constructed from the GAIA data (happy to share if anyone wants them) which make things a little easier, but alignment needs to be quite close for a small sensor like the Lodestar. In constructing these charts I've seen that the official RA/Dec for the Berkeleys are not accurate in quite a few cases. Once I complete the journey (I'm currently about 2/3 through) I'll put together some resources and try to estimate better coordinates.

I must admit that I really like these faint clusters and when I occasionally happen upon say a Messier cluster it somehow appears bright and vulgar in comparison 😉.  Not sure what OCs to look at next but perhaps the Ruprecht catalogue, although a great many are not visible here. Having said that, I've still not observed most of the NGC/IC clusters... so many interesting objects, so little time...

Martin

[Martin Meredith]

I finally managed to complete my observations of the Berkeley open clusters on Sunday. Now comes the job of assembling them all into something coherent.... I feel some automation is needed. 

Meanwhile, the most interesting of the last batch (of 4) was Berkeley 55 in Cygnus.

This is a compact, highly-reddened cluster located about 4 kpc away in the Perseus Arm, and which is estimated to be pretty young (~50Myr). The most interesting feature is the obvious cluster of bright red stars.

This paper https://arxiv.org/pdf/1112.0414.pdf looks at the cluster in detail with optical and spectroscopic observations from La Palma, and identifies the 6 or 7 red (super)giants clearly visible in the image.

 

 

Out of interest, I created some finder charts using GAIA stellar data during the Berkeley campaign as some of them are quite hard to spot. Here's the one for Be 55. It is pretty remarkable how similar it is, and slightly depressing too, as it somewhat ruins the surprise.... 

 

cheers

Martin

 

[Mike JW]

Congratulations on completing the tour - well worth it.

Mike