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Sensitivity and total integration time

     

Spectroscopists may need to consider separately two different sensitivities--the sensitivity to spectral features in the individual line channels and the accuracy with which the continuum can be estimated from the line-free channels. The need for individual channel sensitivity normally dominates, however. The calculation uses Equation 3, with tex2html_wrap_inline2609 replacing tex2html_wrap_inline2313 . It may also be appropriate to express the sensitivity in terms of brightness temperature by converting from mJy per beam area to temperature units assuming a Gaussian beam of area tex2html_wrap_inline2645 .

Use of narrow channel bandwidths tex2html_wrap_inline2609 often implies that sensitivity, rather than u-v coverage, considerations determine tex2html_wrap_inline2261 for high-resolution synthesis spectroscopy, so that observations >12 hours long may be needed. Spectroscopic observations may also need long integrations on the calibration sources to achieve enough sensitivity.



abridle@nrao.edu
Thu Jul 11 16:26:53 EDT 1996