[evlatests] your mail (Antenna Wrapping)

[David Harland]

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?

2. Is there any harm in sending the same setWrap cmd
(eg, setWrap(-1)) on successive scans, as we do
currently?


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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