The FORTH program for spectral line observing

The 11-m telescope of the National Radio Astronomy Observatory (NRAO) on Kitt Peak is extensively used for spectral-line observing at millimeter wavelengths. The computers that control the telescope and receiver have been programmed in FORTH. This language provides an extensive vocabulary for the astronomer to use to control his observation and reduce his data. Here we summarize the capabilities provided by the most common words of this vocabulary--capabilities ranging from telescope tracking patterns to fitting line profiles. It is noteworthy that the number of words required for sophisticated observing is large and growing.