Loading data into Miriad: ATLOD

ATCA millimetre observations are loaded into Miriad in much the same fashion as centimetre data: task atlod is used.

One difference is that it is generally desirable to load both observing bands together, to allow joint calibration. A shortcoming of Miriad is that it is poor at handling multiple observing bands when the polarisation products differ between the bands. However the standard ATCA correlator configurations that combine narrowband and wideband observations generally do measure different polarisation products in the two bands. As polarimetry with the ATCA 3-mm system is not possible anyway, the simplest approach to ensuring the polarisation products of the two bands are the same is by discarding polarisation products that are not needed. The atlod option nopol causes atlod to discard any XY and YX products.

Typical inputs to atlod are:

ATLOD
in=2006-02-18_1234.C123	Input RPFITS file.
out=vela.uv	Output Miriad dataset.
options=nopol,birdie,reweight	Typical options used.

The birdie option for continuum data is used to discard edge channels and every second channel: for the continuum ATCA correlator configuration, successive channels are not independent and so there is no sensitivity penalty in discarding every second channel.