Berkeley 29: the most distant open cluster

[Martin Meredith]

Lying way out in the opposite direction to the centre of our galaxy lies the faint open cluster Berkeley 29, believed to be the most distant cluster known (so far!) with a 2018 distance estimate of around 19k parsec (about 63000 light years), based on high-quality GAIA DR2 data [1]. Be 29 can be found in Gemini not too far from Alhena and a degree or so to the S of NGC 2304. The age is a matter of some debate. The estimate I've added to the inverted plot below of just over a billion years comes from the Dias open cluster catalogue, but other estimates [2] place it in the range 3-4 billion years old (a little younger than Messier 67).

These images were collected last night prior to moon-rise with Be 29 at a healthy 51 degrees above the horizon.

 

The colour image is 4 x 15s in each of RGB combined with 11 x 15s of L live at the scope in LAB. N is up in this image. No calibration was performed (except hot pixel removal).

Ref [2] gives magnitudes (typically 14.5-19.0) and colour indices for some of the cluster members but there appear to be much fainter stars in the background.

 

 

 

There are fainter stars I'm not capturing here in this relatively short exposure. This panel compares my shot (left) with the DSS image (centre) and a visualisation from the GAIA DR2 in which I'm plotting down to Gmag 21.

 

Martin

 

[1] http://simbad.u-strasbg.fr/simbad/sim-ref?bibcode=2018A%26A...618A..93C

[2] https://www.aanda.org/articles/aa/pdf/2005/03/aa1049.pdf

[Mike JW]

Hi Martin,

I am thoroughly enjoying your Berkeley adventures. I feel that at long last I am "seeing them". I wonder if any body has published a book of them (paper or online) - your approach would make for a very informative "publication". Keep having fun.  Mike

[Martin Meredith]

Thanks Mike. Me too! I have about another 14 to post in the main Berkeley thread at some point. I have about 40 to go but they're mainly in summer constellations (lots in Cygnus) so I will probably take a Berkeley break until then. Yes, I would like to compose a document at some point for these objects. In fact, I've already made such a thing for the GAIA visualisations of these clusters, which have helped enormously in identifying their locations in the first place.What I'd like to do is correct some of the cluster coordinates as quite a few appear to be wrong (by several arc minutes in some cases). I wish I had more time...

Martin