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

[Harvey Liszt]

I of course can give you as many of the predicted-to-be-strong-at-100 
GHz ATNF sources as you want, in the format of the existing .py script 
or whatever.

H.
-----------------------------

On 5/10/10 4:39 PM, 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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>
>


-- 
Harvey S. Liszt                       work:+1 434.296.0344 fax 0278
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