iraf.net

Does anyone know this? If I have only one filter and prepare the observations file and configuration file the right way, and then run fitparam to get the zero point, then what would the output be? It normally gives a catalog of stars and then the magnitudes in each filter but like the Landolt catalog it only gives the V magnitude directly, the rest can be found by adding and subtracting the appropriate columns, say U=column (U- + column (B-V)+ column V.But what happens if I have only one filter, say, U? What's the output format then? Also, if I have filters V and U, but am missing B, then how would I get the U magnitude from the instrument magnitude catalog created here? I can't very well do U=column (U- + column (B-V)+ column V because columns (U- and (B-V) should be INDEF. So what do I do? HOw do I get to my instrumental magnitudes from the catalog alone? Is this described somewhere? Not in the help files, I took a quick look.Any information will be greatly appreciated, I'm quite confused on the matter.

If you have only one filter, you can not transform your "internal" system data
to the "standard" (catalog) system.