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

Ting Li, D. L. DePoy, R. Kessler, D. L. Burke, J. L. Marshall, J. Wise, J.-P. Rheault, D. W. Carona, S. Boada, T. Prochaska, R. Allen, Ian S. McLean (+2 others)
2012 Ground-based and Airborne Instrumentation for Astronomy IV  
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 enable photometric precision when coupled to more traditional techniques of less than 1% in photometric conditions. The system, aTmCam, consists of a set of
more » ... imagers each with a narrow-band filter that monitors the brightness of suitable standard stars. Each narrowband filter is selected to monitor a different wavelength region of the atmospheric transmission, including regions dominated by the precipitable water, aerosol optical depth, etc. We have built a prototype system to test the notion that an atmospheric model derived from a few color indices measurements can be an accurate representation of the true atmospheric transmission. We have measured the atmospheric transmission with both narrowband photometric measurements and spectroscopic measurements; we show that the narrowband imaging approach can predict the changes in the throughput of the atmosphere to better than ~10% across a broad wavelength range, so as to achieve photometric precision less than 0.01 mag. Downloaded From: on 01/30/2013 Terms of Use: * libRadTran is freely available at Proc. of SPIE Vol. 8446 84462L-2 Downloaded From: on 01/30/2013 Terms of Use: Proc. of SPIE Vol. 8446 84462L-3 Downloaded From: on 01/30/2013 Terms of Use: *
doi:10.1117/12.924792 fatcat:nwlpfrmzena63hug7ptrrr6fny