Solar radio observations in Belgium C. Marqué, F. Clette, J.-L. Dufond, A. Ergen, J. Magdalenic, B. Dabrowski Royal Observatory of Belgium 2 nd 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 ROB  Scientific activities  Conclusion

Historical overview 1956 : Routine radio flux observations at 169 & 610 MHz : 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 ) and of the 610 MHz radiometer ( Aug ) 1956 : Routine radio flux observations at 169 & 610 MHz : 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 ) and of the 610 MHz radiometer ( Aug ) Location: Humain (Marche-en- Famenne), 100km SE of Brussels Operated by ROB since 1954 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 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 ( 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: CALLISTO solar data: 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. ParameterSpecification Frequency range MHz Frequency resolution 62.5 kHz Bandwidth300 kHz (-3dB) Dynamic range~50 dB Sensitivity25±1 mV/dB Noise figure<10dB Sampling rate samp/s Weight800g Dimensions11x8x20.5 cm Hardware cost< 200$

CALLISTO in Humain  Log-periodic antenna, with Sun tracking capabilities  Observing since May 2008  MHz (test phase)  Spectrum monitoring  2 nd Callisto to be installed for high freq. monitoring  Near real time:

Belgian RFI situation Spectral 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 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 2 nd 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. Fundamental band Harmonic band 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? f ~ 216 MHz, 5x Saito → density ~ 5 · 10 8 cm -3 f ~ 76 MHz, 2x Saito → density ~ 6 · 10 7 cm -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