Darrel Emerson, 10/23/97
The following show the relative frequency occupancy of observing at the NRAO 12 M Telescope at Kitt Peak, from April 1994 to December 1996. The statistics were calculated on the basis of "scans" rather than strictly observing time, but the difference should be minimal.
These are statistical summaries, binned every 100 MHz. For the sky frequency of each observed scan, bins +/-300 MHz of that frequency, corresponding to the telescope i.f. bandwidth, were incremented by one count. Finally the bins were normalised to give the fraction of observing time spent at that frequency.
Comments: Note that there is a bias towards lower frequencies in the plots, simply because of the atmosphere at Kitt Peak, which will influence the observers' choice of frequency. In addition, the 1-mm receivers at the 12 M are not normally made available throughout the observing season, because of expected opacities at certain times of year. The 3-mm receivers are normally available throughout the season.
It is interesting to see the low-frequency tail on the 115 GHz CO line, presumably because of observations of red-shifted 12CO.
These plots were produced by Tom Folkers, from 12 M archival data.
Fig 1: The relative percentage occupancy of frequencies
Fig 2: Relative occupancy, vertical scale increased.
Fig 3: Relative occupancy, vertical scale further increased.
Fig 4: A "yes or no" plot of frequency occupancy.