High Frequency Observing Strategies ----------------------------------- When observing at frequencies above 10 GHz you should be aware that additional calibration measurements may be necessary. The telescope efficiency can become elevation dependent, atmospheric opacities are important and the opacities can be time variable. You should contact your GBT project friend to discuss these issues. All the GBT high frequency receivers have at least two beams (pixels) on the sky. You should make use of both of these during your observations if possible. For example, if you are doing position switched observations and your source is not extended then you can use the :func:`Nod() ` procedure to observe.