For instructions on using the calculator, see Section 4.4 of the
Proposers Guide:
http://www.gb.nrao.edu/gbtprops/man/GBTpg.pdf.
Also look at section 7 for advice on writing your technical justification.
With the exception of the 26-40 GHz and MUSTANG receivers, continuum observations with GBT receivers are affected by 1/f noise, which is not taken into account by this calculator. These noise estimates are likely to be greatly underestimated. For information regarding 26-40GHz and MUSTANG performance, please refer to the GBT Observing guide. (http://www.gb.nrao.edu/gbtprops/obsman/GBTog.pdf).
Note that the "teff" or effective integration time is given by teff = (Ton * Toff)/(Ton + Toff)
where Ton is the time on-source and Toff is the time off-source.
New Instructions: Enter a Ton and Toff for all observing modes (usually Ton=Toff). If using in-band frequency switching or nodding, HALVE the resulting Ttotal and Teff.