Evidence for the existence of a low-velocity molecular cloud near Sgr A.

Observations of the 1 11-1 10 line of H2CO (rest frequency 4829.66 MHz) toward the galactic center region show near-zero radial velocity in the direction of Sgr A. Over the velocity range -14.5 to 7.4 km/sec there is an absorbing cloud extending over the continuum with a fairly uniform optical depth of 0.04-0.08. There is a compact region with angular dimensions to half-intensity points of 5-10 arc min. It is centered on the ridge of thermal continuum emission extending north of Sgr A, close to where continuum surveys at higher angular resolution show a continuum maximum. The projected H2CO density is 7 x 10 to the 13th/sq cm. The evidence suggests that the absorption occurs in an H II region-molecular cloud complex.