7 Summary

We have observed a 17 square-degree section (l, b) = ($178\hbox{$.\!\!^\circ$}0 \sim 186\hbox{$.\!\!^\circ$}0,\ 3\hbox{$.\!\!^\circ$}5 \sim 6\hbox{$.\!\!^\circ$}0$) of the Galactic Anticenter region in ¹²CO J=1-0 using the 3-mm SIS receiver on the 14-m telescope at Taeduk Radio Astronomy Observatory. A total of 7 000 spectra has been obtained with a grid spacing of 3'. The results of the observations are presented in the form of l-b and v-b contour maps. Molecular emission toward the Galactic Anticenter region is found to be very extended, and matches well with the FIR emission boundary. The radial velocity of the molecular gas is found to be within the range of $v_{\rm LSR} = -25 \sim +10$ km s^-1. We have also found several small clouds located at $l = 180^{\circ}$, $b=5^{\circ} \sim 6^{\circ}$ have $v_{\rm LSR}=-20$ km s^-1, which is quite anomalous in this direction. We have identified 30 individual clouds of the mapped region with an arbitrary threshold temperature using a cloud identification code within IRAF. Twelve subclouds are also identified with a higher threshold temperature from the largest cloud. There are several heating sources within the boundary of the region mapped. However, these are very localized, and do not seem to affect the surrounding dust on a large scale. Thus the bulk of the region lacks internal heating sources, and remains unheated. The primary heating source seems to be the general interstellar radiation field. The CO emission is well correlated with the FIR emission at 100 $\mu$m, which implies that there is little stray dust emission in the line of sight. The FIR emission and the ¹²CO integrated intensity relationship finds that the highest-possible value of $I_{100}/I_{\rm CO}$is $\sim 0.38$ (MJy sr^-1) (K km s^-1)^-1. This value is very close to that of normal dark clouds, thus the ratio of a substantial part of the mapped region is smaller than that of the dark clouds in the solar neighborhood.

Acknowledgements

Y.L. acknowledges the support for this work by Creative Research Fund 97-5400-003 of the Ministry of Science and Technology, Korea. We thanks to L. Allen and E. Bergin for their careful reading of the manuscript. We are also grateful to the referee, Dr. W.B. Burton, for his critical comments and kind suggestions.