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The Frequency Agile Solar Radiotelescope (FASR). Dale E. Gary New Jersey Institute of Technology. FASR Instrument (Antennas). Three arrays, 4.2 km baselines. FASR Instrument (Receivers). Broadband RF transmission, Digital FX Correlator. FASR Science Goals.

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the frequency agile solar radiotelescope fasr

The Frequency Agile Solar Radiotelescope (FASR)

Dale E. Gary

New Jersey Institute of Technology

fasr instrument antennas
FASR Instrument (Antennas)

Three arrays, 4.2 km baselines

NJIT Center for Solar Terrestrial Research

fasr instrument receivers
FASR Instrument (Receivers)

Broadband RF transmission, Digital FX Correlator

NJIT Center for Solar Terrestrial Research

fasr science goals
FASR Science Goals

Designed to be the world’s premier solar radio facility for at least two decades after completion.

Full capability to address a broad range of solar science:

  • Nature and evolution of coronal magnetic fields
  • Physics of flares
  • Drivers of space weather
  • Physics of the quiet solar atmosphere

NJIT Center for Solar Terrestrial Research

objectives to measurements
Objectives to Measurements

NJIT Center for Solar Terrestrial Research

magnetic field spectral diagnostics
Model spectra along 2 lines of sight: a) negative polarity sunspot, b) positive polarity sunspot.

The coronal temperature and the magnetic field strength can be read directly from the spectra.

Magnetic Field Spectral Diagnostics

Model from Mok et al., 2004;

Simulation from Gary et al. 2004

NJIT Center for Solar Terrestrial Research

2d magnetogram
2D Magnetogram
  • B map deduced from 1—24 GHz spectra (b) match the model (a) very well, everywhere in the region. (c) is a comparison along a line through the center of the region.
  • The fit only works down to 119 G (corresponding to f = 3 fB = 1 GHz)

from Gary et al. 2004

NJIT Center for Solar Terrestrial Research

objectives to measurements1
Objectives to Measurements

NJIT Center for Solar Terrestrial Research

b l from free free emission
With sufficient polarization sensitivity, Bl can be deduced everywhere down to ~ 20 G using:

where n is the spectral index

Bl from Free-Free Emission

from Gelfreikh, 2004—Ch. 6

from Gary & Hurford, 2004—Chapter 4

NJIT Center for Solar Terrestrial Research

objectives to measurements2
Objectives to Measurements

NJIT Center for Solar Terrestrial Research

magnetic topology from qt layer
Upper panels show radio “depolarization line” (DL) at a single frequency due to mode-conversion at a quasi-transverse (QT) layer, vs. photospheric neutral line (NL).

Using FASR’s many frequencies, a QT surface can be mapped in projection. The surface changes greatly with viewing angle.

Magnetic Topology from QT Layer

from Ryabov, 2004—Chapter 7

NJIT Center for Solar Terrestrial Research

prototyping efforts
Prototyping Efforts
  • Green Bank Solar Radio Burst Spectrometer (feed development)
  • FASR Subsystem Testbed--FST (design platform, RFI mitigation, solar observations)
  • French Activities (RFI mitigation, FPGA technology)

NJIT Center for Solar Terrestrial Research

green bank solar radio burst spectrometer
Green Bank Solar Radio Burst Spectrometer

Feed Development

  • 20-70 MHz system using “fat dipole”
  • 50-250 MHz feed on 45-foot telescope
  • 200-1070 MHz on 45-foot telescope

http://www.astro.umd.edu/~white/gb/

NJIT Center for Solar Terrestrial Research

fst system
FST System
  • Hardware
    • 1-9 GHz RF
    • 500 MHz instantaneous BW
    • Record full-res time-domain signal, off-line processing
  • Block Diagram

NJIT Center for Solar Terrestrial Research

results rfi
Results (RFI)
  • 10000-pt spectra (dn = 50 kHz), 10 ms time resolution sample of local interference signal
  • Goal is to identify and excise interference in real time
  • Hiro Kawakubo and Chris Ruf (U Mich) are studying use of kurtosis statistic

Frequency

Time

NJIT Center for Solar Terrestrial Research

results satellites
Results (Satellites)
  • First Fringes (GPS satellite, L1 signal, 1575.42 MHz)

NJIT Center for Solar Terrestrial Research

results satellites1
Results (Satellites)
  • Geostationary Satellite Galaxy 10R
  • Can phase information be used for calibration?
  • Overlapping channels are linearly (H and V) polarized, which offers possibility of linear polarization calibration

NJIT Center for Solar Terrestrial Research

slide20

Results (Solar)

B5.1 Flare (2006 Apr 05)

20 s of FST Amplitude Data

NJIT Center for Solar Terrestrial Research

slide21

FST Amplitude & Corrected Phase

Burst locations essentially identical from burst to burst, and from one polarization to another

NJIT Center for Solar Terrestrial Research

status and conclusion
Status and Conclusion
  • FASR is being designed to address an extremely rich range of solar science, utilizing state-of-the-art technology.
  • Some aspects of the instrument are currently being prototyped.
  • Most recent proposal received highest recommendation, but funding has been reduced and delayed by funding agency.
  • Next step is to construct a 10-element prototype array, to be ready by 2010. Proposal to be submitted as soon as possible.

NJIT Center for Solar Terrestrial Research

slide24

FASR Endorsements

  • 2001 Astronomy & Astrophysics Survey Committee
  • Ranked as one of 17 priority projects for this decade
  • one of 3 solar projects, with ATST and SDO
  • 2003 Solar and Space Physics Survey Committee
  • Ranked as top priority in small (<$150 M) projects
  • 2002-2004: Design Study (NSF/ATI)
  • 3 workshops for community input
  • Science consensus, hardware and software design options, and development of management plan.
  • 2004-2006: FASR Long-Lead Prototyping Proposal (NSF/ATI)

NJIT Center for Solar Terrestrial Research

fasr signal path
FASR Signal Path

Element

RF Converter Room

IF Processor Room

LO

distribution

Front-end

Analog fiber-

optic cable

Polyphase Filter Bank

RF-IF

converter

12-bit

Digitizer

1-bit Sampler

Correlator and DSP

Back-end

From other antennas

LAN

Internet

Data

Storage

On-line

Calibration

Control Room

Burst

monitor(s)

RFI

monitor(s)

Computing System

NJIT Center for Solar Terrestrial Research

fasr science community input
FASR Science Community Input
  • International Science Workshop, 2002 May, Green Bank, WV
  • Special session, 2002 American Astronomical Society meeting
  • Kluwer ASSL* Book: Solar & Space-Weather Radiophysics (17 chapters on all aspects of radiophysics of the Sun and inner heliosphere, will appear by end of summer)

*Astrophysics & Space Science Library

NJIT Center for Solar Terrestrial Research

coronal magnetograms
Accurate simulation of FASR coronal magnetograms of potential and non-potential active region, and difference compared with current-density map from the model.Coronal Magnetograms

from Gary et al. 2004

NJIT Center for Solar Terrestrial Research