Core Minutes 6/13/2006  

Present:    Joanne Bogart, Anders Borgland, Toby Burnett, Jim Chiang, Richard Dubois, Dan Flath, Navid Golpayegani, David Landriu, Michael Kuss, Bryson Lee, Francesco Longo, Chuck Patterson Igor Pavlin, Leon Rochester, Tracy Usher

• Beamtest: (Richard) It now appears it will start on time and we will get the originally-promised amount of running time. Work is ongoing on the following:
  • Matrix of simulations: SPS and PS, different energies, different positions and orientations. We're just about ready to start these runs. (Francesco) We may need to rerun some old tasks as well to take account of added material.
  • Visualization: Francesco has provided a Linux version of Geant visualization libraries for Geant4, V8. Riccardo has been contacted to do the same for Windows so that these libraries can be part of GlastRelease as well. [Hurrah! ed.]
  • Ancillary components calibration: (Joanne) has received a description of tagger calibration information and has a draft XML format which will serve. She would like at least a rough description of proposed calibrations for the other ancillary detectors before proceeding further, in order to provide as streamlined a design as possible, minimizing duplication of effort.
  • Reconstruction of ancillary data: (Leon) Nicola produced a first version which reads a separate data stream into Gleam, manipulates the data and writes results to a tuple. Recommendation from an informal code review was to break up the code into separate packages and save intermediate results as is done for other data. Nicola has started on the redesign, but will be attending the Elba conference next week. Heather and Leon will finish remaining work, if any.
  • Pipeline tasks: Warren has agreed to take this on. He returns from NRL on Monday. [addendum: he's working on it now from NRL and may be nearly done already]
• Processing: (Richard) Tom is about done with background events; we have our 5 billion. Next he'll produce 18 million allgammas. There was an anomaly last time when reprocessing: Richard thinks it had to do with MC Z-dir, which had a narrower distribution the second time around. (Toby) has been looking for a recurrence of this problem and hasn't seen it. However, there were other problems. One, still to be resolved, concerns EbfWriter, which requires glt information but does not check for its presence. Conceivably some revision of job options would help, but in any case EbfWriter should protect itself. (Richard) The job options used for Pipeline jobs probably should be added to Gleam.

  After his tour through various people's code, Toby also requests that everyone follow recommended procedures by putting a CVS header line

  //  $Header:   $
  

  near the top of each code file. When the file is checked in, CVS replaces this line with version information.

  The question of using the allgammas for examining extragalactic diffuse emissions was raised. Thanks to Jim for this explanation:

  During the Calibration & Analysis meeting Toby proposed that we could use the AllGamma runs to determine what the extragalactic (EG) diffuse emission should look like on orbit, since both sources, the AllGammas and EG diffuse, are distributed isotropically on the sky, the former in instrument coordinates and the latter in Celestial. Julie [actually Bill; see below] objected that the AllGamma runs could not be used since they do not account for SAA passages. The point I made today is that the livetime cubes do account for SAA passages during the course of an observation period, and so they keep a record of the amount of time any point on the sky spends within a given inclination range with respect to the instrument z-axis. So by summing up those distributions of off-axis integration times, one could directly scale the AllGamma data to get an estimate of what the EG diffuse counts spectra should look like without having to run a separate Gleam simulation.

  and to Julie for more information about what occurred at the C & A meeting:

  In the discussion about AllGamma vs ExDiff at the C&A meeting, I didn't argue that we needed to account for SAA passages (that was Bill).

  I said that I had made a sample of Exdiff because I wanted the entire unocculted sky (not just the bit above the LAT horizon), it turned out that this did not matter, but I wanted to convince myself. Bill wants to be able to do things like apply zenith cuts to the Exdiff, just as we do to the background. He is also thinking about orbit position dependent cuts. Both of these could in principle be done by weighting AllGamma correctly, but it is at the moment awkward.

  I completely agree that AllGamma should be sufficient, and that we should be able to correctly account for exposure due to SAA passages, zenith cuts, orbit dependent cuts (or we would have difficulties evaluating exposure for point sources). However, at the moment we are not yet set up to do this so it makes sense to generate the diffuse source.

• Quick Look: (Jim) The project has a new name and a new acronym: Automated Science Processing. The idea is to look for some kinds of science on the fly, or nearly, as data come in. Several of the items concern GRB's:
  • Refine positions
  • Blind search
  • Look for afterglow emissions

  We will also look for flaring sources (not easy: it will mean pixellating the sky and keeping a history of flux by pixel to look for variations) and will monitor a predefined set of sources.

  (Richard) This project also requires some underpinnings, such as a scheme for making results available on the Web.

• ISOC meeting: (Richard) The new series of ISOC meetings can be viewed as a follow-on to the monthly LAT commissioning meetings we used to have. The first ISOC meeting tomorrow will probably largely be used just to explain who is doing what.

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J. Bogart, Last Modified: 01-Jun-2010 15:46:38 -0700