GLAST Large Area Telescope: Science Analysis Systems and Collaboration Computing Needs Robert Cameron, Richard Dubois St

1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope: Science Analysis Systems and Collaboration Computing Needs Robert Cameron, Richard Dubois Stanford Linear Accelerator Center

2. Outline • SAS Overview • Service Challenge update • Support for LAT Collaboration Science Groups • Support for ISOC Operations Testing • Computing Resource Projections

3. 1 Gev Gamma Incident Gamma e+ e- Note energy flow in direction of incident Gamma Radiated Gammas ~8.5 Radiation Lengths SAS: Fusion of HEP & Astro “Science Tools” • Collection of tools for detection and characterization of gamma-ray sources (point sources and extended sources) • source finding • max likelihood fitting (binned/unbinned) • parameterized instrument response • exposure maps • comparisons to model (observation sim) • periodicity searches, light curves • Science Tools are FITS/FTOOLS based • for dissemination to astro community Event Interpretation + full code development environment on linux, windows (mac imminent), code and data distribution, automated code builds, documentation etc etc Full simulation/reconstruction of 1 GeV gamma

4. Data Challenges • A progression of data challenges. • DC1 in 2004. 1 simulated week all-sky survey simulation. • find the sources, including GRBs • a few physics surprises • DC2 in 2006, completed in June. • 55 simulated days (1 orbit precession period) of all-sky survey. • First generation of LAT source catalogue • Added source variability (AGN flares, pulsars). lightcurves and spectral studies. correlations with other wavelengths. add GBM. study detection algorithms. benchmark data processing/volumes/reliability. • 200k batch jobs - worked out reliability issues (< 0.1% failure rate now) Data challenges provided excellent testbeds for science analysis software. Full observation, instrument, and data processing simulation. Team uses data and tools to find the science. “Truth” revealed at the end.

5. Post DC: Service Challenge • Coordinate simulation studies • will need a common set of simulations plus a near-constant stream of simulations to support special studies. Develop capabilities outside SLAC as needed using collaboration resources. • Operations readiness testing coordinated with the mission-level End-To-End tests. • leverage off the ETE tests for internal-to-LAT readiness • a sequence of “service challenges” for readiness testing serves these needs better than what is needed for systematic studies by science topic. • Organize by area • Science groups, led by LAT Analysis Coordinator • ISOC, led by ISOC managers

6. Systematic & Sensitivity Studies pt sources, extended sources, transients; upper limits diffuse analyses variability (incl. pulsars) neighboring sources flaring & diffuse effects focus on 1st papers analyses Operations Readiness Tests digital data problems instrument problems (bad channels, wrong rates, recognizing a few wrong constants, …) Automated science processing receiving data dumps, running the pipeline, benchmarking resources and times, reliability idiosyncrasies vs. problems day(s) in the life performance monitoring documentation SC Work to be Done: Responsibilities ISOC Analysis Coordinator and Science groups Other Studies • PSR (“handoff review”) performance • analysis tuning (signal/bkgd, quality knobs by topic) • update simulation (s/c model, tune from beam test and IA data…) • first light observations (simulate point, then scan); early ops analyses • effects of burst repoints • sky survey strategy checks • background fluxes evaluation early ops C&A group and ISOC jointly Collaboration participation needed

7. SC: Connection to Science Groups • Several datasets have been identified for the Science Groups use: • 1 year survey simulation, using obssim science tool (completed) • Fast Monte-Carlo with parameterized responses and efficiencies • Early testing of sky model; opportunity for Science Groups to exercise analyses on realistic sky with long observations • 55 day simulation using GLEAM (LAT event simulator) (imminent!) • Full simulation • Earth occultation not currently in exposure calculations • Autonomous Repoint Requests • LAT/SC misalignment • Background interleave for pointed observations • 1 year GLEAM simulation • Final pre-launch science performance • Potentially huge backgrounds run needed • Targeting use of Lyon, Italian computer farms • Plus a few smaller scale specialty runs as needed • Plan on delivering obssim and 55 day runs for the end-July LAT collaboration meeting; 1 yr Gleam run in August. • Milestone for next versions of Data Catalogue, LAT Data Servers

8. SC: Operations Testing for the ISOC • Strategy defined from ISOC Science Operations and Service Challenge workshop • Use ETE tests for control room type functions • Shift log, Level1 pipeline, Data Catalogue, Monitoring • SAS products • Use simulations to prep for ETE & provide realistic science data, extended running • Simulate Level0 science data • Prep for ETE Level1 pipeline usage • Realistic science data for response distributions, resource usage, latencies etc • Downlink simulations for instrument readiness tests, such as calibrations, failed sensors etc. • Demonstrated, but need background interleave scheme for big datasets • 55 day, 1 year orbit runs • Extended run to test Automated Science Processing • Time trending of instrument quantities

9. Simplified Diagram for ISOC Data Flow - testable with simulations Ingest L0 data S FastCopy MOC S S L0 Archive S Create data analysis ntuples Data Receiving Calibrations and L1 processing S Create recon files and perform event classification Merge Events Extract Context Extract EBF Create digi files S S Automated Science Processing S Analyze charge injection data (LCI) Get Calibration from DB Analyze calibration data (LPA) S S Output Data Products to LAT Collaboration and GSSC MOOD/MOOT (config DB)

10. Data Access: LAT Data Portal • Provide collaboration access to both summary “photon” data and full digi/recon/(MC) data • Provide data in both FITS and Root format • Main components • Astro Data Server • select events based on position in the sky, energy, time, or event class • Data Skimmer • Select events based on “TCut” able to access full merit tuple (400+ columns) • Access full data for list of runs/events • Event Display (WIRED) • View detailed detector response for list of runs/events • Data Catalogue is underpinning with all the dataset bookkeeping • File locations • Flexible user definable meta data http://glast-ground.slac.stanford.edu/DataServer/dc2/ Under revision for the 55 day run

11. Current Computing Resources at SLAC Starting 3rd year of projected annual $300k Capital Equipment Projects • Supplying batch farm disk & CPU, as well as dedicated servers • Optimize purchases based on best deals SCCS can come up with • 150 TB disk (45 TB still available) • LAT Commissioning • DC2/SC • LAT Beamtest • Infrastructure needs (code builds; system tests; user disk) • Tremendous use of SLAC Batch farm • 160 cores (40 dual core, dual CPU boxes) owned by GLAST • Leveraged to > 300 cores during extended simulations runs • Will have 400 cores at SLAC • Not looking good for quad core CPUs to be available this year

12. Known Liens on Resources • GLAST/LAT Data taking at General Dynamics • EMI/EMC testing is underway for 30 days • Thermal-vacuum testing in late summer, ~40 days • 55 Day run • One week processing time; 5 TB disk • Service Challenge 1-year run in August • 40 days running @ 300+ cores • ~30 TB disk (Note: disk space needs are reduced compared to on-orbit data taking due to use of background interleave scheme) • ETEs • Small data volumes on this scale • Launch • Estimate ~100 cores needed to process a 3-hour downlinked dataset in about an hour • 400 cores will provide a pool of cores for prompt processing & monitoring; reprocessing; and simulations • Will order 150 TB disk to be on hand at launch

13. Computing: Planned Acquisitions • SLAC • Order for 50 TB disk and 240 cores in process • ship date is end June (from Sun); to be installed mid July • Additional 150 TB to be acquired for launch readiness • Funds from SLAC & LAT Operations Collaboration Fund • Univ of Washington (in use now) • ~100 physics dept lab CPUs on cycle-available basis (when students are not using them) • Used for CPU intensive simulations • Lyon • IN2P3 is providing 100 CPUs, 50 TB disk • porting LAT processing pipeline infrastructure (Pipeline2) to Lyon now • CNAF • INFN has submitted proposal for 100 CPUs, 25 TB (in 07) • Approved • Will be required to access via GRID tools

14. What to Take Away • Service Challenge + End-To-End tests • Being used to hone the tools, complete development and test end-to-end operations • Computing resources: prudent approach is being implemented • Acquire ~400 cores at SLAC available for GLAST • Lesson learned from 5-ring circus of DC2, LAT Beam Test, I&T • Keep full event details on disk in ‘08 : ~175 TB • GLAST will do better science the more compute power it has access to • Have not hit the plateau yet! • Extending LAT processing pipeline to France and Italy