Evaluating the temperature of the sky: The L-Band All-Sky Survey

The L-Band All Sky Survey (L-BASS) will map the intensity of the radio sky at 1.4\,GHz with an unprecedented absolute accuracy (0.1 K), ten times better than in the observations which discovered the Cosmic Microwave Background. The unique L-BASS sky map will have an impact on Galactic astrophysics, on our knowledge of the Cosmic Microwave Background and will settle a current astrophysical puzzle about the reality of excess low frequency emission of unknown origin (the 'ARCADE-2 controversy'). Achieving these goals requires the development of specialised radio astronomical instrumentation and an innovative software pipeline for the real-time data and its analysis. The first phase of the project, L-BASS North, will be carried out at Jodrell Bank. In the future it is planned to take data in the Southern hemisphere.

Radio maps made with large parabolic dishes inevitably suffer from significant zero-level offsets and position-varying calibration errors because of ground pick-up via sidelobes; these corruptions limit their astrophysical impact. To minimise such problems L-BASS will use a pair of purpose-built horn antennas. Over the course of the project the PhD student, working with experienced radio astronomers, will obtain a broad training in: i) state-of-the-art radio astronomy techniques from involvement in commissioning the hardware (antennas, receivers, cryogenic calibrators), and developing and using the data analysis pipeline; ii) knowledge of a broad range of Galactic and CMB-related astrophysics. The student will be involved in finding the southern-hemisphere observing site. A series of interpretation papers will result from this phase of the project over and above ones describing the instrument, the data analysis and the northern hemisphere map. These include descriptions of foreground component separation and impacts on Galactic science, CMB science and the ARCADE2 controversy. And as by-products: i) a low resolution absolutely calibrated map of Galactic neutral hydrogen; ii) the absolute brightness temperature of the Moon at 1.4 GHz