Summary of dicussion during chop-nod analysis telecon of Nov. 21, 07 Martin, Hiroko, Mike, John, Giles _________________________________________________________________ M82 data from February 2007: We decided to defer work on this for a bit, until we see what we have for IRAS 20126 and NGC 1333 IRAS 4A. The latter source, in particular, provides a good data set for Mike to test his planned new reduced-chi-squared procedures. Note that one of the late-October posted chop-nod-analysis telecon summaries has a list of improvements that could be done to improve Mike's posted M82 analysis. ___________________________________________________________________ IRAS 20126 data from August 2007: Hiroko has a new result that looks pretty similar to the mountaintop analysis. She E-mailed it to the chop-nod group. She has incorporated pointing corrections and smoothed tau corrections. She used "50 50" for the background subtraction parameters. Note that the first parameter is the number of iterations of background subtraction while the second parameter is the number of iterations of gain correction. We really should be using "50 0" not "50 50" since the gain correction is most useful for brighter sources and is not well tested. Even the background correction w/o gain correction is not terribly well tested. John recommends that Hiroko should study this to make sure that it is working well and he will help her on this. We decided Hiroko's next steps should be to repeat the analysis with some changes, and write up a memo describing the results. The changes are: use "50 0" not "50 50" as background-subtraction parameters with John's help, make sure the background-subtraction is working If possible, do some simple tests to make sure that the pointing corrections and smooth tau are working. For example: a) Does the FWHM of the I-map go down when the pointing corrections are applied, as expected if the pointing corrections are valid? b) Does the corrected peak brightness of the individual sharpinteg maps (as determined by fitgauss) become more constant when the smoothed-tau is used? Note that the corrected peak brightness is found by multiplying the raw intensities by exp(25*tau*airmass). If possible, apply i.p. correction. Giles will test the i.p. correction software next week, and then teach Hiroko how to use it. Break data into a number of equal-weight bins, so we can do an "intuitive" reduced-chi-square. _______________________________________________________________________ NGC 1333 IRAS 4A data from November 2007: Mike showed a map which has a few 3-sigma vectors over a 12" diameter region centered on the peak. Next steps are: background subtraction (but no gain correction, see above) smoothed tau...Mike will create with help from John pointing corrections...Mike will verify that the parameter "delta" in fitgauss3 sets a sliding mask so that data from the other peak can be excluded when fitting. Then he can set it appropriately and recompile if necessary. i.p. ... Mike and Giles to work on this next week develop reduced-chi-square procedures _______________________________________________________________________ Giles learned how to use polsharp3 and make simple mods: OK, this was after the telecon had ended, but John stayed on and showed Giles how to edit the IDL procedures so as to suppress polarization vectors from being plotted where the flux is very low, and how to shift around the positions the vectors, for the case where one is skipping vectors. I made a new file sharp_plotG1.pro that replaces sharp_plot3.pro and I verified that I can do these simple mods and recompile in IDL. Note that anyone who does this kind of fooling around with the IDL routines should of course be very careful and should probably consult me or John first. This kind of stuff is definitely "unsupported". _____________________________________________________________ The following item was not discussed on the telecon: linked list-serves for SHARP _____________________________________________________________