A Wide-Field 90 Centimeter VLA Image of the Galactic Center Region
KENNESAW STATE UNIV GEORGIA DEPARTMENT OF BIOLOGICAL AND PHYSICAL SCIENCES
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We present a wide-field, high dynamic range, high-resolution, long-wavelength lambda 90 cm Very Large Array VLA image of the Galactic center region. The image is centered on Sgr A, covers an area of 4 deg. x 5 deg. with an angular resolution of 43, and has a rms sensitivity of approx. 5 mJy beamexpo. -1. The image was constructed from archival 1989 and 1991 VLA data of Pedlar et al. and Anantharamaiah et al. using new three-dimensional image restoration techniques. These three-dimensional imaging techniques resolve the problem of non-coplanar baselines encountered at long wavelengths and yield distortion-free imaging of far-field sources with improved sensitivity. At lambda 90 cm the VLA is sensitive to both thermal and nonthermal emission and the resulting image gives an unprecedented contextual perspective of the large-scale radio structure in this unique and complicated region. We have catalogued over a hundred sources from this image and present for each source its 90 cm flux density, position, and size. For many of the small-diameter sources, we also derive the 2090 cm spectral index. The spectral index as a function of length along several of the isolated nonthermal filaments has been estimated and found to be constant. We have found six new small-diameter sources, as well as several extended regions of emission, which are clearly distinct sources that have not been previously identified at higher frequencies. These data are presented as a first epoch of VLA observations that can be used to search for source variability in conjunction with a second epoch of observations that were recently initiated.