### Current assumptions and limitations

GILDAS works in the LSR velocity frame and has limited polarization capabilities ( IMAGER can only process one polarization state at a time, see Section for details). Thus the casagildas() - fits_to_uvt sequence makes several assumptions:

- FDM (Frequency Division Mode) spectral windows are converted to LSR frame using the mstransform tool
- TDM (Time Division Mode) spectral windows, which have low spectral resolution (15 MHz), are assumed to be pure continuum data, and remain in the default frame of the original measurement set.
- The conversion from UVFITS to uv tables assumes that the data is unpolarized4, and merges the initial polarization states in an optimal way from the signal to noise point of view (i.e. using the respective weights of the two parallel hand states).
- casagildas() takes the same input parameters as the listobs() facility. Source and/or spectral window selection can thus be made by the user at this stage
- casagildas() takes the same input parameters as the mstransform() facility. Time integration may be done at this stage, but this may limit the performance of self-calibration at a later stage.