Science Tools Working Group

We did not meet this week but most likely will meet on June 28.

The current version of the Science Tools remains v7r3

Databases and related utilities

No news.

Likelihood analysis

From Jim: "I fixed a couple bugs in the FileFunction model that allows one to use an ascii file with columns of energy and differential photon flux as the spectral model for a source."

"I have also determined that the biases that are affecting Likelihood fits to data generated using the DC2 IRFs arise almost entirely from the fact that the DC2 energy dispersion functions are not centered on or symmetric about the true energy of the photon and tend to result in systematically lower measured energies on average." (See slide 7 of my DC2 Kickoff talk on IRFs.) This effect should have been obvious in retrospect. I am working on a remedy for this."

Routinely in likelihood analysis we ignore the energy dispersion, because the response functions do not depend very strongly on energy at the level of the energy resolution. However, because the energy dispersion has an asymmetric distribution, Jim has realized that we are effectively introducing a systematic bias to lower energies in selecting the response functions to use in evaluating the likelihood function.

GRB tools

No news.

Pulsar tools

Masa and James worked on (or 'refactored') the TimeRep class that will implement the conversions between representations of time - like MET, MJD, etc., with a goal of having the class complete and in use by gtpulsardb, gtephcomp, gtpsearch, gtpphase, and gtophase by the end of the current build (July 21).

Observation simulation

No news

User interface and infrastructure

James and Analia have implemented some changes to st_graph to support plotting from gtlikelihood . James is continuing to work on ape, mainly bug fixes, for public release as part of HEAdas. Integration with the science tools will follow.

Source Catalog

The catalog group met this week, if you are interested. Jean presented initial results from evaulating significances for the 'true' sources in DC2 and the effects of removing the background from the data set. Also, he gave a detailed presentation of an updated estimate of the number of CPU days required for a catalog analysis for the current pipeline. Follow the link above.

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