Solar radio observations in BelgiumC. Marqué, F. Clette, J.-L. Dufond,A. Ergen, J. Magdalenic, B. DabrowskiRoyal Observatory of Belgium2nd LOFAR Solar KSP Workshop, Postdam June 24-25, 2009

Outlines

Historical overview Presentation of the solar radio projects The CALLISTO spectrograph Synergies between LOFAR & solar physics @

ROB Scientific activities Conclusion

Historical overview

•1956: Routine radio flux observations at 169 & 610 MHz.•1958-1972: Construction of the 408 MHz radioheliograph (48-antenna interferometer): operated only in slow-drift mode.•Lack of manpower and excessive maintenance workload: decommissioning of the interferometer (Sept. 2002) and of the 610 MHz radiometer (Aug. 2004)

•Location: Humain (Marche-en-Famenne), 100km SE of Brussels•Operated by ROB since 1954

The Humain station

A new development context: the STCE

STCE: Solar-Terrestrial Center of Excellence Cross-disciplinary multi-institute structure dedicated to Sun-Earth

relation studies Belgian government commitment to support and bring together

Belgian experts in solar physics, geomagnetism and aeronomy. Teams from 3 federal institutes: ROB, BISA (space areonomy), RMI

(meteorology) More information at http://www.stce.be

Solar activity monitoring from ground-based instruments (optical, radio) is one of the ROB WPs

The Humain redeployment plan Primary goals: monitoring of solar activity and research:

solar flares, CMEs & irradiance. Refurbishment of available hardware (now in progress):

Selection of a couple of antenna, new control system New receivers

2 specific kinds of instruments: Radiometers at selected dm and cm wavelengths (0.5-10

GHz) for irradiance studies and flare physics; primary freq. 2.8 GHz (F10.7 cm). (DRAO, Pentincton)

Spectrometers in the m/dm range (CALLISTO) and later in the cm domain for flare/CME related physics.

Direct connection with the SIDC Regional Warning Center for Europe (ROB, Brussels)

What is CALLISTO?

It’s a network of instruments located around the world for an extended solar monitoring and for RFI mitigation

CALLISTO: http://helene.ethz.ch/instrument/callisto/callisto_nf.htmlCALLISTO solar data: http://pandora.ethz.ch:8080/frontend/

CALLISTO is a low-cost, sweep frequency radio receiver primarily designed for solar observations (sporadic solar outbursts), built and designed by C. Monstein from the ETHZ institute

CALLISTO

•Made from consumer electronics hardware (Philips TV tuner)•PC-controlled hardware with RS232 connection•Software for automatic observations (frequency program, schedule…)•Fine frequency overview mode (whole frequency range scanned at 62.5 kHz), takes about a min.

Parameter SpecificationFrequency range

45-870 MHz

Frequency resolution

62.5 kHz

Bandwidth 300 kHz (-3dB)

Dynamic range ~50 dBSensitivity 25±1 mV/dBNoise figure <10dBSampling rate 800-1000

samp/sWeight 800gDimensions 11x8x20.5

cmHardware cost < 200$

CALLISTO in Humain

Log-periodic antenna, with Sun tracking capabilities

Observing since May 2008 45-400 MHz (test phase) Spectrum monitoring 2nd Callisto to be installed

for high freq. monitoring Near real time:

http://sidc.be/humain

Belgian RFI situationSpectral overview, pointing at the Sun, (Ref: 50 Ohm)

Short terms development in spectrography

Extension of the available spectrum between 20 MHz and 3 GHz for solar observation

RFI mitigitation (local source) Data processing effort for automatic burst

recognition (space weather forecasts @ ROB), cataloging

Development of an home-made spectrograph

Belgian solar community & LOFAR

Triggering of “burst mode” for LOFAR could be made on spectrograph observations such as CALLISTO (local receiver or rely on available network)

An automatic burst detection could feed the solar observation mode

PROBA2 (SWAP & LYRA): EUV imager and radiometer. Launch November 2nd 2009

STCE science could benefit (meteor…)

Science activities: radio team

Small group: 4 scientists (2 full time), 2 technical staff ( +2 to be recruted)

Hardware development (spectro and radiometers): just started

A primary science target: flare and CMEs Density modeling: necessary for data analysis in

EUV, radio Two efforts: one with J. Magdalenic (fully radio) One with B. Dabrowski: EUV forward modeling

Science activities: flares, CMEs and shocks

Projects related to physics of flares and CMEs with Jasmina Magdalenic - Zhukov:

Global waves and shocks: study of coronal parameters (density, temperature, Alfvén velocity distribution)

Belgian roposal for the propagation of shock waves from the corona to the Earth

Both rely on a joint study of spectrographic and imaging radio data (Nançay Radioheliograph, LOFAR)

Position of the NRH radio source → converted to radial heights

→ frequency (radial heights)

The evolution of the dominant NRH source is compared with the type II features in dynamic spectrum.

14:2214:21 14:23 14:24 14:25 14:26 14:27 UT

150

200

300

500

700

1000

f (M

Hz)

151MHz164MHz

237MHz

411MHz432MHz

327MHz

Fundamentalband

Harmonicband

411 MHz, 14:22:34 UT

Estimation of the

coronal electron density

observations show coronal electron density between 5x Saito (Saito et al., 1970) what is close to 2x Newkirk (Newkirk et al., 1966), and 2x Saito. steep decrease of coronal density → consequence of possible projection effects?

40

80

120

160

200

240

280

1 1.1 1.2 1.3 1.4 1.5 1.6H (Ro)

f (M

Hz)

LFB

164 MHz

151MHz

3.5xSaito

2xSaito

2xNewkirk

5xSaito

• f ~ 216 MHz, 5x Saito → density ~ 5 · 108 cm-3

• f ~ 76 MHz, 2x Saito → density ~ 6 · 107

cm-3

f n 9 e1/2~

H (R )O

5x Saito

2x Saito

n(c

m-3

)

Conclusion

Revival of solar radioastronomy in Belgium (still modest)

Solar spectrography and irradiance Numerous links with imaging instruments like

Nançay and LOFAR: for solar activity monitoring and “pure” science purpose