Optical sky brightness at Dome A, Antarctica, from the Nigel experiment

Abstract

Nigel is a fiber-fed UV/visible grating spectrograph with a thermoelectrically-cooled 256 1024 pixel CCD camera, designed to measure the twilight and night sky brightness from 300 nm to 850 nm. Nigel has three pairs of fibers, each with a field-of-view with an angular diameter of 25 degrees, pointing in three fixed positions towards the sky. The bare fibers are exposed to the sky with no additional optics. The instrument was deployed at Dome A, Antarctica in January 2009 as part of the PLATO (PLATeau Observatory) robotic observatory. During the 2009 winter, Nigel made approximately six months of continuous observations of the sky, with typically 103 deadtime between exposures. The resulting spectra provide quantitative information on the sky brightness, the auroral contribution, and the water vapour content of the atmosphere. We present details of the design, construction and calibration of the Nigel spectrometer, as well some sample spectra from a preliminary analysis.

Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

“…The extremely large FOV of the GASC allows us to monitor the night sky brightness in the B, V, and R photometric bands and the cloud cover beginning in the 2009 winter season at Dome A over a wide range of zenith angles (  0 to~ 30 ). Multiband sky intensities measured by GASC in combination with spectra obtained with the NIGEL instrument (Sims et al 2010) will offer more comprehensive statistics on aurora and airglow. In addition, photometry of bright target stars in the GASC FOV with an unprecedented temporal window function is permitted by months of continual darkness during the Antarctic winter.…”