GLAST The Gammaray Large Area Space Telescope The

GLAST The Gamma-ray Large Area Space Telescope The GLAST Mission AGILE-GLAST Workshop Guido Barbiellini University and INFN Trieste GLAST SSAC for the GLAST LAT collaboration GLAST Mission – G. Barbiellini

Outline • Context • From SRD to real instrument • Instruments (LAT & GBM) – Capabilities, status • Operations and data • Summary GLAST Mission – G. Barbiellini

GLAST Key Features • Next-generation high energy gamma-ray observatory – Huge field of view, optimized for sky survey • Full sky every 3 hours. – Huge energy range, including largely unexplored 10 Ge. V - 100 Ge. V band – Unprecedented sensitivity – Will transform the HE gamma-ray catalog: • By > order of magnitude in number of point sources • Sub-arcmin localizations (source-dependent) • Map spatially extended sources Large Area Telescope (LAT) PI: P. Michelson (Stanford University) 20 Me. V – >300 Ge. V GLAST Burst Monitor (GBM) PI: C. Meegan (NASA/MSFC) Co-PI: G. Lichti (MPE) 10 ke. V – 30 Me. V Launch: January 2008 5 year mission life (10 year goal) GLAST Mission – G. Barbiellini GLAST Burst Monitor (GBM)

The EGRET legacy The Compton Gamma Ray Observatory (CGRO) is a sophisticated satellite observatory dedicated to observing the high-energy Universe. It is the second in NASA's program of orbiting "Great Observatories", following the Hubble Space Telescope. While Hubble's instruments operate at visible and ultraviolet wavelengths, Compton carries a collection of four instruments which together can detect an unprecedented broad range of high-energy radiation called gamma rays. These instruments are the Burst And Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). GLAST Mission – G. Barbiellini

The EGRET legacy GLAST Mission – G. Barbiellini

The EGRET legacy Kouveliotou et al 1994 Sommer et al. 1994 GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements • provides spectra for bursts from 10 ke. V to 30 Me. V, connecting frontier LAT high-energy measurements with more familiar energy domain; Simulated GBM and LAT response to timeintegrated flux from bright GRB 940217 Spectral model parameters from CGRO wide-band fit 1 Na. I (14 º) and 1 BGO (30 º) • provides wide sky coverage (8 sr) -- enables autonomous repoint requests for exceptionally bright bursts that occur outside LAT FOV for high-energy afterglow studies (an important question from EGRET); • provides burst alerts to the ground. GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

GLAST requirements GLAST Mission – G. Barbiellini

Scientific Requirements Document GLAST Mission – G. Barbiellini

HE Gamma Ray Telescope • Pair production telescope for high energy gamma rays – Tracker, calorimeter, and anti-coincidence shield work together to measure direction and energy of -rays and reject background – Optimization • Angular resolution: many thin layers of fine-pitch TKR • Energy resolution: thick-as-possible CAL, segmented to measure shower profile • Rejection: efficient ACD particle detection, segmented to minimize self-veto from -ray shower backsplash The Anti Coincidence Detector vetoes incoming charged particles The reconstructed vertex points back to the source Track of a charged particle, measured by position sensitive detectors e+ GLAST Mission – G. Barbiellini e– The Calorimeter measures the photon energy Conversion foil: the photon interacts to produce an e e+ pair

GLAST LAT Collaboration • • • United States – University of California at Santa Cruz - Santa Cruz Institute of Particle Physics – Goddard Space Flight Center – Laboratory for High Energy Astrophysics – Naval Research Laboratory – Ohio State University – Sonoma State University – Stanford University (SLAC and HEPL/Physics) – University of Washington – Washington University, St. Louis PI: Peter Michelson (Stanford & SLAC) France ~230 Members (including ~184 Affiliated Scientists, – IN 2 P 3, CEA/Saclay plus 24 Postdocs, and 36 Graduate Students) Italy Cooperation between NASA and DOE, with key – INFN, ASI, INAF international contributions from France, Italy, Japan and Sweden. Japanese GLAST Collaboration – Hiroshima University Managed at Stanford Linear Accelerator Center (SLAC). – ISAS, RIKEN Swedish GLAST Collaboration – Royal Institute of Technology (KTH) – Stockholm University GLAST Mission – G. Barbiellini

Large Area Telescope (LAT) Overview • Precision Si-strip Tracker (TKR) – 18 XY tracking planes. Single-sided silicon strip detectors (228 mm pitch), 880, 000 channels. – Tungsten foil converters • 1. 5 radiation lengths – Measures the photon direction; gamma ID. • Hodoscopic Cs. I Calorimeter(CAL) – Array of 1536 Cs. I(Tl) crystals in 8 layers. 3072 spectroscopy chans. • 8. 5 radiation lengths – Hodoscopic array supports bkg rejection and shower leakage correction – Measures the photon energy; images the shower. • Segmented Anticoincidence Detector (ACD) – 89 plastic scintillator tiles. – Rejects background of charged cosmic rays; segmentation minimizes self-veto effects at high energy. • Electronics System – Includes flexible, robust hardware trigger and software filters. ACD [surrounds 4 x 4 array of TKR towers] e+ Tracker e– Calorimeter Systems work together to identify and measure the flux of cosmic gamma rays with energy 20 Me. V - >300 Ge. V. GLAST Mission – G. Barbiellini

LAT Instrument Performance • Performance significantly improved over EGRET – Improved angular resolution, effective area, and FOV – Point-source sensitivity ~ 4 × 10 -9 ph cm-2 s-1 • Factor of 25 better than EGRET – Expect source catalog to contain several thousand objects LAT EGRET 20 Me. V – >300 Ge. V 20 Me. V – 30 Ge. V <10% 9000 cm 2 1500 cm 2 Angular resolution (single photon, 10 Ge. V) 0. 15 0. 54 Field of view 2. 2 sr 0. 5 sr Deadtime per event 27 us 100 ms Energy range Energy resolution (on axis, 100 Me. V – 10 Ge. V) Peak effective area GLAST Mission – G. Barbiellini

2 Bismuth Germanate (BGO) Scintillation Detectors Overview of GBM 12 Sodium Iodide (Na. I) Scintillation Detectors Major Purpose – – Provide high-energy spectral coverage (150 ke. V – 25 Me. V) to overlap LAT range over a wide Fo. V 5” diameter x 0. 5” thickness • • – – – Provide low-energy spectral coverage in the typical GRB energy regime over a wide Fo. V (10 ke. V – 1 Me. V) Provide rough burst locations over a wide Fo. V 5” diameter x 0. 5” thickness Provides spectra for GRB from 10 ke. V to 30 Me. V GBM provides on-board GRB locations over the entire unocculted sky. The observatory can be re-oriented to obtain LAT observations of afterglow from strong bursts. GLAST Mission – G. Barbiellini

GBM Collaboration National Space Science & Technology Center University of Alabama in Huntsville NASA Marshall Space Flight Center Charles Meegan (PI) On-board processing, flight software, systems engineering, analysis software, and management GLAST Mission – G. Barbiellini Max-Planck-Institut für extraterrestrische Physik Giselher Lichti (Co-PI) Detectors, power supplies, calibration, and analysis software

GBM System Performance • • GBM data types – Time-tagged event data during bursts – Two types of histograms, continuously • One optimized for spectroscopy (8 -sec avg, 128 chans) • One optimized for timing (0. 25 -sec avg, 8 chans) Burst summary – On-ground location accuracy: < ~ few degrees – Expected GBM burst-detection rate • ~70 bursts per year in FOV of LAT • ~220 bursts per year total Parameter Expected or Measured Performance Energy range ~8 ke. V – 30 Me. V (measured) Energy resolution 15% FWHM at 0. 1 Me. V (measured) 8% FWHM at 1. 0 Me. V (measured) On-board GRB locations <15 for any pointing <8 for S/C zenith angle < 60 GRB sensitivity (5 s, on ground) 0. 47 ph cm-2 s-1 (peak flux, 1 s, 50 -300 ke. V) GRB on-board trigger sensitivity 0. 71 ph cm-2 s-1 (peak flux, 1 s, 50 -300 ke. V) Field of view 9. 0 sr GLAST Mission – G. Barbiellini ~ 1/3 BATSE sensitivity

GBM Hardware Full complement of GBM flight hardware 12 Na. I detectors, 2 BGO detectors, Power Supply Box, and Data Processing Unit integrated for functional testing at the National Space Science and Technology Center (NSSTC) in Huntsville, AL GLAST Mission – G. Barbiellini

GLAST Burst Monitor on Spacecraft GLAST Mission – G. Barbiellini

GLAST Mission – G. Barbiellini

GLAST MISSION ELEMENTS msec • • GPS Large Area Telescope & GBM DELTA 7920 H - • Telemetry 1 kbps • GLAST Spacecraft TDRSS SN S & Ku • • S - • GN • Schedules Mission Operations Center (MOC) GRB Coordinates Network GLAST Science Support Center Schedules Alerts Data, Command Loads GLAST Mission – G. Barbiellini LAT Instrument Science Operations Center White Sands HEASARC GSFC GBM Instrument Operations Center

Operations Phases, Guest Observers, Data • After the initial on-orbit checkout, verification, and calibrations, the first year of science operations will be an all-sky survey. – every region of the sky viewed for ~30 minutes every 3 hours – first year data used for detailed instrument characterization, refinement of the alignment, and key projects (source catalog, diffuse background models, etc. ) needed by the community – data on transients and “sources of interest” will be released, with caveats – repoints for bright bursts and burst alerts enabled – extraordinary To. O’s supported – workshops for guest observers on science tools and mission characteristics for proposal preparation • Observing plan in subsequent years driven by guest observer proposal selections by peer review (default is sky survey mode). Public data released through the science support center (GSSC). GLAST Mission – G. Barbiellini

GLAST Science Support Center (GSSC) • • Supports guest observer program, provides training workshops, provides data and software to community, archives to HEASARC, joint software development with Instrument Teams, Teams utilizing HEA standards. Located at Goddard. GSSC tasks: – Data Archive • The server for LAT photons and events is ready and in use for DC 2 and SC 2. – Operations • Scheduling tool. • Software to support To. Os and to process observing timelines – User Support • Timelines, exposure and count maps, and various reports will be posted on the GSSC website. • The GSSC is actively involved in the Science Analysis Environment (SAE), the definition of the data products, and the writing of documentation and workbooks. see http: //glast. gsfc. nasa. gov/ssc/ GLAST Mission – G. Barbiellini

MW Info and Coordination • Multiwavelength observations are key to many science topics for GLAST. – GLAST welcomes collaborative efforts from observers at all wavelengths • For campaigners’ information and coordination, see http: //glast. gsfc. nasa. gov/science/multi • To be added to the Gamma Ray Multiwavelength Information mailing list, contact Dave Thompson, djt@egret. gsfc. nasa. gov • GI Program supports correlative observations and analysis – See http: //glast. gsfc. nasa. gov/ssc/proposals GLAST Mission – G. Barbiellini

Conclusions • EGRET survey >100 Me. V, full mission GLAST Mission – G. Barbiellini Simulated LAT sky survey – One year exposure – >100 Me. V image