aTmcam: a simple atmospheric transmission monitoring camera for sub 1 photometric precision

摘要

Traditional color and airmass corrections can typically achieve ~0.02 mag precision in photometric observing conditions.A major limiting factor is the variability in atmospheric throughput, which changes on timescales of less than a night.We present preliminary results for a system to monitor the throughput of the atmosphere, which should enablephotometric precision when coupled to more traditional techniques of less than 1% in photometric conditions. Thesystem, aTmCam, consists of a set of imagers each with a narrow-band filter that monitors the brightness of suitablestandard stars. Each narrowband filter is selected to monitor a different wavelength region of the atmospherictransmission, including regions dominated by the precipitable water, aerosol optical depth, etc. We have built aprototype system to test the notion that an atmospheric model derived from a few color indices measurements can be anaccurate representation of the true atmospheric transmission. We have measured the atmospheric transmission with bothnarrowband photometric measurements and spectroscopic measurements; we show that the narrowband imagingapproach can predict the changes in the throughput of the atmosphere to better than ~10% across a broad wavelengthrange, so as to achieve photometric precision less than 0.01 mag.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.