# title
aTmcam: A Simple Atmospheric Transmission Monitoring Camera For Sub 1% Photometric Precision

# abstract
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 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.  2012 SPIE.

# publicationOutlet
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY IV

# nameOfConference
Ground-based and Airborne Instrumentation for Astronomy IV

# publisher.label
SPIE, the international society for optics and photonics

# authorList[]
Li, T., Depoy, D. L., Kessler, R., Burke, D. L., Marshall, J. L., Wise, J., ... Allen, R.

# editorList[]
McLean, I. S., Ramsay, S. K., & Takami, H.