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(Julie McEnery Nov 27)-- It would be handy to have a way to calculate an upper limit. I think that this will eventually be needed. (Jim 11/29/06: Computing an upper limit will, of course, require first understanding the null distribution, i.e., the TS distributions that David refers to above.)
Jim Chiang (11/29/06)--It has been proposed by Jean Ballet to compute a hybrid likelihood that combines an unbinned analysis for higher energy events that have better PSFs and are sparser, and a binned analyis for lower energies, where the PSF is not as good and binning would help speed up the execution without significant loss of accuracy. Alternatively, we could (also) implement a HEALPix binning scheme, based on Toby's work, that would provide similar computational savings.
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DLB (11/26/06)--The lightcurve functionality in gtbin just bins the counts in an FT1 file in time. The lightcurve therefore does not compensate for the exposure. For those of us who look at gamma-ray burst lightcurves this is OK; indeed to plan further analysis this is what we want. However, those looking at sources on longer timescales (i.e., over orbits) may want to correct for exposure; AGN people have requested this. For the counts from a point source this makes sense, but this can be problematic when the counts originate from a large region. So...should we create/add exposure correction?
Jim Chiang (11/29/06)--For my DC2 analysis of the Solar flare, I wrote an exposure tool that does such an exposure correction as a function of time at a specific location on the sky. For the Solar flare, I made a comparison of the light curve obtained using gtbin and the output of this exposure tool versus the flux estimates from a full likelihood fit of the fluxes. At least for bright sources such as the DC2 Solar flare, the comparison was quite favorable. See my DC2 close-out talk. I will make this exposure tool into a proper ScienceTool.
DLB(11/26/06)--gtbin was meant to be a simple binning tool, i.e., accumulating counts into energy/temporal/spatial bins. It does not calculate uncertainties for the number of counts. However, showing uncertainties would be appropriate in displaying the products, particularly when the counts are divided by livetime or exposure, or undergo some other transformation. So, how should we proceed?
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