[evlatests] your mail (Antenna Wrapping)

[Bryan Butler]

amended after some clarification from ken...


Bryan Butler wrote, On 3/8/10 09:01:
> 
> 
> David Harland wrote, On 3/8/10 08:49:
>> Yes, the OPT allows the user to provide wrap hints for each scan.
>> The scan's default is "No Preference"; the user may change this
>> to CW or CCW.
>>
>> The script generation process sets the wrap for every scan, using
>> -1 for CCW, +1 for CW, and 0 for no-preference.
>>
>> Questions:
>>
>> 1. Should we do as Ken suggested and suppress the
>> subarray.setWrap cmd if the user expressed no preference?
> 
> seems to me the thing to do is:
> 
> 1. do a subarray.setWrap(0) at the top of the script
> 2. only do a subarray.setWrap(I) on a scan where it was changed
>    from the default by the user in the OPT

3. on the subsequent scan, do a subarray.setWrap(0)


> 
> (this is probably what ken suggested...)
> 
> 
>> 2. Is there any harm in sending the same setWrap cmd
>> (eg, setWrap(-1)) on successive scans, as we do
>> currently?
> 
> there is no harm as long as the behavior is as i just described above 
> (i.e., the setWrap() has the same parameter as the last scan in which it 
> was specified).
> 
> 
> 
>>
>>
>> Bryan Butler wrote:
>>> we have always in the past left it up to observers to figure out 
>>> whether it is important to them or not.  we may not be able to 
>>> continue to do that, but for now that is the working model.
>>>
>>> there is no place that the wrap choice is made outside explicitly 
>>> setting it in the OPT.  if you don't set it (or set it explicitly to 
>>> "don't care") then the executor makes the decision about which way to 
>>> turn the antennas (i believe the algorithm is a direct copy of what 
>>> was done on the modcomps).
>>>
>>> in the future, we can do all sorts of fancy things.  in the future...
>>>
>>>     -bryan
>>>
>>>
>>> Steven T. Myers wrote, On 3/6/10 13:14:
>>>  
>>>> If we are to not have issues like this for routine dynamic observing,
>>>> then we at least need a way to make sure all antennas are in the same
>>>> wrap (whatever the executor or scheduler decides at the time the wrap
>>>> should be).  Where is it that the wrap choice (barring explict setting
>>>> in the OPT) is made?
>>>>
>>>> Things are usually more deterministic if you observe (ie. get on 
>>>> source at least) a source that is well south of the zenith so it it 
>>>> guaranteed to not be the ambiguous wrap zones, but I don't know if 
>>>> we want to go as far as recommending this to observers.
>>>>
>>>> In the longer term, if we don't go to full dwell-time scheduling, it 
>>>> might be prudent to have a parameter like "min_dwell_on_source" that 
>>>> is passed to the
>>>> scheduler so it can evaluate whether to execute a given schedule at 
>>>> a given
>>>> LST or not (the moral equivalent of running OBSERVE and seeing if 
>>>> you get
>>>> enough time on all the sources).  This at least might prevent the 
>>>> worst problems from slews and wrapping without requring the user to 
>>>> over-specify
>>>> start times.
>>>>
>>>>   -s
>>>>
>>>> On Fri, 5 Mar 2010, Bryan Butler wrote:
>>>>
>>>>   
>>>>> the OPT definitely allows one to set the wrap if desired.
>>>>>
>>>>>     -bryan
>>>>>
>>>>>
>>>>> Ken Sowinski wrote, On 3/5/10 17:45:
>>>>>     
>>>>>> On Fri, 5 Mar 2010, Vivek Dhawan wrote:
>>>>>>
>>>>>>       
>>>>>>> I just got done with a cursory look at the C55258.434 (AH1004)
>>>>>>> chunk, it looks good on the targets; but the flux cal scan 1331+3030
>>>>>>> is fringeless on 6 (otherwise good) antennas even though it is 
>>>>>>> 4:15 long
>>>>>>> and most antennas got 1:30 or so dwell time. This should be repeated
>>>>>>> with 1331 adequately scheduled, perhaps by moving it a bit later 
>>>>>>> in the
>>>>>>> schedule
>>>>>>>           
>>>>>> The fringeless antennas are clearly a wrap problem.  Whether
>>>>>> it is an observer oversight or a loss of information in
>>>>>> script generation I cannot tell.  The OPT allows wrap hints?
>>>>>> The scripts in question had every scan marked as 'dont-care-
>>>>>> about-wrap'.
>>>>>>
>>>>>> I suggest the script generator not include setWrap() calls
>>>>>> unless the observer has supplied an explcit hint to the OPT.
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>>>>>       
>>>> ------------------------------------------------------------------------- 
>>>>
>>>> |:| Steven T. Myers                      |:|  Tenured 
>>>> Astronomer       |:|
>>>> |:| National Radio Astronomy Observatory |:|  Ph:  (575) 
>>>> 835-7294      |:|
>>>> |:| P.O. Box O, Socorro, NM 87801        |:|  FAX: (575) 
>>>> 835-7027      |:|
>>>> |:| http://www.aoc.nrao.edu/~smyers      |:|  
>>>> smyers at nrao.edu          |:|
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>>>>
>>>>     
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