Active Surface Strategies
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If you are observing at a frequency of 8 GHz or higher then you should use the Active Surface (AS).
At frequencies below 8 GHz the AS does not provide any improvements to the efficiency of the GBT.
Due to RFI considerations the AS may be turned off for lower frequency observations.

.. note:: 

    You do not need to do anything to turn on or off the use of the AS. The GBT operator performs these tasks.