Multifrequency Observations of the Optically Active Radio-quiet Quasar GQ Comae. I. Ultraviolet Continuum and Line Variability

Abstract

This paper summarizes the data and preliminary results of a 3 year project to monitor the continuum variability of GQ Com in the satellite ultraviolet and the associated variability of the Lyα and C IV lines. Simultaneous and nearly simultaneous ground-based optical and infrared data were also obtained, but these will be discussed more fully in a future paper. GQ Com exhibited a twofold increase in flux during a 100 day time span, followed by a decline taking over 3 times longer. The broad wings of C IV responded quickly to the continuum increase, although the coarseness of the time resolution allows only an upper limit of 50 days to be placed on any time delay between the continuum and the line wings. The response of the wings of Lyα are not as well defined. In contrast, the cores of both lines lagged the continuum by at least 50-100 days. During the course of the observations, the Lyα line profile underwent considerable changes in shape. The profile changes were also seen in C IV on one occasion. These changes occurred while the continuum was in a low state. The data indicate considerable structure may be present in the broad-line region.