Interferometric Observations of Formaldehyde Absorption in Front of Strong Galactic Sources

摘要

Observations have been made of formaldehyde absorption at 4830 MHz in front of Sgr A, Sgr B2, W3, NGC 2024, W31, W33, W43, W49A and W51. The California Institute of Technology interferometer, consisting of two 90-foot paraboloids, was used to synthesize a beam of 40 x 60 sec(delta - l) where delta is the source declination and l = 38 degrees. The main absorption features show variations of optical depth over the sources but there is no significant clumping. (Author)