The UV Tables in the original GDFV1 data format, created in 1989, handled visibilities and their required associated data parameters in a very similar way as the UVFITS data format used to export data from the VLA at that epoch. A visibility consisted in
The 7 (daps) were real numbers. As Plateau de Bure is a 2-D array with small field of view, w was most often replaced by the scan number scan for debugging purpose. The number of channels was simply derived from the visibility size with
With further developments coming on, such as polarization, on-the-fly mosaicking, multi-source UVFITS files from CASA,... this scheme was becoming far too constraining. In addition, UV data sets could readily exceed the 2 GByte size limit of the GDFV1 data format. We thus decided to take advantage of the changes required to handle large data sets to implement a more flexible UV data format.