------------------------------------------------------------------------
From: ZADEH@OSSENU.ASTRO.NWU.EDU
Date: Fri, 14 May 1999 13:32:02 -0500 (CDT)
To: gcnews@aoc.nrao.edu
Subject: paper
X-Keywords: 

%astro-ph/9904142
\title{The Position of Sgr A$^*$ at the Galactic Center}
\author{F. Yusef-Zadeh, D. Choate, W. Cotton}
\begin{abstract}
     The absolute position of the compact radio source at the dynamical center 
of the Galaxy, Sgr A$^*$,
     was known only to an accuracy of $0.2''$ in spite of its accurate location 
with respect to near-IR
     stellar sources to within 30 milliarcsecond (mas). To remedy this poor 
positional accuracy, we have
     selected 15 high-resolution, high-frequency VLA observations of Sgr A$^*$ 
carried out in the last 13
     years and determined the weighted average position with the average epoch 
1992.4 to be at $\alpha$,
     $\delta$[1950] = $17^{\rm h} 42^{\rm m}$ 29\dsec3076$\pm0.0007$, $-28^\circ 
59^\prime
     18.484\pm0.014^{\prime\prime}$, or $\alpha$, $\delta $[2000] = $17^{\rm h} 
45^{\rm m}$
     40\dsec0383$\pm0.0007$, $-29^\circ 00^\prime 28.069\pm0.014^{\prime\prime}$ 
which agrees with
     earlier published values to within the $0.2''$ error bars of the earlier 
measurements. An accurate
     absolute position of Sgr A$^*$ can be useful for its identification with 
sources at other wavelengths,
     particularly, in soft and hard X-rays with implications for the models of a 
massive black hole at the
     Galactic center. 
\end{abstract}

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