Collinder objects observed from my observatory

Dr Per Collinder . the historian of the development of astronomy in Sweden died in December 1975. Although a student of stars in the galactic clusters, his professional life was spent in surveying the sea’s around Sweden and in the Arctic.

In 1931 he became a Ph.D. in astronomy at Lund University with his dissertation

‘On Structural Properties of Open Clusters and Their Spatial Distribution’. Collinder was trying to gain and insight into the structure of the Milky way Galaxy by determining how open clusters were distributed and seeing whether the majority of them populated the galactic plane. This proved true and as a result, Collinder’s catalogue reflects that distribution.

The catalogue was resurrected by historian Nancy Thomas, from a copy of Collinder’s original dissertation found in the archives of the US Naval Observatory. The catalogue data was then corrected on further research by Thomas Watson, who says of his final list.

As I was working my way through the process of making the conversion, a chance came my way, in the summer of 2006, to see Collinder’s dissertation in its entirety. A spur of the moment search with Google Scholar, followed up by a call to the folks at the University of Arizona interlibrary loan program, put a copy of the seventy-five year old tome in my hands for a few weeks. It was an interesting read, written as it was in a more personable and human style than we see used in professional science journals and dissertations these days. Of greatest interest was the collection of notes that followed the catalog, in which Collinder discusses the individual objects he decided to include in his research. Holding that old dissertation in my hands, after trying for so long to find out anything at all about its author, was a very satisfying experience. The search had come full circle.

Most of the clusters in the Collinder Catalog are objects suited to telescopes of various sizes. Some require high magnification, others a low power wide field eyepiece. Some are best viewed with binoculars, or even with the naked eye. If nothing else, Collinder’s catalog clearly illustrates that open star clusters represent a highly diverse set of deep sky objects.

With 27.4% of the catalogue never rising above the horizon from here, this is one observing programme I’m never going to be able to complete – unless I travel further South 🙁

Objects that I have made at least one observation is given in the ‘Observations’ column.