FAST FRB backend; LQ, GH, XYX, QJZ, SD made key contributions to the overall FAST data processing pipelines; LS, MC, MK provided salient information on FRB 121102 from other observatories, particularly Effelsberg, and contributed to the scientific analysis; SC, JMC, DRL made numerous corrections to the writing and analysis. JMC, in particular, pointed out the errors in the noise floor analysis in the original draft. * Uncertainties in parentheses refer to the last quoted digit. † Reduced χ 2 is obtained by the best fitting method with 20 iterations. ‡ Coefficient of determination, R 2 = 1 − S res /S tot , where S tot is total sum of squares from data, and S res is the minimum fitting residual sum of squares.

No abstract

Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas as it forms along with H 2 under similar conditions and within a similar extinction range. We have analyzed absorption measurements of OH at 1665 MHz and 1667 MHz toward 44 extragalactic continuum sources, together with the J=1-0 transitions of 12 CO, 13 CO, and C 18 O, and the J=2-1 of 12 CO. The excitation temperature of OH were found to follow a modified log-normal distribution

The Five‐hundred‐meter Aperture Spherical Radio Telescope (FAST) is a Chinese megascience project funded by the National Development and Reform Commission (NDRC) of the People's Republic of China. The National Astronomical Observatories of China (NAOC) is in charge of its construction and subsequent operation. Upon its expected completion in September 2016, FAST will surpass the 305 m Arecibo Telescope and the 100 m Green Bank Telescope in terms of absolute sensitivity in the 70 MHz to 3 GHz bands. In this paper, we report on the project, its current status, the key science goals, and plans for early science.