Abstract

Contributed Talk - Plenary

Introducing L-BASS: an instrument to tackle the ARCADE excess with absolutely calibrated observations at 1.4 GHz.

Phillip Black
University of Manchester

Based at the Jodrell Bank Observatory, the L-Band All-Sky Survey (L-BASS) aims to produce absolutely calibrated full-sky maps at 1.4 GHz with ≤ 0.1 K radiometric accuracy and 23° angular resolution. In phase 1, using twin conical horn antennas and a continuous-comparison receiver architecture similar to those employed by WMAP and Planck-LFI, L-BASS will measure the difference between a scanning beam and the North Celestial Pole. Phase 2 will establish the absolute zero level by replacing one horn with a cryogenic reference load. Accurate removal of diffuse Galactic emission remains a limiting factor in cosmic microwave and low-frequency astronomy. Absolutely calibrated maps from L-BASS will provide corrections to the temperature calibration of existing single-dish surveys (e.g. Haslam et al. @ 408 MHz and Reich et al. @ 1420 MHz) and help constrain the apparent isotropic radio background identified by ARCADE 2, which—if extragalactic—could represent a new photon field relevant to the thermal history of the early Universe.