The time and frequency standard system for FAST receivers

This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The stability and drift rate of the frequency standard are calculated using 1-year monitoring data.The UTC-NIM Disciplined Oscillator(NIMDO)system improves the system time accuracy and stability to the level of 5 ns.Pulsar timing observations were carried out for several months.The weighted RMS of timing residuals reaches the level of less than 3.0μs.

Opportunities to search for extraterrestrial intelligence with the FAST

The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intelligence(SETI).Large scale SETI activities are now underway at numerous international facilities.The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-aperture radio telescope in the world,and is well positioned to conduct sensitive searches for radio emission indicative of exo-intelligence.SETI is one of the five key science goals specified in the original FAST project plan.A collaboration with the Breakthrough Listen Initiative was initiated in 2016 with a joint statement signed both by Dr.Jun Yan,the then director of National Astronomical Observatories,Chinese Academy of Sciences(NAOC),and Dr.Peter Worden,Chairman of the Breakthrough Prize Foundation.In this paper,we highlight some of the unique features of FAST that will allow for novel SETI observations.We identify and describe three different signal types indicative of a technological source,namely,narrow band,wide-band artificially dispersed and modulated signals.Here,we propose observations with FAST to achieve sensitivities never before explored.For nearby exoplanets,such as TESS targets,FAST will be sensitive to an EIRP of 1.9×1011 W,well within the reach of current human technology.For the Andromeda Galaxy,FAST will be able to detect any Kardashev type II or more advanced civilization there.

FAST VLBI: current status and future plans

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-dish radio telescope in the world,and is now being commissioned after the first light in September 2016.Very long baseline interferometry(VLBI)is among the key science topics according to the original design.The FAST VLBI system has been established,and the first VLBI fringe has been successfully obtained.FAST will significantly improve the sensitivity of the existing VLBI networks in the future,and some science projects in need of high sensitivity will benefit from its participation.

Dish Verification Antenna China for the SKA:design, verification and status

The Square Kilometre Array(SKA) will be the world’s largest synthesis radio telescope, which is designed to answer major scientific questions such as those relating to the cosmic origin and fundamental forces in the universe. With the SKA entering into the phase of pre-construction, more than 100 institutes in about 20 countries including China have been involved in the associated key technology development.The Dish Verification Antenna China(DVA-C) is a concept prototype which has been built to meet the requirements of the SKA’s scientific goals. It utilizes a unique skin-and-rib structure with single-piece panel reflectors. This paper presents details on the design and measured performances of DVA-C, as well as the preliminary observational results. Current applications of the DVA-C are also introduced.

An optimization of the shape of FAST reflector panels

The Five-hundred-meter Aperture Spherical radio Telescope （FAST） will be the largest radio telescope in the world. The surface tolerance of the main reflector is one of the most important parameters for evaluating the performance of the telescope. The relationship between the reflector＇s surface tolerance and the curvature of FAST reflector panels is analyzed and discussed. According to the calculation of reflector tolerance and antenna gain, an optimized panel shape for minimum surface tolerance and maximum gain is derived. The far field pattern of the FAST telescope is presented while the optimized shape is utilized for reflector panels. The results show that FAST could be operated at a frequency band of 8 GHz or even higher with an acceptable efficiency.