The fourth U.S. Naval Observatory CCD Astrograph Catalog (UCAC4)

UCAC4 is a compiled, all-sky star catalog covering mainly the 8 to 16 magnitude range in a single bandpass between V and R. Positional errors are about 15 to 20 mas for stars in...

UCAC4 是一份汇编完成的全天星表，采用介于V波段与R波段之间的单一观测通带，主要覆盖8至16等的恒星。对于……中的恒星，其位置误差约为15至20毫角秒（mas）。