[evlatests] your mail (Antenna Wrapping)

[Bryan Butler]

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

(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) 
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>>> |:| http://www.aoc.nrao.edu/~smyers      |:|  
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>>>
>>>     
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