Re: [alma-sw-ssr] Pipeline Requirements new version

[Mark Holdaway <mholdawa@nrao.edu>]

Other guys wrote:

> Bryan,
> 
> > this appears now excluded by hardware design 
> 
> too bad, EVLA looks more fun.
> 
> > unlikely in any case  that there are
> > enough sources to do that kind of calibration in a significant number of
> > projects.
> 
> Robert,
> 	you can check my numbers (maybe wrong ?)
> 
>  obsrms freq=40 antdiam=12 tsys=40 nants=60 bw=8000 inttime=.1 min
> => Rms Flux density:   0.142     mJy/beam in 6s.
> 
> Kellerman gives  N(S) = 60 S^{-1.5} Sr^{-1}  
> [at 5 GHz (?); I think Frazer had some better estimates at mm]
> 
> calc '60/.7e-3**1.5*2.1*2.1/3400/3400'
> =>  1.2 sources in a 2.1' beam above  5 x RMS in 6s.
>  
> 


I think you need to do better than this.  This is a detection of 5 sigma
of the entire array in 6 seconds, which means the noise on each visibility
will actually be sqrt(n(n-1)/2) = 42 times worse, or the signal is 1/8
sigma per baseline, which is equivalent to phase noise spinning around all
360 degrees.  In my simulations, 1 sigma detection per baseline is a good
rule of thumb, which puts you up by a factor of 8 in source flux.

	-M