[mmaimcal] Re: [alma-sw-ssr] question about frequency/band switching speeds and rates

[Bryan Butler]

the usual rule-of-thumb is 2-4 samples per FWHM - at least that is what 
we have always been working with.  the 15 msec i sent out earlier uses 2 
samples per 950 GHz FWHM.  the reconstruction all comes out in the wash 
in the mosaicing.

	-bryan


On 2/4/05 15:23, Ed Fomalont wrote:
> Hi Bryan,
> 
>    Of course you are correct.  Maybe the limiting time for phase center 
> updating is
> governed by the change of primary beam on the sky.  So, the phase center 
> update
> should occur less than the change of the pointing by 0.1 beam (probably 
> smaller
> for high dynamic range work).
> 
> Ed
> 
> Bryan Butler wrote:
> 
>>
>> i don't follow this.  why do you care what the magnitude of the phase 
>> center change is between discrete pointings, as long as the instrument 
>> is stable for each "pointing"?  it's just like "point-and-shoot" 
>> mosaicing, just moving the primary beams of the antennas while you do 
>> it, and going fairly fast...  now, if there is an unknown phase shift 
>> across the PB, then there would be trouble, but last i knew mark had 
>> worked out a way to calibrate that out...
>>
>>     -bryan
>>
>>
>> On 2/4/05 13:08, Ed Fomalont wrote:
>>
>>> Hello all,
>>>
>>> 1.  Discrete changing of the phasing while doing an OTF is okay, as
>>> long as the phase change for a source in the beam doesn't change by
>>> more than about 10 deg between phase center updates - whatever
>>> time increment this is for the highest frequency and longest baseline.
>>
>>