Studies of atmospheric noise on Mauna Kea at 143 GHz with Bolocam

Abstract

We report measurements of the fluctuations in atmospheric emission (atmospheric noise) above Mauna Kea recorded with Bolocam at 143 GHz. These data were collected in November and December of 2003 with Bolocam mounted on the Caltech Submillimeter Observatory (CSO), and span approximately 40 nights. Below s 0.5 Hz, the data time-streams are dominated by the f -δ atmospheric noise in all observing conditions. We were able to successfully model the atmospheric fluctuations using a Kolmogorov-Taylor turbulence model for a thin wind-driven screen in approximately half of our data. Based on this modeling, we developed several algorithms to remove the atmospheric noise, and the best results were achieved when we described the fluctuations using a low-order polynomial in detector position over the 8 arcminute focal plane. However, even with these algorithms, we were not able to reach photon-background-limited instrument photometer (BLIP) performance at frequencies below s 0.5 Hz in any observing conditions. Therefore, we conclude that BLIP performance is not possible from the CSO below s 0.5 Hz for broadband 150 GHz receivers with subtraction of a spatial atmospheric template on scales of several arcminutes.