Hi Bertrand,

Right now, each user-added dataset has one possible label. I do
have plans to revise this so that you can select a label such as
"Object ID", "magnitude", perhaps other parameters (depending on
what the dataset contains.) Some description of how I intend to go
about this, and how it fits in with things such as getting lists
of objects in a given area, are at

http://www.projectpluto.com/future.htm#data_tables

In the meantime, one can edit the TDF for a given dataset and
look for the "text" entry, which tells Guide which columns should
be shown for the label. Change these to match up with the columns
chosen for the "mag" entry, and Guide will show that magnitude
data when labels are turned on.

This is a good, but not quite perfect, solution. A2.0, for
example, gives an R magnitude and/or a B magnitude for each star,
and you could easily reconfigure its definition (in 'gsc22.tdf')
to show one or the other magnitude. But you can't revise it to
show a V magnitude computed from R and B. Similarly, the
'loneos' data gives V magnitudes plus color data. Guide can
therefore show the V magnitude, but isn't quite bright enough
to realize that B, V, R, and/or I can be inferred from these.
(Unless I have a flash of inspiration, I expect to settle for "very
good" rather than "perfect" in this particular instance!)

-- Bill