Gamma-ray Large Area Space Telescope

1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope ISOC Peer Review 7.2 Science Operations Group Seth W. Digel HEPL, Stanford Univ.

2. Topics • Definition of the Science Operations Group (SOG) • Organization • Responsibilities • Implementation of the SOG • Current status • Transition from I&T • Timeline - synchronizing with the GRTs

3. Functional Organization of the ISOC • LOF – LAT operations and monitoring, and flight software and instrument testbed • SAS – Development, maintenance, and support of ground software, from instrument simulation to science analysis tools to the processing pipelines • SOG • Instrument calibration • Performance optimization • Operation of pipelines (data processing & transient source alerts) • Data distribution

4. Responsibilities – Instrument Calibration • See 7.1 for specifics about calibration of the LAT and ground operations for calibration • The SOG shall… • Maintain the data and the body of knowledge gained by I&T from the engineering models and the beam tests • N.B. I&T will transition to SOG, as has already been mentioned • Use flight data on an ongoing basis to maintain calibration of the LAT • E.g. (not exhaustive), Gain calibrations of ACD PMTs, pedestals and gains for PINs in CAL, dead/hot strips in TKR • N.B. In-flight Calibration relies on a Collaboration-wide effort and leadership from ISOC • In flight Calibration Tasks are identified in LAT-MD-00446 • TBRs have to do with whether data are reduced on-orbit and the frequency of recalibrations • The TBRs will be removed as we develop and test ISOC concepts and as hands-on experience is gained in I&T

5. Instrument Calibration (2) • Optimize the settings of the LAT in flight • This will be in response to in-flight changes in the hardware – e.g., silicon strips becoming ‘hot’ or dead • Generate LAT response functions • The response functions are the high-level characterizations of the performance of the LAT; these are central to the high-level data analysis • As needed, in response to change in LAT performance or update of reconstruction/classification of events

6. Responsibilities – Operation of Processing Pipelines • Whatever tasks that sensibly can be automated will be • A general purpose processing server is being developed by SAS (§ 4.3) • The SOG shall (using the pipeline processing system) … • Back-up all data products (cf §4.3) • Perform Level 1 processing • Unpacking L0 LAT science data • Assessment of science data quality & generation of diagnostics for the LOF • Reconstruction & classification of events • Search for transient sources & monitoring of selected sources • LAT team has the responsibility to monitor for blazar flares • By agreement with the project, fluxes for a short list of blazars will be made publicly available regularly and promptly during the sky survey (Phase 1)

7. Operation of Processing Pipelines (2) • Process LAT GRB transient alerts • When the associated event data will arrive is still TBD (might be able to have it travel with realtime telemetry during a contact) • Automatically monitor the calibration • E.g., fluxes of standard, steady sources • Generate Monte Carlo data sets of simulated LAT data • These will generally be major processing undertakings authorized by the LISC in support of studies of reconstruction, background rejection or response functions • Update to the response functions will be required after recon or classification are updated by SAS • Supporting reprocessing in any of these areas as required

8. Responsibilities – Data Distribution • The SOG shall… • Maintain the Level 1 database of processed events along with intermediate-level results (the ‘Level 0.5’ database) • Maintain the the other high-level databases needed by the standard analysis environment • Ref. Standard Analysis Environment design report (http://www-glast.slac.stanford.edu/sciencetools/reviews/sept02/) • Pointing/livetime/mode history, response functions • Distribute data according to established ICDs to the GSSC, to LAT mirror analysis sites, and directly to LAT collaborators

9. Interfaces to SOG • SOG-centric view of data flow to and from the SOG, i.e., the interfaces with the LOF, SAS, the LAT Collab. and the GSSC LAT Science Data, alert messages SOG SAS Instrument simulation Science tools Pipeline server LOF High-level diagnostics Config. of LAT LAT HK ISOC Data products Response functions Instrument simulation Science tools Support for LAT collab. GSSC LAT Collab.

10. Implementation of the SOG • Some of the functions of the SOG are distributed across the collaboration • In particular, expertise with the calibrations of the LAT subsystems lies with the developers of the subsystems • Core functions of the SOG will be coordinated by a dedicated group at SU/SLAC • In particular, pipeline operations (data processing, transient alerts) and data distribution • The SOG activities at SU/SLAC will be co-located with the LOF

11. Implementation (2) • Overall oversight of the SOG will be by the LAT Instrument Steering Committee (LISC) • The LISC will represent the science interests of the LAT collaboration • It will also have oversight over reprocessing, including decisions about when reprocessing data in response to changes of instrument performance or event reconstruction

12. Summary • The SOG serves science needs of the collaboration, in terms of pipeline processing, instrument optimization, and calibration • It also distributes processed data to the GSSC • The interfaces internal and external to the ISOC are understood and detailed requirements are being developed • The transition from I&T to SOG is being developed as well.