Science Tools Working Group

We met last week; most likely we will not meet again until August 9.

The current version of the Science Tools remains v7r3, although an increment in honor of the end of the build cycle tomorrow is in the works.

Data products: The proposed changes (cleaning up) of the FITS header for FT1 (LS-002) have been implemented in makeFT1 by Jim; among other changes this involved making makeFT1 run as an FTOOL, which gave it access to information about its own package version number, which gets written to the CREATOR keyword. I think that this is now the definition of LS-002 that we'll be going with for GRT 5.

Databases and related utilities

No news regarding the GSSC server. It has been inaccessible recently, most likely owing to the general server outage.

Jean-Paul visited SLAC last week for the conference on Web engineering and had time to meet to discuss the Astro Data Server. Jean-Paul is confident that the MySQL implementation that underlies the Astro Data Server can handle (ingest and serve) much larger data sets than DC2's, and some possibilities like generating output FITS files in parallel on a few systems have not been explored. We'll certainly extensively exercise the Astro Data Server in the coming months. Most likely Tony will implement the command-line interface to the server; after discussion with Jim and Richard this week, I see this has some interesting aspects (depending what you like) regarding whether the queries are synchronous and how they can be managed within Pipeline 2. The persistent problem with the GTIs required reingesting the DC2 FT1 files is 99.8% solved - meaning that 520 out of 521 time intervals are now returned for DC2 queries. The missing interval is the first and its absence is being looked into.

Likelihood analysis

From Jim: "I fixed a bug that occurred when trying to analyze data with zero events; and I rewrote the Amoeba class, which is used by gtfindsrc to point source position fitting, to get around a linking problem on Windows."

GRB tools

James sent this following clarification and update about the issue with Xspec analysis of GRBs that was reported last week. I have not followed up yet with questions about the response functions.

James and Dave Davis continued exploring in detail the behavior of rspgen. As a basic sanity check, Dave simulated an extremely bright power law source (to boost the number of counts) observed in a pointed observation. With the response matrix computed by rspgen, the spectum of this observation was analyzed in Xspec. When using the full range of energy selected, Xspec consistently got the wrong answer (too low) for the exponent in the power law of the source. Further experimentation revealed that the fit converges to the correct answer if one uses only the central energy range of the spectrum.

One problem they uncovered and subsequently solved was that the combined dispersion for DC2 (which includes 4 individual responses, FRONTA/BACKA/FRONTB/BACKB) was not being renormalized to 1 by rspgen. When this was fixed the behavior of rspgen improved somewhat, in that Xspec's answer was closer to the right answer, but still not statistically correct. However, at higher true energies, slices of the dispersion matrix coming from the irfs packages do not seem to be normalized to 1 to begin with, resulting in some artifacts.

To probe further, James and Dave examined the separate components of the DC2 response. They found that the effective area and dispersion seem believable, but the psf has a very odd shape, particularly for
the front events. It's still unclear what about the data set and/or the response matrix is causing Xspec to fail to converge to the right answer.

Pulsar tools

From Masa: "We are in the final stage of implementation of time handling classes in the pulsar tools."

Observation simulation

From Jim: "I modified primary HDU header keywords in the the FT1/2 FITS template files to conform to HEASARC conventions and according to our consensus decisions as to what they should be, and I modified makeFT1, gtobssim and gtorbsim to fill the FILENAME, VERSION, and CREATOR keyword with the proper values."

User interface and infrastructure

No news

Source Catalog

The catalog group met yesterday. Jean presented a comparison of the DC2 catalog with the DC2 sources that were detectable; the results are reassuring in most respects but a bit curious in others. We discussed 'test pattern' source distributions for testing source detection algorithms and a 0-th iteration of the agenda for the Catalog session at the collaboration meeting.

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