Observations of the 327 MHz Deuterium Hyperfine Transition

Abstract

We report measurements of the 327 MHz line of deuterium for regions in the Galactic plane at 171°, 183°, and 195° longitude using an array of 24 stations of fixed phased-antenna elements. The anticenter region was observed using simultaneous multiple beams at each station over a period of just over 2 years from 2004 June to 2006 July. The average deuterium-to-hydrogen (D/H) ratio in the Galactic anticenter region derived from these observations is 21 ± 7 parts per million. The error is ±3 σ and includes the model-dependency error in conversion of the line amplitudes to the D/H ratio.