ILWS - International Living With Star The Brazilian Decimetric Array (BDA) Contribution to Space Weather Investigations H.S. Sawant, J.R. Cecatto, F.C.R. Fernandes, R.R. Rosa, J.E.R. Costa and BDA team members

ILWS - International Living With Star Valley in Chachoeira Paulista selecting “T”array site, Prof. G. Swarup, Director GMRT – India Dr. H.S. Sawant - INPE and Dr. Hari Om Vats – PRL - India discussing with civil engineer on 13 th September 1997.

ILWS - International Living With Star PARTICIPATING INSTITUTIONS Institutes: National Institute for Space Research – INPE: Astrophysics Division (DAS) Laboratory of Applied Computation (LAC) Aeroespace Electronic Division (DEA) Laboratory of Integration and Tests (LIT) Federal University of São Carlos (UFSCar) Catholic University of Minas Gerais (PUC-MG) Center of Radio Astronomy – Mackenzie (CRAAM) – INPE Tata Institute of Fundamental Research (TIFR) – GMRT – NCRA - India Indian Institute of Astrophysics (IIA) – Bangalore, India University of California - Berkeley (UCB), Dept. of Radioastrophysics, USA New Jersey Institute of Technology (NJIT), USA Industries/Companies: Centro de Pesquisa Renato Archer - CENPRA - - Campinas Intelligent Motion Technology, IMT- LTd. – Pune India Neuron Ltd. - São José dos Capos - Brazil UC GRAÇA – São José dos Campos - Brazil. F4R FIBRA PARA RADIO – Campinas Two micro-companies Eletronics / Electrical

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SOLAR PHYSICS GROUP Hanumant Shankar Sawant José Roberto Cecatto Francisco C. R. Fernandes Reinaldo Roberto Rosa Joaquim E. R. Costa

ILWS - International Living With Star Number of antennas26 Number of baselines325 Configuration“T” shape Frequency bands1.2 – 1.7, 2.8 and 5.6 GHz Temporal resolution~100 ms Antenna diameter (alt-az mount) 4 m Angular resolution ~2,8’, ~1,4’ e ~0,8’ Maximum baseline252 m Minimum baseline9 m Field of view 40’  40’ of arc Sensitivity 5.6 GHz with  t = 1 s) ~285 Jy/beam (Sun) and ~1,8 Jy/beam (others) Tracking Coverage340 0 in azimuth and in elevation Pointing accuracy< 3 arcmin CHARACTERISTICS OF BDA PHASE II

ILWS - International Living With Star Methods: The development of BDA phase II involves the participation of several local companies and national and international institutes.

ILWS - International Living With Star DISTRIBUTION OF RADIOHELIOGRAPHS IN THE WORLD.

ILWS - International Living With Star BDA PROTOTYPE OF 5 ELEMENTS AT INPE-SJC. CAMPUS

ILWS - International Living With Star BDA 5 ELEMENTS SHIFTED TO FINAL SITE OF BDA AT CACHOEIRA PAULISTA

ILWS - International Living With Star 252 m 2268 m 252 m 1170 m E 9m 162m N W S 18m36m 18m 36m 252 m 18m BDA CONFIGURATION PHASE II AND PHASE III

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ANGULAR RESOLUTION OF THE EXISTING SOLAR RADIO-HELIOGRAPHS

ILWS - International Living With Star SOLAR IMAGE CAPABILITY Nobeyama 17 GHzBDA “Dirty” ImageBDA “Clean” Image

ILWS - International Living With Star SCIENTIFIC GOALS  BDA will produce high spatial and time resolution images of radio sources with high dynamic range.  BDA will provide solar radio images in the lower corona where flare energy release takes place; flare and CME analysis will lead to a better understanding of the fundamental problems in solar physics; spectral tomography technique being developed for application to space weather forecasting.  BDA will be very useful for galactic and extra-galactic investigations of the southern sky not accessible to VLA.

ILWS - International Living With Star Normally, in observations of optical coronagraphs the solar disk is occulted and hence only CMEs propagating perpendicular to the line of sight are observed. However, in radio observations, there is no occultation of solar disk and hence CMEs on the disk can also be observed by radio heliographs such as BDA. It is the Earth-directed CMEs that are most important for space weather. Such CMEs can be detected in their initial stages before they appear in the coronagraphic field of view and hence help identify the solar sources of Earth-directed CMEs. CMEs drive shocks, accelerate particles, and produce geomagnetic storms.

ILWS - International Living With Star The observability of CME substructures in microwaves can be assessed using the simple formula for free ‐ free optical depth (Gopalswamy, 1999): tff = α ∫n 2 f − 2T −3/2 dl, where α ~ 0.2 for T > 10 4 and ~ 0.08 for T < 10 4, n = electron density, f = observing frequency and T = electron temperature. ∫n 2 dl is the emission measure of the structure we are interested in, dl being the elemental length along the line of sight BDA will image the CME Core

ILWS - International Living With Star CORONAL HOLES Coronal holes are important large-scale structures on the Sun, which produce high-speed solar wind streams (HSS). BDA can readily observe the coronal holes at all frequencies as depressions. When HSS collide with the neighboring slow solar wind, they produce large-scale magnetized plasma structures known as the corotating interaction regions (CIRs). CIRs are responsible for a different type of geomagnetic storms that are known for producing MeV electrons in Earth’s magnetosphere. These electrons can be hazardous to satellites in the magnetosphere, and hence important for space weather prediction. Observing coronal holes in the equatorial region of the Sun is thus very important. In addition, coronal holes will appear as depressions at all the BDA frequencies, so the structure of coronal holes can also be studied.

ILWS - International Living With Star Advanced Data Analysis for BDA : Spectral Analysis for Time Series Gradient Spectral Analysis and Singularity Spectra for nonlinear physical processes characterization: particle acceleration and magnetic reconnections Lab for Computing and Applied Mathematics (LAC-INPE) (R.R.Rosa) Image Wavelet Analysis for characterization of transverse oscillation propagating slow waves and standing longitudinal waves by using coronal period mapping, pixelising wavelet filtering (PWF) and spatial decomposition by using2D Fourier transform along coronal loops (Institute for Solar-Terrestrial Physics, Irkutsk (R.A. Sych).

ILWS - International Living With Star Conclusion Radio telescopes like the BDA can readily observe the inner parts of CMEs (the prominence core and cavity) when they start on the Sun, thus providing advanced warning of impending adverse space weather at least one day ahead of time. Similarly, the BDA will be able to observe the presence of coronal holes on the disk and forecast high speed streams. Observation of BSS will compliment these investigations. Measurements of the velocity of the type II shock will permit to predict the interaction of the shock with magnetosphere in advance by coupe of hours to a day. From spectral investigations long duration busts with high flux also will predict the launch of CME. Observed flux of 2.8 GHz by using Messoraty et al’s model also can predict launch of CME in advance by couple of hours FILAMENT DEPR. ERU. PRO. PATCH ENHA. HV – SW CIR – MeV MEGN.

ILWS - International Living With Star Acknowledgements