[mmaimcal] [Almasci_chile] Some thoughts on ALMA calibrator sources

[Darrel Emerson]

Please consider me for the team too.  Thanks!

         Cheers,
                Darrel.

Al Wootten wrote:
> Count me in!
> 
> Al
> 
> Stuartt Corder wrote:
>> Hi all,
>>
>> I think we are collecting enough information that we should call another 
>> amplitude calibration team meeting and discuss some of the details that 
>> people have provided along this thread.  I think the other thing to 
>> start talking about is how to *start* approaching this with ALMA.  I 
>> have recently developed a script that will do a dip, 
>> planet/asteroid/moon observation and then start through the list of 
>> quasars.  The current catalog has some structures (Al mentioned this 
>> earlier, sourceCatalog.py) for predicting flux at various bands 
>> (basically a spectral slope and 3 mm flux).  Of course this is all 
>> defaulted to flat spectrum at this point but the structure exists.  
>> However, the tools in sourceCat are designed for catalogs with <= a few 
>> hundred sources (i.e., they have rather unintelligent source searching 
>> routines..I can say this because I wrote them).  If we are really going 
>> to start fashioning a catalog of thousands, we need to have a separate 
>> catalog that includes some information (like last observed date) so we 
>> can add options to observe ones with dates older than X many days.  We 
>> also need some sorting routines because we will want to do parts of the 
>> sky (this isn't hard, someone needs to do it, the most likely candidate 
>> for that is me). 
>>
>> Thanks for all the comments.  The ampcal team is supposed to do both 
>> these sorts of studies and commission the system for accurate 
>> measurement of the flux scales.  Right now I many of you are not on that 
>> team.  If you would like to be included (specifically Al, Satoki, and 
>> Anita since your involvement is both relevant and ALMA-centric) let me 
>> know and I'll put you on the team distribution.  Rudy, no worries on 
>> you, you are already on it.
>>
>> Stuartt
>>> Dear Al and all,
>>>
>>> In case of SMA southern calibrator sources (which cannot be observed from
>>> NMA, OVRO, BIMA, or PdBI), we first collect the possible calibrator sources
>>> from the ATCA & VLA calibrator source catalogs (+ some VLBI calibrator
>>> sources).  If there are two frequency information, we estimated 230 GHz
>>> flux from those, but if not, we used typical spectra index (-0.8?  I
>>> forgot...), and estimated 230 GHz flux.  We then put some lower limit in
>>> estimated flux at 230 GHz (> 0.5 Jy?  Again I forgot...) and made a survey
>>> catalog, and then we actually observed.  If it was bright (>0.5 Jy?), we
>>> put the source in the official SMA catalog.  Some sources observed several
>>> times, but some only observed once at the survey.  So, it is not perfect,
>>> but the number of calibrator sources increased.
>>>
>>> Just my two cents.
>>>
>>> Cheers,
>>> Satoki
>>>
>>>
>>>
>>> Al Wootten :
>>>   
>>>> Hi folks
>>>>
>>>> It is a good time to consider this subject again.
>>>>
>>>> As we discussed at the Dec 09 Sci IPT meeting the SPT survey sources 
>>>> presented in:
>>>> http://arxiv.org/abs/0912.2338
>>>> support the predictions made in the numerous ALMA memos on the subject. 
>>>>   The area surveyed was very limited but of course this is a dynamic 
>>>> field with Planck and the SPT still exploring.
>>>>
>>>> I think sourceCatalog.py is a derivative of SMA and other catalogs but 
>>>> ALMA is reaching the point where it can contribute usefully to compendia.
>>>>
>>>> There was a plan at some point for a comprehensive EVLA/VLB/ALMA catalog 
>>>> but I do not know where that stands or whether ALMA needs an independent 
>>>> initiative.  Temporal measurements are critical--certain SBs run in 
>>>> March used calibrators which had worked well for the SMA but whose flux 
>>>> had faded to uselessness even for the more sensitive ALMA 3-antenna array.
>>>>
>>>> Clear skies,
>>>> Al
>>>>
>>>> Harvey Liszt wrote:
>>>>     
>>>>> Something to keep boredom at bay. Attached.
>>>>>
>>>>> H
>>>>>
>>>>>
>>>>> ------------------------------------------------------------------------
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>>
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