Summary of dicussion during chop-nod analysis telecon of Jan 16, 2008

Hiroko, Lero, Mike, John, Giles, Martin

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M82 analysis:

Lero has looked at four M82 dithers on 4/28 (UT).  Overall the data do not 
agree well with the Jan 2006 and Feb 2007 results that show polarization 
parallel to the disk.  However, some of the individual dithers do agree 
well with these earlier data.  In particular the first and third do agree 
(in angle).  The second dither shows polarization perpendicular to the 
disk.  Lero is using tau correction and also background subtraction.

There were half-wave plate problems during this run and the previous run
(early April).  For these runs the iterating version of the EDAS code was
used.  So we should analyze these data using the -shn flag of
sharpinteg_2.  The issue is that for these files there were often more
than the usual number of half-wave plate positions (=4) due to the
iterative method used by the EDAS code to reach the desired position.  So
the analysis code can get confused by the extra iterations and can end up
deciding that there are more than four half-wave plate positions.  In this
case it may refuse to analyze the data or (even worse) possibly analyze it
incorrectly.  The -shn flag applied to sharpinteg_2 fixes this.

Lero has problems making ps files in IDL when using polsharp3, both on his
mac and on kilauea. The computer hangs and he does not get the IDL prompt
back.  John says sometimes he gets weird black splotches, and suggests
that if you can get an IDL prompt back, then device-comma-slash-close may
help.

Lero pointed out that no hwp value is posted for early April.  Giles
suggests using the value 90 until John has a chance to post one.  (Based
on the "table of V-nulls" posted in Fall 2007, this is almost certainly
close enough.)

- Hiroko will look into the postscript IDL problem on kilauea

- Giles will figure out what numerical value to use for -shn for Lero's
M82 analysis and also will determine precisely which runs need the -shn
flag

- Lero will plot up the hwp positions for all the cycles (files) from both
early and late April runs (M82 data only).  Giles will teach Lero how to
interpret these plots in order to classify the cycles as good or bad.

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Other items:

Giles has tested John's i.p. code and it seems to work!  John and Giles
will agree on some values for the i.p. parameters to be used for all 350
micron data collected since July 2006 and they will post these.

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The following items were not discussed on the telecon:

Mike's plans to make a smoothed tau for November 2007 

linked list-serves for SHARP (Giles action item)

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