[daip] Frequency coordinates(31DEC05 vs 31DEC04)

[Eric Greisen]

The FQ table is giving IMAGR wrong information.  It states that the
frequency increment is positive.  I also received an e-mail from a
user who has both sidebands in her data and the increment for both is
shown as positive.  AIPS has never used the sideband code to change
the stated frequency increment in the FQ table.  This is because the
data may be lower sideband but reversed in order so that the increment
is positive for both bands - the VLBA does this.  The FQ table is used
by IMAGR where ISPEC deals with an image and there is no FQ table.

We have not changed any aspect of this between 31DEC00 I suspect and
the present.  We have fixed how DBCON, SPLIT and SPLAT handel things
when there is more than one FQ and the frequency increments have
opposite sign.  We did not handle them correctly until the fix we just
put in 31DEC06.

It will be very difficult to check for differences in how 31DEC04 and
31DEC05 handle frequencies and I do not expect there to be any - while
there will be many other differences.  Are you claiming that on the
very same data set, IMAGR now does the "wrong" thing whereas it used
to do the "correct" thing (i.e. ignore the FQ table)?

Eric Greisen