This covers several ways of estimating the distance to an object based on the classification of the object and knowing that a typical object of that type (e.g. a Brown Dwarf) has a typical absolute flux density. You estimate the distance by comparing the apparent flux density (or optical magnitude etc.) with the typical absolute flux density if that object was at a standard distance e.g. 10 pc.

-- AnitaRichards - 24 Apr 2003