A Wide Field 90 cm VLA Image of the Galactic Center Region

T. N. LaRosa, Namir E. Kassim, T. Joseph W. Lazio, & S. D. Hyman

Paper: Astronomical Journal, 2000 January

Weblink: http://rsd-www.nrl.navy.mil/7213/lazio/GCatlas/


Abstract:

We present a wide-field, high dynamic range, high resolution long wavelength ( lambda = 90 cm) VLA image of the Galactic center region. The image is centered on Sgr A, covers an area of 4^o * 5^o with an angular resolution of 43'' and has a rms sensitivity of ~ 5 \mjybm. The image was constructed from archival VLA data of Pedlar et al. (1989) and Anantharamaiah et al. (1991) using new 3-D image restoration techniques. These 3-D 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 20/90 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 that 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.


Preprints available from the authors at lazio@sne.nrl.navy.mil , or the raw TeX (no figures) if you click here.

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