[daip] IBLED

[Phil Diamond]

I am reducing a large VLBA dataset on SiO masers in Orion. I am using
31Dec01 under Linux. The datset consists of two IFs, 512 channels and
~770000 visibilities. After some calibration I have run AVSPC on the data
to produce one channel, keeping the two IFS. I fed this dataset to IBLED,
averaging for 10 seconds from the 2.097 correlator integration time.

I can display and edit IF1 with no problem. However, when I switch to IF2
within IBLED the amplitudes contain what looks like strong, time variable
interference on all baselines. This is not real. Plotting the IF2 data
with VPLOT shows no sign of this. Rerunning IBLED and selecting IF2 at
input reveals very clean looking data. The problem arises when switching
between IFs within IBLED. I have never seen this problem before. However,
I have never reduced data from such a large file before.

Claire Chandler could probably provide a similar file for testing IBLED
rather than trying to ship over my data.

- Phil

------------------------------------------------------------------------------
Philip Diamond                            | pdiamond at jb.man.ac.uk
Director, MERLIN & VLBI National Facility |
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