Flux Density Variation in VRO 42 22 01 at 1,420 M Hz

Abstract

SEVERAL recent papers1–3 have drawn attention to the interesting properties of the radio source VRO 42 22 01 and its optical counterpart BL Lac. In particular. Andrew et al.4 have reported the results of monitoring the intensity of this source at 6,630 and 10,630 MHz since December 1967, and point out particularly rapid changes in intensity at both frequencies. Seilstad and Yip5 found variations at 8,300 and 9,600 MHz, and also reported a flux density at 1,420 MHz measured in November 1968 of 4.2 flux units (1 flux unit = 10−26 W m−2 Hz−1), a value considerably below the 6.9 and 7.3 flux units reported for 1964 (ref. 6) and 1965 (ref. 7) respectively.