Spectral-Line Observing

We will consider the rms, $\sigma_{{\rm T}}$(K), for observations with a receiver of system temperature, T$_{sys}$, frequency resolution, $\beta$ per polarization, and total integration time per observing cycle, $\tau$. Note that $\beta = 1.2B/N$, where $B$ is the total bandwidth of the spectrometer per polarization, and $N$ is the number of independent points in the computed spectrum (e.g. the number of spectrometer channels for an unsmoothed spectrum.) If the spectrum has been Hanning smoothed, then the effective frequency resolution is broadened by a factor of about 1.67. The sensitivity calculations given below represent the analog case, and it should be remembered that 9-level operation of our spectrometer achieves 96% of the signal-to-noise of analog correlation, whereas 3-level operation achieves 81%. For the following observing modes, the theoretical sensitivities are;

Robert Minchin 2017-10-30