Summary of the Frequency-Agile Solar Radiotelescope (FASR) Project

Science Goals

The Frequency-Agile Solar Radiotelescope is a multifrequency (0.03 - 30 GHz) imaging array composed of many (~100) antennas. It is designed specifically for observing the Sun. It will produce high quality images with high spatial resolution (1" at 20 GHz), high spectral resolution (Dn/n ~ 0.1 - 1%) and high time resolution (< 0.1 s).

Based on extensive discussions among members of the scientific community, several areas have been identified in which FASR is expected to make significant new contributions:

  • Nature and evolution of coronal magnetic fields
  • Physics of solar flares
  • Drivers of Space Weather
  • The quiet Sun

In addition, the observational capabilities of FASR, which represent a quantum leap beyond current radio instrumentation, gives the instrument tremendous potential for new discoveries beyond any that we can now anticipate.


Unique Science to be Addressed

The spatially resolved microwave, decimetric, and meterwave spectrum allows FASR to bring to bear powerful, spectrally-based, radio diagnostics. The radio spectrum contains unique information about the solar atmosphere and the acceleration of energetic particles that cannot be studied in any other way. The unique science to be addressed includes:

  • measurement of coronal magnetic fields (coronal magnetography), using a variety of techniques applicable to active regions, flaring loops, CMEs, and the quiet Sun
  • location and properties of the site of energy release
  • electron acceleration and transport, and the thermal response
  • the detection and characterization of coronal mass ejections on the disk
  • the detection and characterization of waves, shocks, and origins of solar energetic particles
  • coronal heating, and structure and dynamics of the chromosphere

FASR science is presented in more detail in the overview document and in a Kluwer Astrophysics and Space Science Library volume listed in the links at right.


For More Information

Full Report
Kluwer ASSL vol. 303, Solar and Space Weather Radiophysics

Current Status

FASR was one of 17 projects recommended for this decade by the Astonomy and Astrophysics Survey Committee, and received the number 1 priority rating of the Solar and Space Physics Survey Committee in the "small projects" category. FASR is currently in a Phase A design study, and has received small amounts of funding for targeted prototyping activities. The FASR team is preparing a short-duration Phase B proposal for design and development, to be submitted for FY 2005 funding. The final construction proposal will be submitted in FY 2006, with expected completion of the project by 2010.


FASR Timeline
Phase A Study
Phase B Study
First Science

Design Summary

The array will consist of three separate antenna systems in order to cover the entire 3 decades of frequency from 30 MHz to 30 GHz. The two highest bands will utilize 6 m and 2 m antennas, respectively. The low band will utilize fixed log-periodic or active dipoles, or Vivaldi -type feeds. The FASR specifications are shown in the table below.

FASR Specifications

Angular resolution

20/nGHz arcsec

Frequency range

30 MHz 30 GHz

Number channel pairs


Total instantaneous BW

2 GHz

Frequency resolution

0.3-3 GHz: 0.1%
<0.3, >3 GHz: 1%

Time resolution

0.3-3 GHz: 10 ms
<0.3, >3 GHz: 100 ms




Number antennas

3-30 GHz: 100
0.3-3 GHz: 80
<0.3 GHz: 60

Size antennas

3-30 GHz: 2 m
0.3-3 GHz: 6 m
<0.3 GHz: LPDA

Maximum antenna spacing

6 km


Absolute positions

1 arcsec

Absolute flux calibration


DTb (snapshot) 1000 K

Last Updated: 17 Jun 2004  by Dale E. Gary