[daip] averaging time

[Eric Greisen]

Katherine Blundell wrote:
> Hi Eric,
> 
> Sorry for my radio silence (I managed to contract whooping cough…  not recommended).   I do hope that this finds you well.
> 
> I have a very basic AIPS question that I have managed to forget the answer to:  how do you find out what was the averaging time used when the data were correlated.    I vaguely thought that one could glean this from IMH, but seemingly not…   LISTR didn't seem to obviously give me this number.   
> 
> This question pertains to VLBA data, btw.
> 
> Sorry if this is a really basic question…
> 
> Cheers,
> 
> Katherine

Actually, this is not such a simple question.  Some data sets have an 
INT.TIME random parameter (like time, baseline, u, v, w) which can be 
displayed by PRTUV with DPARM(6) = 1.  This is however not the 
integration time at correlation but the current averaging time.

VLB data sets may have a CQ table.  If you have such a thing, PRTAB will 
show a column which I suspect is the integration time at correlation. 
I've been after the JVLA people to write a CQ table with no luck.  Its 
main use is to show the channel width at correlation.  If there has been 
frequency averaging after correlation, then amplitudes need correcting 
for the delay error, but one has to know the correlation bandwidth since 
that part of the bandwidth does not suffer a loss due to the delay.

Stay well

Eric