The large scale survey of the Galactic center region in the
(
) transition line presented here reveals
several interesting aspects of the molecular gas near the Galactic
center.
survey
demonstrate that there are great differences in the distribution
of the optically thin emission and the
emission, generally assumed to be
optically thick.
emission, the
emission shows much more contrast. This
results, as will be invesigated in detail in Paper II, in line
intensity ratios of to
which are rather high and variable
compared to ratios found in the Galactic disk.
. Also confirmed is the displacement by
several scale heights above (SgrD, Clump 2) or below (SgrC)
the b = 0
-plane.
) is not only
rather strong in the Galactic Center but also rather extended,
though more confined than . In particular the feature
HNCO-1.65-0.0 is of interest because it has no clear counterpart
in CO.
and the
emission will be discussed in Paper II (Dahmen et al.
1997). In addition, the physical and kinematic conditions of the
Galactic center region will be discussed.
Acknowledgements
We acknowledge the financial support of a Bennigsen-Foerder research prize awarded to one of us (RM) by the Land Nordrhein-Westfalen, which was essential to carry out this work. Additional financial support for this project was awarded to two us (TLW and LB) by the Commission of the European Communities (contract CI1*-CT93-0332). LB and JM acknowledge support from FONDECYT Grant 1950627. We thank Prof. R. Wielebinski for the generous loan of the AOS, the staff of the Digital Laboratory of the MPIfR for the great support in maintaining the AOS, the people of the Departamento de Astronomía of the Universidad de Chile for the operation of the 1.2 m SMWT at CTIO, and the staff of the Cerro Tololo Interamerican Observatory (CTIO), in particular the engineers G. Arriagada and M. Lazo who were very helpful in solving technical problems. C. Henkel contributed great support during the preparation phase of this project. K.I. Uchida kindly gave us access to the Bell Labs 12 data before publication. Not at least, we very much thank all additional observers of this project who have all stayed on Cerro Tololo at least for two and mostly for three weeks, namely C. Lemme, D. Muders, H. Wiesemeyer, F. Wyrowski, T. Megeath, M. Petr, S. Richter, A. Grunert, S. Kohle, and D. Fischer. Finally, we thank the referee J. Bally for helpful comments.