Continuum surveys

In short, the points to clarify are: 

- the A/Tsys values of the European design: the 10500 is below the
  strawman design to which all original plans and calculations were
  based. To get the same sensitivity a four- fold integration time is
  needed. This is not a problem if the instrument has multiple FOV
  capabilities, so dedicating a beam for a long time to HI surveys 
  will not impair other observing programs.

- The FOV of the Karst design is too small, but here a focal plane
  array could help. We should say this so the designers know. This
  may then be a level 2-3 compliance.

- Continuum surveys: The China design definitely has too short a 
  maximum baseline. The European design could be stretched a bit.
  Maximum resolution is better than required to beat confusion. The
  highest frequency of the Europens design is in principle OK, pushing
  to higher frequencies is desired, partly to increase the resolution
  to better than 0.01 arcsec.  Both are level 3 compliant I think. 

Continuum surveys:

   China: FOV far too small. Longest baseline far too small. Spatial
          DNR lower than required.
  Europe: A/Tsys is too low but multiple beams compensate that. Highest
          frequency lower than other designs. Can perhaps be stretched 
          to few GHZ range. Much depends on confusion which should not
          be limiting if langest baseline indeed 2000-3000 km.
   India: unclear: need to know maximum baseline.
  Ozlens: OK? Need to study baseline distribution and spatial DNR 
   Ozcyl: OK? Need to study baseline distribution and spatial DNR 
     USA: OK? Need to study baseline distribution and spatial DNR 
  Canada: OK? Need to study baseline distribution and spatial DNR 

Source: Thijs van der Hulst, Chair of WG4

 Continuum surveys:
     China:  array too small, with no chance of making it larger, and
             the FOV is also too small. This makes the confusion at
             the lower frequencies unacceptable. The spatial DNR is
             also lower than most.
     Europe: upper frequency limit too low, so can't find the faintest
             flat-spectrum objects at high redshift. The upper
             baseline limit isn't too bad.
     India:  I don't regard the lower frequency bound as an issue
             here: although the maximum baseline isn't specified it
             should be available (somewhere!).
     Ozlens: The large FOV is a bonus, but without a detailed layout
             of the stations, the spatial DNR isn't clear
     Ozcyl:  The higher upper frequency limit is a bonus, but the
             spatial DNR isn't yet good enough, though it could be. I
             like the ability to work at higher frequencies because it
             gives the possibility of finding low-power, flat-spectrum,
             star-forming objects at moderate z.
     USA:    The lower frequency limit isn't much of an issue, and the
             spatial DNR is a minor issue. The high frequency limit is
             good.
     Canada: The large number of beams trades off against the FOV, and
             the extended frequency range is good. The spatial DNR is
             an issue for complicated fields.

Source: Mark Birkinshaw from WG4.