The Frequency Agile Solar Radiotelescope (FASR) Dale E. Gary New Jersey Institute of Technology

The Frequency Agile Solar Radiotelescope (FASR)

Dale E. Gary

New Jersey Institute of Technology

IAU Meeting 2006 Aug 21 NJIT Center for Solar Terrestrial Research 2 / 22


FASR Instrument (Antennas)

Three arrays, 4.2 km baselinesThree arrays, 4.2 km baselines

Array Designation

Number of Antennas

Frequency Range

Antenna Size

FASR-A High Frequency Array

~1002-20 GHz

2-30 (goal)2 m

FASR-BLow Frequency Array

~60 0.2-3 GHz 6 m

FASR-CLog-Periodic Dipole Array

~4050-300 MHz

20-300 (goal)Log-

dipole



FASR Instrument (Receivers)

Broadband RF transmission, Digital FX CorrelatorBroadband RF transmission, Digital FX Correlator

Quantity Spec

Frequency Resolution0.01% (internal)

1-3% (output)

Time Resolution100 ms (FASR-B/C)

1 s (FASR-A)

Polarization Stokes IV (QU)

Instantaneous Bandwidth ~1 GHz


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

Full capability to address a broad range of solar Full capability to address a broad range of solar science:science:

1.1. Nature and evolution of coronal magnetic fieldsNature and evolution of coronal magnetic fields

2.2. Physics of flaresPhysics of flares

3.3. Drivers of space weatherDrivers of space weather

4.4. Physics of the quiet solar atmospherePhysics of the quiet solar atmosphere

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

Full capability to address a broad range of solar Full capability to address a broad range of solar science:science:

1.1. Nature and evolution of coronal magnetic fieldsNature and evolution of coronal magnetic fields

2.2. Physics of flaresPhysics of flares

3.3. Drivers of space weatherDrivers of space weather

4.4. Physics of the quiet solar atmospherePhysics of the quiet solar atmosphere


Objectives to Measurements

Key Science Objectives

Science GoalsMeasurement

GoalsObservables

Emission Mechanism

Measurement Requirements1

D Tb (K) (s)

Objective 1: The nature and evolution of coronal magnetic Fields

A: Coronal Magneto-graphy of active regions

Strong magneticfields (>150 G)

a: Active region

multi- Tb maps Gyroresonance 1-18 1% 3000 1000 1800

B: Coronal Magneto-graphy of the quietSun

LOS magnetic Fields

b: Full-Sun

multi- Tb maps Free-free 1-20 1% 1000 300 1800

C: Magnetic connectivity of the corona to the heliosphere

Coronal field and topology

1a, 1b See above - - - - -

c: Active region multi- poln Maps

Mode-coupling depolarization surface

1-20 1% 1000 1000 1800

d: dm- and m- type III bursts

Plasma 0.03-3 1% 1000 105 0.01


Magnetic Field Spectral DiagnosticsMagnetic Field Spectral Diagnostics

• Model spectra along 2 Model spectra along 2 lines of sight: lines of sight: aa) negative polarity ) negative polarity sunspot, sunspot, bb) positive ) positive polarity sunspot.polarity sunspot.

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

Model from Mok et al., 2004;

Simulation from Gary et al. 2004


2D Magnetogram2D Magnetogram• BB map deduced map deduced

from 1—24 GHz from 1—24 GHz spectra (spectra (bb) match ) match the model (the model (aa) very ) very well, everywhere well, everywhere in the region. (in the region. (cc) ) is a comparison is a comparison along a line along a line through the center through the center of the region.of the region.

• The fit only works The fit only works down to 119 G down to 119 G (corresponding to (corresponding to ff = 3 = 3 ffBB = 1 GHz) = 1 GHz)

from Gary et al. 2004





GoalsObservables

Emission Mechanism


D Tb (K) (s)




a: Active region



LOS magnetic Fields

b: Full-Sun




1a, 1b See above - - - - -



1-20 1% 1000 1000 1800


Plasma 0.03-3 1% 1000 105 0.01


Bl from Free-Free Emission• With sufficient With sufficient

polarization polarization sensitivity, sensitivity, BBll

can be deduced can be deduced everywhere everywhere down to ~ 20 G down to ~ 20 G using:using:

where where nn is the is the spectral indexspectral index

from Gelfreikh, 2004—Ch. 6from Gary & Hurford, 2004—Chapter 4





GoalsObservables

Emission Mechanism


D Tb (K) (s)




a: Active region



LOS magnetic Fields

b: Full-Sun




1a, 1b See above - - - - -



1-20 1% 1000 1000 1800


Plasma 0.03-3 1% 1000 105 0.01


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.

from Ryabov, 2004—Chapter 7


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)


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


FST System• HardwareHardware

1-9 GHz RF 500 MHz instantaneous BW Record full-res time-domain

signal, off-line processing

• Block DiagramBlock Diagram

ImageRejection

D-C Modules &Variable LO

Chassis

AcqirisDigitizer

Control/RecordingComputer

CAN Bus D-C Mod Ctrl

FrontEnd Box

BlockDown-converter

Chassis

FrontEnd Box

FrontEnd Box

OVSAAnt 5RF

OVSAAnt 6RF

OVSAAnt 7RF

FO Rcvr &AmplifierChassis

Parallel Port LO Ctrl

DIO Switch Ctrl

Fiber

Dig

itize

r C

trl


Results (RFI)

• 10000-pt spectra (10000-pt spectra (dd = = 50 kHz), 10 50 kHz), 10 s time s time resolution sample of resolution sample of local interference local interference signalsignal

• Goal is to identify and Goal is to identify and excise interference in excise interference in real timereal time

• Hiro Kawakubo and Hiro Kawakubo and Chris Ruf (U Mich) are Chris Ruf (U Mich) are studying use of studying use of kurtosis statistickurtosis statistic Time

Frequency


Results (Satellites)• First Fringes (GPS satellite, L1 First Fringes (GPS satellite, L1

signal, 1575.42 MHz)signal, 1575.42 MHz)


Results (Satellites)• Geostationary Satellite Geostationary Satellite

Galaxy 10RGalaxy 10R• Can phase information Can phase information

be used for calibration?be used for calibration?• Overlapping channels Overlapping channels

are linearly (H and V) are linearly (H and V) polarized, which offers polarized, which offers possibility of linear possibility of linear polarization calibrationpolarization calibration


20 s of FST Amplitude Data20 s of FST Amplitude Data

B5.1 Flare (2006 Apr 05)

Results (Solar)


FST Amplitude & Corrected Phase

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

polarization to another

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

polarization to another


Status and ConclusionStatus and Conclusion• FASR is being designed to address an FASR is being designed to address an

extremely rich range of solar science, utilizing extremely rich range of solar science, utilizing state-of-the-art technology. state-of-the-art technology.

• Some aspects of the instrument are currently Some aspects of the instrument are currently being prototyped.being prototyped.

• Most recent proposal received highest Most recent proposal received highest recommendation, but funding has been recommendation, but funding has been reduced and delayed by funding agency.reduced and delayed by funding agency.

• Next step is to construct a 10-element Next step is to construct a 10-element prototype array, to be ready by 2010. Proposal prototype array, to be ready by 2010. Proposal to be submitted as soon as possible.to be submitted as soon as possible.

• FASR is being designed to address an FASR is being designed to address an extremely rich range of solar science, utilizing extremely rich range of solar science, utilizing state-of-the-art technology. state-of-the-art technology.

• Some aspects of the instrument are currently Some aspects of the instrument are currently being prototyped.being prototyped.

• Most recent proposal received highest Most recent proposal received highest recommendation, but funding has been recommendation, but funding has been reduced and delayed by funding agency.reduced and delayed by funding agency.

• Next step is to construct a 10-element Next step is to construct a 10-element prototype array, to be ready by 2010. Proposal prototype array, to be ready by 2010. Proposal to be submitted as soon as possible.to be submitted as soon as possible.



FASR EndorsementsFASR Endorsements2001 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)

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)


FASR Signal Path

Correlator and DSP

12-bitDigitizer

Analog fiber-optic cable

On-lineCalibration

Data Storage

LAN

Internet

Burstmonitor(s)

RFImonitor(s)

RF Converter Room IF Processor Room

Control Room

RF-IFconverter

Bac

k-en

d

LOdistribution

Polyphase Filter Bank

1-bit Sampler

Front-end

Element

Com

puti

ng

Sys

tem

From other

antennas


FASR Science Community Input

• International Science Workshop, 2002 May, International Science Workshop, 2002 May, Green Bank, WVGreen Bank, WV

• Special session, 2002 Special session, 2002 American Astronomical American Astronomical SocietySociety meeting meeting

• Kluwer ASSL* Book: Kluwer ASSL* Book: Solar & Space-Weather Solar & Space-Weather Radiophysics Radiophysics (17 chapters on all aspects of (17 chapters on all aspects of radiophysics of the Sun and inner heliosphere, radiophysics of the Sun and inner heliosphere, will appear by end of summer)will appear by end of summer)

*Astrophysics & Space Science Library*Astrophysics & Space Science Library


Coronal MagnetogramsCoronal Magnetograms Accurate Accurate

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

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

from Gary et al. 2004

Documents

The Frequency Agile Solar Radiotelescope (FASR) Dale E. Gary New Jersey Institute of Technology