Brazilian Decimetric Array Project: Completion and Results of Phase I

H.S. Sawant$^1$, J.R. Cecatto$^1$, F.C.R. Fernandes$^1$, BDA Team$^2$

$^1$National Institute for Space Research - INPE, San Jose dos Campos, SP, Brazil
$^2$Participants from:

Department of Computer Sciences, Univ. of Puc Minas DC/PUCMinas, Pocos de Caldas, Brazil
Center of Radio Astronomy and Astrophysics, CRAAM/INPE, Univ. Mackenzie, Sao Paulo, Brazil
Department of Engineering and Computer Sciences DC/UFSCar, Sao Carlos, Brazil
Indian Institute of Astrophysics IIA, Bangalore, India
National Center of Radio Astronomy NCRA/GMRT/TIFR, Pune, India
New Jersey Institute of Technology, New Jersey, U.S.A.
University of California at Berkeley, Berkeley, U.S.A.

A team of Brazilian scientists and engineers, with a collaboration of national and international institutions, is coordinating efforts on development of the Brazilian Decimetric Array (BDA) Project, the unique decimeter interferometer in Latin America. The BDA employs modern radio interferometry techniques and it will produce images of radio sources with high spatial and time resolution and high dynamic range, including solar radio images of lower corona where energy release to solar flare takes place, also with application to space weather forecasting. The Phase I of the development of the BDA was scientifically and technically completed in 2005. In Phase I, a five-element interferometer was completed developed at INPE using a 4-meter diameter alt-azimuth mounted mesh type parabolic antenna, having almost complete tracking capability. The array are installed at Cachoeira Paulista, Brazil (Longitude: -45$^\circ$ 20$^\prime$ W and Latitude: -22$^\circ$ 41$^\prime$ S), with maximum base lines up to 216 meter in the E-W direction, and having spatial resolution $<$ 3 minutes of arc at 1.4 GHz. This array operates in the frequency range of (1.2 - 1.7) GHz. Solar and non-solar observations are carried out for 120 days in 2005. Solar flares have been observed at 1.4 GHz. Results are being investigated. One dimensional maps of the solar brightness temperature associated with solar soft X-ray observed by GOES and their time variation were also obtained. The sixth antenna is being presently added which will improve the imaging quality of the observations. We have initiated the development of the Phase II of the BDA, where more 22 antennas will be added to the existing array. We intend to finish the development of this phase by March, 2009. Here, we present the status of the BDA project and details of the instrumentation developed for Phase I. Results of solar observations carried out using the PBDA, in the frequency of 1.6 GHz, and image capability of the instrument for solar and space weather investigations will be presented. The improvement of u-v plan coverage with declinations and, details of sensitivity as a function of integration of time for six-element array will be also presented and discussed.