Science of Synthesis: Cross Coupling and Heck-Type Reactions 3, Metal-Catalyzed Heck-Type Reactions and C–C Cross-Coupling via C–H Activation

Abstract

We present results of a five month spectroscopic monitoring campaign of the Seyfert-1 galaxy NGC 3516. Using a new calibration method and applying a correction for seeing differences during the various observations we can scale the spectra to each other with a much higher accuracy than hitherto achieved. NGC 3516 shows large amplitude variations on a time scale of several weeks. Asymmetric profile variations occur on the same time scale as the continuum variations. We show the presence of a varying dip on the blue wing of the H-beta profile, which is not present on the H-alpha profile, and which corresponds to the absorption features previously seen in the UV emission lines of NGC 3516. From cross-correlation analysis we find a time lag of 14 +/- 2 days for the H-alpha and 7 +/- 3 days for the H-beta emission-line response to continuum variations.