Confusion errors in astrometry and counterpart association

摘要: In very crowded fields, the modulation of background by sea unresolved faint sources induces centroid shifts. The errors increase with number per beam. Even most optimistic simulations imaging data show that position can become severe (on order beam size) at flux levels which images contain 1/50 to 1/15 beam, depending on slope number-flux relation d log N/d S. These problems are expected be significant for recent observations submillimeter and may reason some appear lack optical counterparts.