AAVSO: American Association of Variable Star Observers

Proposal #106

Proposer (4406) Michael Richmond (mwrsps@rit.edu) obscode: RHM
Assigned To(3663) Dirk Terrell
Date SubmittedJan. 26, 2019

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

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

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
NGC 6418 17.635917 58.71472 14.5–15.5 No


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