FAST Radio Telescope

FAST is the largest single-dish radio telescope in the world and has found more than 1,300 pulsars

The Five-hundred-meter Aperture Spherical radio Telescope (FAST), called the Sky Eye (Tianyan) in China, observes from 70 MHz to 3 GHz with about 2.5 to 3 times the sensitivity of Arecibo. It sees the sky up to 40 degrees from the zenith, with an upgrade planned to more than 50. Its science areas are pulsars, neutral hydrogen galaxies, fast radio bursts (FRBs) and gravitational waves.

In its first decade FAST found more than 1,300 pulsars, more than all other telescopes combined over the same period, with 13 papers in Science and Nature. Its neutral hydrogen survey has charted 156,000 galaxies over nearly half the sky. In 2025 it reported an eclipsing millisecond pulsar, and in January 2026 a change in the Faraday rotation of a repeating FRB that supports a binary origin. It joined the Breakthrough Listen search for extraterrestrial intelligence (SETI) in October 2016.

The National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) operates FAST; its chief engineer is Jiang Peng. Nan Rendong proposed the telescope in 1994. Ground was broken on 26 December 2008, the telescope was completed on 25 September 2016, its first pulsar discovery was announced on 10 October 2017, and it passed national acceptance and began full operation in January 2020. It cost CNY 1.2 billion (about US$180 million), opened to international users in August 2021, and won the first prize of the 2025 National Science and Technology Progress Award, announced 8 July 2026.

FAST fills the Dawodang karst depression near Kedu town, Pingtang County, in the Qiannan Buyei and Miao Autonomous Prefecture of Guizhou, at about 1,000 m. The 9,110 residents within 5 km were relocated, along with a village of 65 people from the valley itself. See the FAST listing, radio telescopes around the world, the largest radio telescopes and more observatories in China.

FAST reshapes its 500-meter reflector as it tracks, with 2,225 actuators under the cable net

The 500 m reflector is a cable net of about 7,000 steel cables and 2,300 nodes hung from a steel ring beam and covered by 4,450 triangular aluminum panels about 11 m on a side. Under the nodes, 2,225 actuators, each a stepper-motor-driven hydraulic unit, pull the net into shape beneath a 300 m illuminated aperture with a focal length of 140 m.

Liuzhou OVM Machinery made the cable net and tensioned it to high precision with the prestressing team of Southeast University, led by Guo Zhengxing from 2011, which worked out the construction analysis and assembly method. The net flexes every time the telescope repoints, so its cables were specified for a stress amplitude of 500 MPa over two million cycles, 2.5 times the standard.

Siemens S7-300 PLCs, 12 sets in 12 relay rooms, control the actuators, about 185 per room, over PROFIBUS-DP and fiber. The makers of the panels and the original actuators are not publicly named. The actuators were among the imported parts now made in China; the domestic maker is not publicly named either.

Component	Supplier	Country	Role	Status	Note
Reflector cable net manufacture and high-precision tensioning	Liuzhou OVM Machinery	China	Manufacturer	In service	With Southeast University prestressing team
Cable net construction analysis and assembly method	Southeast University	China	Designer	In service	Team led by Guo Zhengxing from 2011
4,450 triangular aluminum reflector panels	Not publicly named	-	Manufacturer	In service	About 11 m per side
2,225 stepper-motor-driven hydraulic actuators	Not publicly named	-	Manufacturer	In service	One per cable-net node; originally imported
Domestic replacement actuators	Not publicly named	China	Manufacturer	In service	Localized after a decade of operation
PLCs controlling 2,225 reflector actuators	Siemens	Germany	Manufacturer	In service	12 S7-300 PLC sets over PROFIBUS-DP

Six cables from six towers fly a 30-metric-ton feed cabin 140 meters above the dish

FAST has no fixed structure at its focus. The receivers ride in a 30-metric-ton feed cabin towed by six cables from six towers, a cable-driven parallel robot that moves the cabin 140 m above the reflector across a space 206 m wide. Inside the cabin, an AB rotator and a Stewart platform refine the position. Dalian Heavy Industry built the six cable-drive mechanisms under an EPC contract signed on 30 June 2012. Total stations, GNSS, an inertial measurement unit (IMU) and microwave ranging are fused to track where the cabin is.

On 15 June 2026 FAST installed six domestically made feed-support cables, at about half the cost of the foreign cables they replace. Laser total stations are now made in China too. The makers of both are not publicly named. A planned replacement, a six-cable parallel robot, would carry more than four metric tons of spare payload.

Component	Supplier	Country	Role	Status	Note
Feed cable-drive system, six cable-drive mechanisms (EPC)	Dalian Heavy Industry	China	Manufacturer	In service	EPC contract 30 Jun 2012; moves the 30 t feed cabin
Six domestic feed-support steel cables, installed 15 Jun 2026	Not publicly named	China	Manufacturer	In service	About half the cost of the imported cables
Domestic laser total stations for feed cabin measurement	Not publicly named	China	Manufacturer	In service	Replace previously imported units

An Australian-built 19-beam receiver watches 19 patches of sky at once

CSIRO Astronomy and Space Science designed and built the 19-beam L-band receiver (FLAN), covering 1.05 to 1.45 GHz, with its feeds, orthomode transducers (OMTs) and low-noise amplifiers (LNAs) made in-house. It is cryogenic, with a system temperature under 24 K near 1.4 GHz and an aperture efficiency of about 0.63. An ultra-wideband receiver covers 500 to 3,300 MHz in four bands, at a system temperature of about 88 to 130 K. Low-noise amplifiers are among the parts now made in China; the domestic maker is not publicly named.

The maker of the hydrogen maser that keeps time at FAST is not publicly named.

Component	Supplier	Country	Role	Status	Note
19-beam L-band cryogenic receiver, 1.05-1.45 GHz	CSIRO Astronomy and Space Science	Australia	Manufacturer	In service	Designed and built feeds, OMTs and LNAs in-house
Domestic low-noise amplifiers	Not publicly named	China	Manufacturer	In service	Replace previously imported units
Hydrogen maser time standard	Not publicly named	-	Manufacturer	In service	Maker not named in public sources

FAST's 19 beams pour out 38 gigabytes a second before compression

The 19-beam receiver delivers about 38 GB/s of raw data. ROACH2 boards, an open-source FPGA design from the CASPER collaboration, channelize the signal on board, and a first stage of compression brings it down to about 6.3 GB/s, 544 TB a day, over 100 Gigabit Ethernet. The yearly total is about 20 PB, with 7 to 10 PB a year planned for pulsar storage. The Commensal Radio Astronomy FAST Survey (CRAFTS) runs four backends at once: pulsar search, neutral hydrogen imaging, neutral hydrogen galaxies and transients.

On site in Kedu town, Inspur AS13000G5 distributed storage gives a 30 PB usable astronomical data platform. A FAST data center agreed in Gui'an New District targets 100 PB of storage and 1,000 TFLOPS over a decade, at a cost of CNY 160 million on 40,000 square meters. The archive runs the Next Generation Archive System (NGAS), software from ICRAR in Australia and ESO.

Component	Supplier	Country	Role	Status	Note
ROACH2 digital back ends	CASPER collaboration	US	Designer	In service	Open-source FPGA board design used for FAST backends
30 PB usable on-site storage platform (AS13000G5)	Inspur	China	Manufacturer	In service	Distributed storage at Kedu town
FAST data center, Gui'an New District	NAOC	China	Operator	Planned	Targets 100 PB and 1,000 TFLOPS over a decade
Next Generation Archive System (NGAS) archive software	ICRAR	Australia	Designer	In service	Co-developed with ESO
Next Generation Archive System (NGAS) archive software	ESO	Germany	Designer	In service	Co-developed with ICRAR

Deep learning built for FAST sorts more than 1.6 million pulsar candidates a day

Beijing Normal University built the PICS-ResNet ensemble for the FAST drift-scan survey: a 15-layer residual network that reads the 2D diagnostic plots of each candidate, plus a support vector machine (SVM) for the 1D plots. It classifies more than 1.6 million candidates a day on a dual-GPU machine with 98% recall on FAST test candidates. Its operational use in CRAFTS is not explicitly confirmed.

CRAFTS does use a GPU single-pulse search pipeline (GSP) with a database, and a 2023 study applies hybrid clustering across several data types to sift FAST survey candidates.

Component	Supplier	Country	Role	Status	Note
PICS-ResNet pulsar candidate classifier	Beijing Normal University	China	Designer	Delivered	Built for CRAFTS drift scan; operational use not confirmed

The FAST Core Array will ring the big dish with 24 antennas of 40 meters

Phase II of FAST, the Core Array, adds 24 antennas of 40 m within 5 km of the dish, with a maximum baseline of about 10 km, a range of 0.35 to 10 GHz and a resolution of about 4.3 arcseconds at 1.4 GHz. Construction officially began on 25 September 2024; six antennas are planned by 2026 and the full array by 2030. With the 500 m dish at its center, it is described as the first hybrid-aperture interferometer.

Component	Supplier	Country	Role	Status	Note
FAST Core Array, 24 x 40 m antennas	NAOC	China	Operator	Planned	Six antennas by 2026, full array by 2030

Visitors see FAST from platforms above the dish and leave their phones behind

Public visits center on Pingtang Astronomy Town. Viewing platforms look over the dish, but there is no access to the reflector. The town also has the Astronomy Experience Hall, with VR and AR exhibits, and the Nan Rendong Memorial Hall. Phones, digital cameras and smartwatches are banned inside the 5 km core zone; there is device storage, and film cameras can be rented.

A radio quiet zone regulation from April 2019 sets a core zone of 5 km, an intermediate zone from 5 to 10 km and an external zone from 10 to 30 km. Unapproved devices in the core zone draw fines of CNY 1,000 to 30,000, and harmful interference fines of up to CNY 200,000; flight paths were moved away from the dish.

Visiting scientists may not take electronics past the second gate while the telescope is observing, and they do their computer work in a shielded control room. There is no mobile signal at the checkpoint. Rooms on site cost CNY 200 to 450 a day.