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 ≃ 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 ≃ 0.5 Hz in any observing conditions. Therefore, we conclude that BLIP performance is not possible from
the CSO below ≃ 0.5 Hz for broadband 150 GHz receivers with subtraction of a spatial atmospheric template
on scales of several arcminutes.
Bolocam is a millimetre-wave (1.1 and 2.1 mm) camera with an array of 119 bolometers. It has been commissioned at the Caltech Submillimeter Observatory in Hawaii and is now in routine operation. Here we give an overview of the instrument and the data reduction pipeline. We discuss models of the sensitivity of Bolocam in different observing modes and under different atmospheric conditions. We briefly discuss observations of star-forming Galactic molecular clouds, a blank field survey for sub-millimeter galaxies, preliminary results of a blank-field CMB secondary anisotropy survey and discuss observations of galaxy clusters using the Sunyaev-Zel'dovich effect.
We describe the design and performance of Bolocam, a 144-element, bolometric, millimeter-wave camera. Bolocam is currently in its commissioning stage at the Caltech Submillimeter Observatory. We compare the instrument performance measured at the telescope with a detailed sensitivity model, discuss the factors limiting the current sensitivity, and describe our plans for future improvements intended to increase the mapping speed.