Stacking of SKA data: comparing uv-plane and image-plane stacking
  Stacking as a tool for studying objects that are not individually detected is
becoming popular even for radio interferometric data, and will be widely used
in the SKA era. Stacking is typically done using imaged data rather than
directly using the visibilities (the uv-data). We have investigated and
developed a novel algorithm to do stacking using the uv-data. We have performed
exten- sive simulations comparing to image-stacking, and summarize the results
of these simulations. Furthermore, we disuss the implications in light of the
vast data volume produced by the SKA. Having access to the uv-stacked data
provides a great advantage, as it allows the possibility to properly analyse
the result with respect to calibration artifacts as well as source properties
such as size. For SKA the main challenge lies in archiving the uv-data. For
purposes of robust stacking analysis, it would be strongly desirable to either
keep the calibrated uv-data at least in an aver- age form, or implement a
stacking queue where stacking positions could be provided prior to the
observations and the uv-stacking is done almost in real time.
