Summary of Aug. 29 chop-nod analysis telecon (Mike, Hiroko, Giles)

We discussed three tasks that John and Darren have been doing but that 
we need to get the larger group involved in.  These need to be done 
after each run in order to provide data to be used during SHARP chop-nod 
analysis:

1. pointing model:  This involves using FAZO and FZAO determined "after 
the fact" to create a model for how FAZO and FZAO changed during the 
run, as a function of time, AZ, and EL.  (These "revised pointing 
corrections" are then used as an input to sharp-combine.)

2. rgm:  Determine the relative gains of the 288 pixels that are used by 
SHARP.  May change from run to run.  (May even change within a run but 
we have no sophisticated solution to this.)  These gains are then stored 
in an "rgm file".  This task involves some understanding of sharcsolve.

3. smoothed tau:  Fit the recorded tau values so as to produce a data 
set of tau vs. time with less noise it in.  These are fed into 
sharp-combine along with the new pointing offsets.  I think this task 
seems at this point to be relatively easy, as a recipe has been developed.

Except for the pointing model task, I think we are up to date on these 
tasks, through the August run.  Hiroko noted that by using fitgauss on 
sharpinteg output, the pointing corrections for reasonably bright and 
compact sources can be carried out without the need for a "pointing 
model".  It seems likely that this will work fine for such sources, and 
is a good way to make progress in the absence of a pointing model.

We also discussed another task that seems to be needed, based on my 
mountain-top examination of IRAS20126 results.  We need to develop a way 
to compute the reduced-chi-squared for a data set.  This will be used to 
assess reliability and probably also to inflate error bars.

Hiroko and Darren are working on the rgm task.

Mike and I have been thinking about the reduced-chi-squared task.  As a 
start, Mike has been performing an analysis of the Feb. 2007 M82 data 
that follows closely along the lines of what I posted for DG Tau.  He 
has made a first pass through about half of this work (parts I, II, and 
III of the DG Tau memo), and we discussed some of the details in section 
III which deals with comparing the noise in the sharpinteg maps to what 
is expected from the signal-to-noise predictions on our SHARP web page.