A new proper motion catalog is presented , combining the Sloan Digital Sky Survey ( SDSS ) with second epoch observations in the r band within a portion of the SDSS imaging footprint .
The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope , and the Array Camera on the U.S .
Naval Observatory , Flagstaff Station , 1.3 meter telescope .
The catalog covers 1098 square degrees to r = 22.0 , an additional 1521 square degrees to r = 20.9 , plus a further 488 square degrees of lesser quality data .
Statistical errors in the proper motions range from 5 mas year ^ { -1 }  at the bright end to 15 mas year ^ { -1 }  at the faint end , for a typical epoch difference of 6 years .
Systematic errors are estimated to be roughly 1 mas year ^ { -1 }  for the Array Camera data , and as much as 2 – 4 mas year ^ { -1 }  for the 90prime data ( though typically less ) .
The catalog also includes a second epoch of r band photometry .