Dead dipoles

Each MWA tile has 16 "bowties", and each bowtie is made up of two dipoles (one X, one Y). We refer to a "dead" dipole as one that is not functioning correctly (hopefully not receiving any power at all). This information is used in generating beam responses as part of modelling visibilities. The more accurate the visibilities, the better that calibration performs, so it is important to account for dead dipoles if possible.

Beam responses are generated with hyperbeam and dead dipole information is encoded as a "dipole gain" of 1 ("alive") or 0 ("dead"). It is possible to supply other values for dipole gains with a "DipAmps" column; see the metafits page.

For the relevant functions, dead dipole information can be ignored by supplying a flag --unity-dipole-gains. This sets all dipole gains to 1.

At the time of writing, dead dipole information is only supplied by a metafits file.

See this page for more info on dipole ordering.

In the image below, you can see the 12th Y dipole is dead for "Tile022". All other dipoles are "alive".