[evlatests] WIDAR baselines, and time offsets

[Craig Walker]

The time IAT vs UTC offset is something that AIPS has had to deal with 
forever as VLBI data are in UT and VLA in IAT.  It is important to keep 
the leap second files up to date - which is easy to forget.  UVFIX does 
get used for both instruments.  I would not be surprised if whatever is 
deciding what sort of time is being used thinks the EVLA is the same as 
the VLA.

Cheers,

Craig


Eric Greisen wrote:
> Barry Clark wrote:
> 
>>>>    While making the comparisons noted above, I noticed that the two
>>>> databases are not precisely identical in their time axes.  Michael R.
>>>> noted some time delay between the arrays while the data were taken.  I
>>>> can confirm this, based on the index files of the two (supposedly)
>>>> parallel sets:  The VLA dataset is 32 seconds behind the WIDAR dataset.
>>>> In other words, all scans in the VLA dataset start and stop 32 seconds
>>>> later than those in the WIDAR dataset.
>>> I would expect 33 seconds.  Data from the VLA correlator is
>>> labelled in IAT, while data from Widar seems to be labelled
>>> in UTC.  I hope that the sign of IAT-UTC is consistent with
>>> what you describe.
>>>
>> Does uvfix know about this?
>>
> I don't know how, but the u,v,w from the corrected uvfix (for By sign 
> etc) gets answers very close to the original values - certainly not 34 
> seconds off.
> 
> Eric
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