Nominal ARISE sensitivity

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Nominal ARISE sensitivity

The overall sensitivity of a radio telescope can be characterized by the ``System Equivalent Flux Density'' (SEFD) in Jy, where
equation15
Here, tex2html_wrap_inline358 is the system temperature in Kelvin and tex2html_wrap_inline360 is the effective area of the antenna in square meters. The r.m.s. noise on the interferometer baseline between ARISE (telescope ``A'') and ground radio telescope ``g'' is then denoted by
equation20
Here, tex2html_wrap_inline366 is an efficiency factor due to sampling and correlation, tex2html_wrap_inline368 is the observing bandwidth, and tex2html_wrap_inline370 is the integration time. A typical fringe-detection threshold is tex2html_wrap_inline372.

We assume a fixed data rate of 8 Gbit sectex2html_wrap_inline346 for ARISE. Nominal values for 2-bit sampling at 86 GHz are tex2html_wrap_inline376, tex2html_wrap_inline378 GHz, and tex2html_wrap_inline380 sec. (The sensitivity for 1-bit sampling differs by only 2% from 2-bit sampling, under the assumption of a fixed data rate.) Current baseline values for the 25-meter ARISE telescope are an aperture efficiency of only 8% and a system temperature of 45 K, corresponding to tex2html_wrap_inline382 Jy. For a 25-meter VLBA telescope, conservative estimates are an aperture efficiency of 0.20 and a system temperature of 150 K, giving tex2html_wrap_inline384 = 4200 Jy. (VLBA performance is likely to be somewhat better by 2008, particularly in the aperture efficiency.) If we assume 2-bit sampling and convert the bandwidth tex2html_wrap_inline368 to the data rate DR, the detection threshold is given by
equation31

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