Di Li(National Astronomical Observatories of China)
Inspired by the visionary efforts of building Arecibo, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) was proposed first as part of a SKA concept and formally established as a stand-alone project in 2007. Through much trials and tribulation, FAST started its normal operation in 2020 as the largest antenna in the world. We have released the first internationally open call-for-proposal in March 2021. I report here a few science highlights so far, particularly from the Commensal Radio Astronomy FAST Survey (CRAFTS). Enabled by a novel calibration technique, CRAFTS simultaneously records pulsar, Galactic HI, extra-galactic HI, and transient data streams and is thus the first such commensal survey worldwide. CRAFTS has discovered more than 150 new pulsars, including more than 40 milli-second pulsars at least one double-neutron star system. We have imaged about 5% of the full sky, including the Lockman hole, the Orion region, etc. CRAFTS has also resulted in 6 new FRBs, including one high DM repeater that has been localized. Other dedicated programs have also produced significant results, such as the first detection of Zeeman effect through HI narrow self-absorption (HINSA), the most stringent flux limit of the first Galactic FRB source that was selected as part of the top 10 scientific achievements for the year 2020 by both the 《Nature》and 《Science》magazine, etc. Possibly the last giant single dish of its kind, FAST has started to realize its aspiration in exploring a unique parameter space of the cosmos.