Calibration Strategies
----------------------

For best flux density calibration of spectra, we recommended that you should observe continuum flux
density calibration sources at least once during an observing session. To do this, do a Peak/Focus
on the calibrator, followed by an observation in the same spectral line setup used for the program 
sources. This will give the relation of flux density to antenna temperature as a function of 
frequency that can be applied to the program spectra.

Of course, there may be other outstanding reasons to perform calibration observations more often.
If you have concerns over how often you should observe a calibrator you should get into contact 
with your GBT project friend.

Flux density histories for many of the bright 3mm point sources can be found in the `ALMA Calibrator
Source Catalogue <https://almascience.eso.org/sc/>`__.