Per Collinder [SEP] date of birth
Per Collinder
Per Collinder (22 May 1890 – 6 December 1974) was a Swedish astronomer. 
Born at Sundsvall, he is known for a catalog of open clusters that he published in 1931, which is today known as the Collinder catalog. He has written the books "History of navigation" and "Worlds in Orbit".
He was married twice, and his first wife gave him four children. Collinder died at Uppsala.
Collinder catalog
In astronomy, the Collinder catalog is a catalog of 471 open clusters by Swedish astronomer Per Collinder. It was published in 1931 as an appendix to Collinder's paper "On structural properties of open galactic clusters and their spatial distribution". Catalog objects are denoted by "Collinder", e.g. "Collinder 399". Dated prefixes include as "Col + catalog number", or "Cr + catalog number", e.g. "Cr 399".
Notable objects.
Some notable objects from the catalog are