Appendix: GBT Gain and sensitivity.

This table lists typical system temperatures (Tsys), gains, and aperture efficiencies measured at high elevation in good weather. There is virtually no change in efficiency with elevation for frequencies of 6 GHz and lower.

Also listed are rms flux density levels for continuum observations with 80 MHz bandwidth (column 6), and various spectral line configurations (columns 7-10), calculated from the above formulas for an on-source integration time of 60 seconds.

The active surface should be used for frequencies of 8 Ghz and higher.