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
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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.