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 LaRosa.90cm.tex Astronomical Journal, 2000 January
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%\lefthead{LaRosa et al.}
%\righthead{90~cm Image of Galactic Center}

\begin{document}

\title{A Wide Field 90~cm VLA Image of the Galactic Center Region}

%\author{T.N. LaRosa\altaffilmark{1}}
%\affil{Department of Biological and Physical Sciences,
%	Kennesaw State University, 1000 Chastain Rd., Kennesaw, GA
%	30144; ted@avatar.kennesaw.edu}

%\altaffiltext{1}{Navy-ASEE Summer Faculty Fellow, Naval Research 
%	Laboratory}

%\author{Namir E.~Kassim, T.~Joseph~W.~Lazio}
%\affil{Code~7213, Remote Sensing Division, Naval Research
%	Laboratory, Washington, DC 20375-5351;
%	kassim@rsd.nrl.navy.mil; lazio@rsd.nrl.navy.mil}

%\and

%\author{S.D. Hyman}
%\affil{Department of Physics, Sweet Briar College, Sweet Briar, VA
%	24595; hyman@sbc.edu}

\author{T.~N.~LaRosa, Namir E.~Kassim, T.~Joseph~W.~Lazio, \& S.~D.~Hyman}
\date{}
\maketitle

\begin{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\hbox{$^\circ$} $\times$ 5\hbox{$^\circ$} with an angular resolution
of 43\hbox{$^{\prime\prime}$}\ and has a rms sensitivity of $\approx$
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.
\end{abstract}

%\keywords {Galaxy:Center --- radio continuum}

\end{document}