First USNO Robotic Astrometric Telescope Catalog

Longer integration times and more sensitive, backside CCDs allowed for a substantial increase in limiting magnitude, resulting in about 4-fold increase in the average number of stars per square degree as compared to UCAC. Additional observations with an objective grating largely extend the dynamic range to include observations of stars as bright as about 3rd magnitude.

Multiple sky overlaps per year result in a significant improvement in positional precision as compared to UCAC.