[daip] Re: POSSM with BPARM normalisation

[R. Niruj Mohan]

Hello,

I am not sure I understand fully what is going on, and
what the fix is going to be.
However, is there a temporary fix I can perform to
carry on with my data ? Since I have 15 channels, I
really cant afford to throw away end channels (this is
a line obs) and to make things worse, there are two LO
settings to cover the full line ! 

I was wondering if I SPLIT my BPcal data with
SMOOTH=1,0 and then apply BPASS, and view with POSSM,
all with SMOOTH=0, things should be okay ? The
resultant spectrum of my BPcal is much better but
still has some wierd stuff. And a second BPASS after
applying the first BP doesnt help much (which probably
means non-closure somewhere, I guess). I am attaching
the second BP table (all on my BPcal). Should this
method be free of the error you had mentioned ?

regards
Niruj


 --- Eric Greisen <egreisen at nrao.edu> a écrit : 
> Thank you - we do have an error.
> 
> The DATGET routine smooths the data BEFORE applying
> the BP
> calibration.  Therefore, the edge channel would be
> very enhanced by
> adding it partly to channel 14 (in your case) and
> then scaled way up
> by the BP cal which would have been correct for
> channel 15 with no
> smoothing but which applies about a factor of >2
> correction.
> 
> Smoothing the BP cal in BPASS produces a BP table
> that is incorrect
> fpr unsmoothed data and that is not an aips error.
> 
> But this thought makes it clear that in the second
> case one does want
> to smooth the data before the BP cal so that the
> smoothed BP cal
> applies to the smoothed data, while in the former
> case one wants to
> apply the unsmoothed BP cal and then smooth.  I see
> new options in
> SMOOTH coming (uh oh!)  This will take a while since
> it is pretty
> fundamental.
> 
> Eric Greisen
>  


	

	
		
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