Intraday Variable Sources Research Articles

VLBI Observations of Intraday Variability

AbstractIntegrated VLA measurements during our 6 cm global VLBI polarization observations of the intraday variable sources 0716+714, 0917+624, and 0954+658 indicate that although there were no significant total intensity variations during the 24-hour VLBI experiment, the polarization for all three sources varied substantially. Independent polarization images made for 2–3 hour segments show that there were no variations on VLBI scales for 0716+714 or 0954+658, but that there were appreciable variations in the VLBI core of 0917+624, which correlate well with the integrated variations in the simultaneous VLA data.

VLBI polarization observations of intraday variability

Global λ6 cm VLBI polarization observations of the intraday variable sources 0716+714, 0917+624, and 0954+658 are analyzed. Integrated VLA measurements during the VLBI observations suggest that although there were no substantial total intensity variations, the polarization for all three sources varied significantly during the 24 h VLBI experiment. The VLBI data were divided into 2–3 h segments in order to identify corresponding rapid variability in the VLBI structure. There is evidence that the polarization variability indicated by the VLA measurements of 0917+624 is present in the VLBI data (i.e. it occurred on mas scales), but this is not the case for the other two sources.