Observing low elevation sky and the CMB Cold Spot with BICEP3 at the South Pole
astro-ph.CO
/ Authors
J. Kang, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, J. J. Bock, H. Boenish, E. Bullock
and 77 more authors
V. Buza, J. R. Cheshire, J. Connors, J. Cornelison, M. Crumrine, A. Cukierman, E. Denison, M. Dierickx, L. Duband, M. Eiben, S. Fatigoni, J. P. Filippini, S. Fliescher, N. Goeckner-Wald, D. C. Goldfinger, J. A. Grayson, P. Grimes, G. Hall, M. Halpern, S. A. Harrison, S. Henderson, S. R. Hildebrandt, G. C. Hilton,
/ Abstract
BICEP3 is a 520 mm aperture on-axis refracting telescope at the South Pole, which observes the polarization of the cosmic microwave background (CMB) at 95 GHz to search for the B-mode signal from inflationary gravitational waves. In addition to this main target, we have developed a low-elevation observation strategy to extend coverage of the Southern sky at the South Pole, where BICEP3 can quickly achieve degree-scale E-mode measurements over a large area. An interesting E-mode measurement is probing a potential polarization anomaly around the CMB Cold Spot. During the austral summer seasons of 2018-19 and 2019-20, BICEP3 observed the sky with a flat mirror to redirect the beams to various low elevation ranges. The preliminary data analysis shows degree-scale E-modes measured with high signal-to-noise ratio.