[daip] aips question

[Eric Greisen]

koneil at nrao.edu wrote:
> Eric,
> 
> I have a problem reducing some data which I am hoping you (or someone 
> you desingate:) can help with.  i have spectral line data where I 
> screwed up and the source has a channel speration twice as big as the 
> calibrator does, for the spectral line data (24.414 kHz vs. 48.828 
> kHz).  This has resulted in two separate files being created for the 
> project.
> 
> To reduce the data, it seems to me I need to combine the source & 
> calibrator files.  For the ch0 data this is easy, and dbcon + indexr 
> does the trick.  But when i try and combine the line data, i get the error:
> "DBCON1: MULTI-FREQUENCY DATA BASES INCOMPATABLE".  I  am guessing this 
> is due to the difference in the channel separations.  But I cannot 
> figure out how to decimate the source line data or otherwise combine the 
> data.  Similarly I
> do not understand how to calibrate the bandpass without having the 
> calibrator and source within the same file  - when I try I get the error 
> "BPASS1: LINE & CHANNEL 0 FILES HAVE DIFFERENT NO. VIS. POINTS".
> 
> Do you know of a solution to this problem?

Are you setting IN3NAME et al?  I would recommend dividing by the 
locally determined channel 0 under control of BPASSP(5).  I suspect that 
you can run BPASS on the cal file and copy the BP table to the source 
file and then hope that the bandpass shapes at the 2 channel widths are 
similar.  I am assuming that you have the same number of channels in 
each, just a different channel width.  If that is not the case, then one 
must do something better - and it would help if you told me the details 
(e.g. the IMHEAD of the 2 UV files).

Eric Greisen