Proposal #106

NGC 6418 is an AGN which our group has studied for seven years, combining observations in the optical and IR to measure the reverberation lag; a careful analysis of the lag can reveal the size and structure of the dusty torus around the central engine (Vazquez et al. 2015; Almeyda et al. 2017). After several small and one large nuclear outburst in 2013-2015, the galaxy has remained in a quiescent state for the past few years. If we can detect the next outburst at an early stage, we can trigger Target-of-Opportunity observations with X-ray telescopes in space and spectroscopic programs with ground-based telescopes.

We request weekly monitoring of the galaxy in two passbands; one should be R or r, the other B or g. Either the SRO50 or TMO61 should work well, but we would prefer the TMO61 for its higher resolution: we will try to separate the nuclear light from as much of the surrounding starlight as possible. Exposure times of 2x60 seconds in r and 2x90 seconds in g should provide S/N of order 100, which is sufficient for our purposes. We will perform our own photometry on the images, since the source is non-stellar.

Filters: g and r (TMO61), B and R (SRO50)
Cadence: weekly between Jan 20 and Nov 15

References:
Almeyda et al., ApJ 843, 3 (2017)
Vazquez et al., ApJ 801, 127 (2015)