A Wide-Field 90 Centimeter VLA Image of the Galactic Center Region

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Abstract
We present a wide-—eld, high dynamic range, high-resolution, long-wavelength (j \ 90 cm) VLA image of the Galactic center region. The image is centered on Sgr A, covers an area of 4¡ ) 5¡ with an angular resolution of 43A, and has a rms sensitivity of B5 mJy beam~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-—eld sources with improved sensitivity. At j \ 90 cm the VLA is sensitive to both thermal and non- thermal 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 —ux density, position, and size. For many of the small- diameter sources, we also derive the 20/90 cm spectral index. The spectral index as a function of length along several of the isolated nonthermal —laments 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 identi—ed at higher frequencies. These data are presented as a —rst epoch of VLA observations that can be used to search for source variability in con- junction with a second epoch of observations that were recently initiated.

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