Steps Toward Determination of the Size and Structure of the
Broad-Line Region in Active Galactic Nuclei:
XIV. Intensive Optical Spectrophotometric Observations of NGC 7469
Collier, S., et al. 1998, ApJ, 500, 162
We present results of an intensive two-month campaign of ground-based spectrophotometric monitoring of the Seyfert 1 galaxy NGC 7469, with a temporal resolution less than about 1 day. The broad Halpha and Hbeta emission lines respond to ~35% ultraviolet continuum variations with and amplitude of ~10%, and time delays of 5.9 ± 1.3 days and 5.4 ± 0.8 days respectively. We interpret this as evidence of variable Balmer line gas ~5-6 light days from the central source in this object, widely believed to be a super-massive black hole. The virial mass of the central source implied by line widths and time delays is ~106-7 Msun. Concomitantly, we find evidence for wavelength-dependent continuum time delays: optical continuum variations lag those at 1315 Å by 1.1 ± 0.3 days at 4845 Å to 1.1 ± 0.7 days at 6962 Å. This suggests a stratified continuum reprocessing region extending several light days from the central source, possibly an accretion disc.