[evlatests] Sensitivity Equation

[Bryan Butler]

you might also see: http://adsabs.harvard.edu/abs/1989AJ.....98.1112K 
for gory details.

or anantha's treatment: 
http://adsabs.harvard.edu/abs/1991ASPC...19....6A and 
http://adsabs.harvard.edu/abs/1989ASPC....6..431A (the second one is the 
SIRA chapter).

	-bryan


Rick Perley wrote, On 11/23/11 8:52 AM:
>      In yesterday's 'Stokes V' discussion, I mentioned the sensitivity
> equation, which includes the effects of 'self-noise'.
>
>      The nicest form of the equation is in the article by Joan and Craig
> in the 'Synthesis Imaging' book, Eq. 10 in Chapter 9.   It can be
> written, for a single correlator (real or imaginary part of a single
> complex correlator), and a point source as:
>
>      sigma = sqrt(A)/(eta.sqrt(B))
>
>      where:
>
>      A = 2.S_t^2 + 2.S_t.S_e + S_e^2
>      B = 2.BW.T
>      eta = system (correlator, electronics) efficiency.
>
>      and
>
>      S_t = source flux density (Jy)
>      S_e = antenna SEFD (Jy)
>      BW = bandwidth (Hz)
>      T = visibility integration time (sec)
>
>      If the source is resolved, then a modification is needed to the
> first term in A:
>      Replace
>      2.S_t^2
>      with
>      S_c^2 + S_t^2,
>
>      where S_c is the correlated flux on the baseline of interest.  Keep
> in mind that S_c and S_t will be different between the real an imaginary
> parts, depending on where the source is.  For a properly phased array,
> and a point source, these terms will only apply to the real part.
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