PROPER MOTION OF QUASARS

A Result from VLBI

Shapiro et al. (1979) have used very-long-baseline interferometry to obtain some evidence on the relative proper motion of two quasars, 3C 345 and NRAO 512. These two quasars are separated by half a degree, and were observed repeatedly with very-long-baseline interferometers over a period of four years. These two sources have approximately the same right ascension as the galactic center. No relative proper motion in declination was detected with the upper bound being under 0.0002 arcsec/yr. this result is fully consistent with our expectations. We note that the measured value gives the relative value of only the declination component of the proper motion, which for one particular pair could even be zero. More such studies would be highly desirable.

Next Section: Interstellar K & H lines as distance indicators.