-------- Original Message --------
Subject: Re: [Bispud-pipeline-list] Toy model for negative TQ
Date: Tue, 05 Mar 2013 19:04:06 -0500
From: John Kovac <jmkovac(a)cfa.harvard.edu>
To: Chao-Lin Kuo <clkuo(a)stanford.edu>
CC: bispud-pipeline-list <bispud-pipeline-list(a)lists.fas.harvard.edu>
This is the Italian paper we made reference to on the telecon today.
http://www.sat.ltu.se/members/viju/publication/cmb/mnr_11464.pdf
I remain skeptical that this effect could produce a signal that evades
temporal jackknives, but I strongly encourage people to think about it.
Regardless, this could be the explanation for the large-scale average
polarization signal that appears to align with the prevailing wind.
Exploring this signal in B1, B2, and Keck could certainly be
scientifically interesting (i.e. eventually publishable) on its own
merits, even if it isn't the problem we're dealing with in B2.
J
On 3/5/13 6:39 PM, Chao-Lin Kuo wrote:
>> Negative TQ seems strong and convincing to me. Like I said in
>> the telecon I don't think it is consistent with ground screen reflections
>> though. The sky signal reflected into the telescope is not visible to
>> the main beam so why would there be any correlation, positive or negative?
> Ok, If the reflected signal generates T , which is then polarized by the ground screen, that could generate a TQ. Sarah is reading through Denis' thesis to see whether this has the right sign.
>
>
>
>
>> However if a big blob of cloud at low elevation intercepts the
>> far side lobe, it could introduce both a T signal and a Q signal that
>> would be anti-correlated. See the attached cartoon.
>>
>> This can also break the positive-negative symmetry: most clouds have
>> crystals align vertically. So there is no fluctuation to 'cancel' the
>> negative correlation.
>>
>> Looking at
>>
>> http://bmode.caltech.edu/~spuder/analysis_logbook/analysis/20130304_azmaps/
>>
>> section 3, we know the negative correlation isn't perfect though, before
>> ground subtraction.
>>
>> Chao-Lin
>>
>>
>> <TQ_from_cloud.gif>
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--
___________________________________________________________________
John Kovac jmkovac(a)cfa.harvard.edu
Assistant Professor, Astronomy and Physics, Harvard University
160 Concord Ave rm 310, Cambridge MA 02138, 617-496-0611
-------- Original Message --------
Subject: [Bispud-pipeline-list] Toy model for negative TQ
Date: Tue, 5 Mar 2013 12:44:39 -0800 (PST)
From: Chao-Lin Kuo <clkuo(a)stanford.edu>
To: bispud-pipeline-list <bispud-pipeline-list(a)lists.fas.harvard.edu>
Negative TQ seems strong and convincing to me. Like I said in
the telecon I don't think it is consistent with ground screen reflections
though. The sky signal reflected into the telescope is not visible to
the main beam so why would there be any correlation, positive or negative?
However if a big blob of cloud at low elevation intercepts the
far side lobe, it could introduce both a T signal and a Q signal that
would be anti-correlated. See the attached cartoon.
This can also break the positive-negative symmetry: most clouds have
crystals align vertically. So there is no fluctuation to 'cancel' the
negative correlation.
Looking at
http://bmode.caltech.edu/~spuder/analysis_logbook/analysis/20130304_azmaps/
section 3, we know the negative correlation isn't perfect though, before
ground subtraction.
Chao-Lin
