839 Valborg is a mid-sized S-type Eunomian asteroid. Its diameter is about 20 km, its albedo of 0.353 is very high for an asteroid<sup>https://archive.today/20060623213811/http://www.psi.edu/pds/archive/astdata04/simps04/diamalb.tab</sup>. Its rotation period is 10.366 hours<sup>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2006MPBu...33...39W&db_key=AST&data_type=HTML&format=&high=444b66a47d26580</sup>.