Masers are the radio wave equivalent of lasers, and they occur naturally in molecules with metastable energy levels; water vapor also produces natural maser emission.
OH masers commonly occur in interacting galaxies, and so it has been difficult to identify unambiguously which of the galaxies is the maser source. In addition, many of the early claims of OH maser detection were never confirmed, or the discovery spectrum was never published.
I'm involved in a project to use the Jansky VLA to observe a sample of OH maser galaxies. The new WIDAR correlator allows us to search a wider range of the radio spectrum. The OH molecule has four spectral lines in the spectral window we selected, although only two of the lines show maser emission strong enough to detect.
The goals of this project are to confirm the presence of OH maser emission and to determine the location of the masers to ~ 1 arcsecond accuracy (1 arcsecond = 1/3600th of a degree). This is my first time using the upgraded VLA, and the spectrum shown above represents the first detection from this project. The maser appears as a pair of closely spaced peaks in the spectrum. For reference, this OH maser galaxy is located at a distance of roughly 3.2 billion light years.
