  Light variation of the 47 AGB star candidates in the outer Galactic disk has
been monitored at I-band for 5 years. Periods were determined well for 18 of
them and less reliably for the other 25. The average period of the objects is
then 500 days. According to the period-luminosity relation, the mean luminosity
of the sample stars is 10000 $\LO$. Based on the absolute luminosity derived
from the period-luminosity relation and the apparent luminosity from the
observation, the distances to the objects are determined. The distances
calculated are slightly greater than those obtained previously on the
assumption of constant luminosity of 8000 $\LO$. In addition, SiO maser
emission was detected for most of the observed objects so that their radial
velocities were known accurately. With the assumption of circular rotation in
the Galactic disk, the rotation curve and Oort's constants were derived.
