G4 validation

1
GLAST Data Analysis Brief Introduction F.Longo,
N. Omodei, D. Bastieri Thanks to many LAT
collaborators For official info
http//www-glast.slac.stanford.edu
2
Outline

• Reconstruction and Analysis in GLAST LAT
• Science Software
• Tutorial on GRB SW

Real GLAST event
Simulated GLAST event
3
Event Trigger and Recon
4
LAT GeometrySimulation and Reconstruction
5
Instrument Triggering and Onboard Data Flow
Hardware Trigger
On-board Processing
Onboard filters reduce data to fit within
downlink, provide samples for systematic studies.
Hardware trigger based on special signals from
each tower initiates readout Function did
anything happen? keep as
simple as possible

• flexible, loose cuts
• The FSW filter code is wrapped and embedded in
  the full detector simulation
• leak a fraction of otherwise-rejected events to
  the ground for diagnostics, along with events ID
  for calibration

signal/background can be tuned
? rate a few Hz
Combinations of trigger primitives
Total Downlink Rate lt400 Hzgt
On-board science analysis transient detection
(bursts)
Upon a trigger, all subsystems are read out in
27ms
Spacecraft
Instrument Total Rate lt5 kHzgt
6
Trigger and Filter Rates Summary
Trigger
Filter

• Operating daily-average rate is 2.9kHz
• Peak rate is 6 kHz (watch deadtime)
• For this simulated day, 201 minutes spent in SAA
  (14).

• Gamma filter rate in this configuration is 360 Hz
• Pass any event w/ Egt20 GeV 40 Hz
• Plus other filters for mips and heavy ions
• Handles to reduce this rate significantly if
  needed

7
Reconstruction Overview

• Goal of the reconstruction
• Determine the incident gamma direction and energy
• Provide tools for suppressing background
• Follow a two pass approach for Cal and Tracker
• Best energy from Calorimeter needs tracking
  information
• Best tracks from Tracker needs best energy
  reconstruction
• Solve by breaking into two passes
• Background suppression
• ACD Recon
• MIP Finder
• Analysis step at end of reconstruction
• Create output ntuple for detailed performance
  studies
• Event Classification
• Create FT1 output for analysis

8
Event Reconstruction
Add up the energy in all the crystals(can be an
underestimate)
Raw Calorimeter Response
Track Pattern Recognition and Fitting (Kalman
Filter)
Use calorimeter cluster energy and position to
help find the tracks
Refined Calorimeter Response
Combine tracks to find gamma candidates
Track Refitting
ACD Analysis
Vertex Finding
9
The Illustrated Tracker Reconstruction
Tkr Clustering Associate adjacent hit strips to
form strip clusters (corrected for hot and dead
strips)
Pattern Recognition Associate strips to form
candidate tracks (Combinatoric pattern
recognition using Kalman Filter to accept/reject
candidate hits)
Track Fit Take candidate tracks and track energy
estimate and fit using a Kalman Filter
Vertexing Combine fit tracks to form common
vertex point- If one track, vertex is head of
track - If two tracks dont combine well, keep
as separate vertices
10
Measuring the Event Energy
1-GeV g
Thin-converter hits
Gap dead material between tracker towers
Thick-converter hits
Blank-converter hits
Energy lost in tracker
Gap between CAL towers
Calorimeter crystals
Energy lost in CAL
Leakage out the back of the CAL
11
Measuring the Energy Deposit in the Calorimeter

• Three methods
• Parametric Correction (can be used for any track)
• Use the tracks to characterize the shower
• Position, angle
• radiation lengths traversed
• Proximity to gaps
• Correct raw energy
• Likelihood (limited energy and angular range)
• uses relation between energy deposit in last
  layer and in the rest of the shower. Below about
  50 GeV, last-layer energy is proportional to the
  leaked energy.
• Profile Fitting (limited angular range)
• Fit layer-by-layer deposit to shower shape
• Best if shower peak is contained in CAL
• Choose best answer among available methods

12
ACD Analysis
Dots show intersection of tracks with planes of
ACD tiles.
The ACD has been measured to be 99.97 efficient
for minimum-ionizing particles. So whats most
interesting about the ACD is where it isnt! Dots
show intersection of tracks with planes of ACD
tiles. Because of gaps in the ACD coverage,
charged tracks may fail to produce a signal in
any tile. The ACD analysis identifies these gaps
to remove sources of background.
x
x
x
x
x
x
x
x
Because of backsplash, there may be struck tiles
that are not associated with the tracks.
Segmentation of the ACD allows us to salvage such
events.
We project the track back to the tiles, and ask
how close it comes to the nearest struck tile, if
any.
x
13
Post Reconstruction ProcessingThe Final Steps

• meritAlg
• Controls the creation of the merit output ntuple
• Used, for example, in various event
  classification analyses
• ClassifyAlg
• Runs the classification analysis
• Energy Selection
• PSF Tail suppression
• Background Rejection
• Classification Tree analysis
• Possibility to use alternate analyses as well
• FT1Alg
• Produce the Fits Level 1 output

14
LAT Performance
http//www-glast.slac.stanford.edu/software/IS/gla
st_lat_performance.htm
Energy dispersion
relative Aeff vs g angle at 10GeV
68 containment of the PSF
update before pre-launch package
Energy dispersion vs g angle
on-axis effective area
PSF vs g angle at 10GeV
15
LAT Scientific Performance
http//www-glast.slac.stanford.edu/software/IS/gla
st_lat_performance.htm
Differential sensitivity plot
Integral sensitivity plots

• Sensitivity is defined as the flux such that the
  log of the expected likelihood ratio for
  detection is 25/2 (or 5 sigma in the Gaussian
  case) and at least 5 photons.
• The assumptions are
• - one calendar year all-sky survey (including
  effects of the SAA and deadtime)
• diffuse background flux 1.5x10-5/cm2/s/sr (Egt100
  MeV) spectral index -2.1
• assuming a 1/E2 spectrum source at high latitude

16
Source and Background Flux

• Sky Simulation
• J.McEnery et al., GLAST symposium
• Galactic Diffuse
• AGN, GRB, DM
• Galactic populations (PSR, SNR, MuQSO)
• Extragalactic Diffuse
• Sun and Moon

• Background Flux
• J. Ormes et al., GLAST symposium
• Albedo ee- flux from AMS and Marya (but AGILE!)
• Primary cosmic proton flux
• New Albedo ? flux
• Waiting for PAMELA results

Black, total light green, GCR protons lavender,
GCR He red, GCR electrons blue, albedo protons
light blue, albedo positrons green, albedo
electrons and yellow albedo gammas.
17
The Gamma-Ray Sky

• Comparing EGRET to GLAST
• Illustrating the anticipated improvement in our
  knowledge of the sky

18
Science Tools
19
High-Level Analysis
Gamma rays in 1-day scanning observation (150k
gt30 MeV), color coded by energy
Annual rate (all energies) 108 gamma rays/year
Hundreds of sources even in this short time
What are their fluxes? Which are flaring?
Bright diffuse emission of the Milky Way
Galactic and extragalactic point source
populations
20
Mission Architecture
TDRS
TLM Ku-band _at_ 40 Mbps TLM S-band _at_ 1,2,4,8
kbps CMD S-band _at_ .25, 4 kbps
GLAST
White Sands Complex
RT HK Telemetry Command Data Science
HK Data Dumps Alerts/Alarms
Level 0 Data Contingency Command As-Flown
Timeline
Mission Operations Center
LAT Instrument Ops Center
Gamma-Ray Coordinates Network
Burst Messages
GSFC
SLAC
Level 0 Data Contingency Command
As-Flown Timeline Burst Messages
GSFC
Level 0 Data Observing Plan TOO Requests As-Flown
Timeline
Level 1/2 Data LAT Commands/Loads
Level 1/2 Data GBM Commands/Loads
GLAST Science Support Center
GBM Instrument Ops Center
Archive Data
Science Community
Science Products
GSFC
HEASARC
NSSTC
GSFC
21
Observations

• Concept GLAST can point anywhere, anytime.
• Survey Modethe default, designed for uniform sky
  exposure. The pointing is offset??30? from the
  zenith above and below the orbital plane. The
  offset is changed every orbit, giving a 2 orbit
  periodicity.
• Pointed Modeinertial pointing at a target. The
  Earth is kept out of the central 30? to avoid
  albedo gamma-rays.
• Pointed-Scan Modethe target is kept within the
  central 30? to maximize target exposure and avoid
  the Earth.
• Autonomous repointwhen the GBM or LAT detects a
  sufficiently bright burst, GLAST will repoint
  towards the burst location for 5 hours, except
  for Earth occultations.
• Target of Opportunity (TOO)repointing commanded
  from the ground in response to an astronomical
  event. Repointing should occur within 6 hours of
  the approval of the TOO.
• The mission data (science housekeeping) are
  downlinked 4-5 times per day through a 40 Mbps
  Ku-band TDRSS link

22
GLAST Science Support Center

• A component of the Office of Guest Investigator
  Programs (OGIP) in the Laboratory for High Energy
  Astrophysics (LHEA) at GSFC.
• Will not have a physical Guest Observer Facility
  (GOF) to which investigators come for assistance
  in analyzing data.
• In brief, the GSSC will
• Support the Guest Investigator Program
• Disseminate data, analysis tools and
  documentation to the science community
• Maintain the science timeline
• Vet IOC commands for impact on timeline
• Upon the Project Scientists approval, send ToO
  order to MOC
• Archive data in the HEASARC
• Support the Project (e.g., running conferences)

23
GSSC Website
24
Science Tools
http//www-glast.slac.stanford.edu/ScienceTools/re
views/sept02
The big picture Details are changing, but still
basically right
Standard Analysis Environment
25
LAT Science Analysis ToolsThe Standard Analysis
Environment

• The standard analysis environment consists of the
  tools and databases needed for routine analysis
  of LAT data.
• This environment will be used by both the LAT
  team and the general scientific community.
• This environment was defined jointly by the LAT
  team and the GSSC, but will be developed under
  the LAT teams management with GSSC
  participation.
• The analysis environment does not support all
  possible analyses of LAT data. Not included, for
  example
• Analysis of multi-gamma events or cosmic rays
• High-resolution spectroscopy
• Quick-look analysis
• Software for developing the point source catalog

26
Design Considerations

• The special challenges of analyzing LAT data
• The LAT will primarily operate in scanning mode
• Enormous FOV (gt2 sr)
• Response functions, in particular the PSF, depend
  on arrival direction in instrument coordinates
• Response functions will also depend on other
  parameters, such as conversion plane in the
  tracker
• So a given region will be observed with many
  different response functions

27
Design Considerations (2)
One days worth of LAT gamma rays

• Fluxes of celestial sources are low (1 ?/minute
  for a bright source), and the celestial
  background relatively bright (2.5 Hz over the
  FOV)
• Earth albedo ?-ray intensity is even brighter (30
  Hz if stare at limb)
• Charged particle background is extremely intense
  (few kHz rate)
• Relatively very poor angular resolution,
  especially on consideration of the tails and the
  density of sources

28
Design Considerations (3)

• Complicated data and reconstruction and
  classification of events underlay making the
  LAT a Telescope
• As for previous high-energy gamma-ray astronomy
  missions, the core high-level analysis will be
  model fitting, i.e., parametric analysis
• The analysis relies on an abstract
  characterization of the LAT via its response
  functions
• Models have discrete sources plus interstellar
  diffuse emission and isotropic emission
• Mixing of instrument coordinates with coordinates
  on the sky, owing to scanning, is one motivation
  to pursue unbinned likelihood analysis

T. Usher
29
Data Analysis Issues

• The PSF is large at low energy, small at high
  energy.
• With the LATs large effective area, many sources
  will be detected their PSFs will merge at low
  energy.
• Analysis is inherently 3D2 spatial and 1
  spectral ( users are interested in temporal!)
• For a typical analysis the source model must
  include
• All point sources within a few PSF lengths of the
  region of interest
• Diffuse sources (e.g., supernova remnants)
• Diffuse Galactic emission (modeled)
• Diffuse extragalactic emission
• Sources are defined by position, spectra, and
  perhaps time history. Initial values may be
  extracted from the point source catalog that will
  be compiled by the LAT team.
• The source model will have many parameters. In
  an analysis some will be fitted, some will be
  fixed.

30
Data Analysis Issues-II

• The instrument response (PSF, effective area,
  energy resolution) will most likely be a function
  of energy, angle to the LAT normal, conversion
  layer (the front or back of the LAT), and the
  electron-positron vertex angle. The IRF may also
  depend on the charged particle background
  resulting from the geomagnetic latitude, Solar
  cycle phase, etc.
• The LAT will usually survey the sky. Therefore a
  source will be observed at different instrument
  orientations.
• Pointed observations will keep the source of
  interest within 30 of normal.

31
Observables

• The observables for a photon are
• Apparent energy
• Apparent origin in sky coordinates (2
  observables)
• Apparent origin in instrument coordinates (2
  observables)
• Time
• Front vs. back of LAT
• Other detailed information from the LAT (e.g.,
  the vertex angle between the electron-positron
  pair)
• Therefore, a very large data space results.

32
Walkthrough of the SAE

• Schematic illustration of the data flow and how
  the tools relate to each other. Not all inputs
  (e.g., from user) are explicitly indicated
• Detailed descriptions of each component are
  available
• The tools identification scheme (letter
  number) is for convenience the distinction
  between U A can be subtle
• D database (in a general sense)
• U utility (supporting analyses)
• A analysis tool
• O observation simulation
• UI user interface (common aspects to utilities
  analysis tools)
• Common data types that can pass between tools are
  defined but not included in the diagram
• User Interface aspects of the SAE--such as
  Image/plot display, Command line interface
  scripting, and GUI Web access--are not shown
  explicitly in the diagram

33
Schematic of SAE
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Alternative source for testing high-level analysis
Alternative for making additional cuts on
already-retrieved event data
Interstellar em. model (U5)
Map gen(U6)
IRFs (D3)
Observation simulator (O2)
Data sub- selection (U2)
GRB unbinned spectral analysis (A9)
IRF visual- ization (U8)
Pt.ing/livetime simulator (O1)
Pt.ing/livetime extractor (U3)
GRB spectral-temporal modeling (A10)
GRB LAT DRM gen. (U14)
Note that some details have changed
GRB spectral analysis (A8)2
GRB visual- ization (U13)
GRB rebinning (A6)2
GRB temporal analysis (A7)2
GRB event binning (A5)
34
Event Data, Pointing Livetime History, and
Response Functions
Data extract (U1)
Level 1 (D1)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
IRFs (D3)
35
Event Display
Event display (UI1)
Level 0.5
Data extract (U1)
Data extract (U1)
Level 1 (D1)
Level 1 (D1)
Pt.ing/livetime extractor (U3)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Pointing/livetime history (D2)
IRFs (D3)
36
Exposure
Event display (UI1)
Level 0.5
Data extract (U1)
Level 1 (D1)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
IRFs (D3)
IRF visual- ization (U8)
37
Likelihood Analysis
Event display (UI1)
Level 0.5
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Interstellar em. model (U5)
IRFs (D3)
Multi-mission capabilities can be added to the
likelihood tool we will study whether such
analysis is computationally feasible.
IRF visual- ization (U8)
38
Point Source Catalog, Astronomical Catalogs,
Source Identification
Event display (UI1)
Level 0.5
LAT Point source catalog (D5)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Interstellar em. model (U5)
IRFs (D3)
IRF visual- ization (U8)
39
Pulsar Analyses
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Interstellar em. model (U5)
IRFs (D3)
IRF visual- ization (U8)
40
Map Generation
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Interstellar em. model (U5)
Map gen(U6)
IRFs (D3)
IRF visual- ization (U8)
41
Gamma-Ray Bursts
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Interstellar em. model (U5)
Map gen(U6)
IRFs (D3)
The burst analysis tools are designed to analyze
data from the GBM and other missions in addition
to (together with) the LAT.
GRB unbinned spectral analysis (A9)
IRF visual- ization (U8)
GRB spectral-temporal modeling (A10)
GRB LAT DRM gen. (U14)
GRB spectral analysis (A8)2
GRB visual- ization (U13)
GRB rebinning (A6)2
GRB temporal analysis (A7)2
GRB event binning (A5)
42
Alternative Data Sources
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Alternative source for testing high-level analysis
Alternative for making additional cuts on
already-retrieved event data
Interstellar em. model (U5)
Map gen(U6)
IRFs (D3)
Observation simulator (O2)
Data sub- selection (U2)
GRB unbinned spectral analysis (A9)
IRF visual- ization (U8)
Pt.ing/livetime simulator (O1)
Pt.ing/livetime extractor (U3)
GRB spectral-temporal modeling (A10)
GRB LAT DRM gen. (U14)
GRB spectral analysis (A8)2
GRB visual- ization (U13)
GRB rebinning (A6)2
GRB temporal analysis (A7)2
GRB event binning (A5)
43
All Together
Pulsar ephem. (D4)
Pulsar period search (A4)
Ephemeris extract (U11)
Event display (UI1)
Level 0.5
Pulsar profiles (A3)1
LAT Point source catalog (D5)
Pulsar phase assign (U12)
Arrival time correction (U10)
Data extract (U1)
Level 1 (D1)
Source model def. tool (U7)
Src. ID (A2)
Catalog Access (U9)
Exposure calc. (U4)
Pt.ing/livetime extractor (U3)
Pointing/livetime history (D2)
Likelihood (A1)
Astron. catalogs (D6)
Alternative source for testing high-level analysis
Alternative for making additional cuts on
already-retrieved event data
Interstellar em. model (U5)
Map gen(U6)
IRFs (D3)
Observation simulator (O2)
Data sub- selection (U2)
GRB unbinned spectral analysis (A9)
IRF visual- ization (U8)
Pt.ing/livetime simulator (O1)
Pt.ing/livetime extractor (U3)
GRB spectral-temporal modeling (A10)
GRB LAT DRM gen. (U14)
GRB spectral analysis (A8)2
GRB visual- ization (U13)
GRB rebinning (A6)2
GRB temporal analysis (A7)2
GRB event binning (A5)
44
Sequence of an Analysis Gamma-Ray Point Source

• Define region of sky, time range, etc. of
  interest
• Typical minimum size (based on PSF sizes) radius
  15
• Extract gamma-ray data (U1 accessing D1)
• Applying selection cuts, including zenith angle
• Typical data volume (per year) 1 106 ?-rays,
  108 bytes
• Generate exposure (U3 accessing D2)
• May better be called livetime accumulation, or
  precomputation for likelihood analysis
• Matches cuts applied to gamma-ray data
• Potential tabulation 700 grid points on sky
  15 energies 15 inclinations 15 zenith angle
  limits 2.5 106 values 107 bytes
• Define the model to be fit to the data (U7)
• Facilitated by candidate source catalog,
  intensity map and data visualization within U7
• Models may be considered as a table of
  parameters, or an XML file, human-readable,
  including parameters for interstellar emission
  model
• Typically will contain dozens of point sources
• Fit the model to the data, generating, e.g. TS
  maps and confidence regions or spectral fits
  (A1)
• Model may need refinement, iteration within A1

45
The user workbook
http//glast-ground.slac.stanford.edu/workbook/
ST pages
46
User Workbook ST
http//glast-ground.slac.stanford.edu/workbook/sci
ence-tools/sciTools_Home.htm
47
User Workbook Science Tools Tutorials
1
These tutorials help you on how to get the data,
make further selections and make simple binning
procedures to explore LAT data
48
Tutorial 1
At the end of the tutorial you should be able to
generate CMAP and LC from gtbin and learn how to
use gtselect and the data server at GSSC
49
User Workbook Science Tools Tutorials
2
These tutorials help you to analyze GLAST source
data. In particular you are guided to use the
Binned and Unbinned Likelihood analysis on a
particular sky region both at command interface
and with a Python UI
50
Tutorial 2
At the end of the tutorial you will be able to
perform likelihood analysis (binned and
unbinned) on specific region of the sky, making
cnts and src maps, exposure maps you should be
able to generate xml models of the sky regions
51
Galactic Diffuse Model
110 MeV

• Maps produced using GALPROP can be used by the
  GLAST simulation code.

1.2 GeV
52
User Workbook Science Tools Tutorials
2.1
This tutorials helps to identify a particular
source on the sky with data from external catalogs
53
User Workbook Science Tools Tutorials
3
These tutorials let you to do a spectral analysis
on GRB using GBM and LAT data. XSPEC is required.
54
Tutorial 3
The tutorial lets you to bin the GBM data and
perform joint spectral analysis with GBM and LAT
data.
55
User Workbook Science Tools Tutorials
4
These complete tutorials guide you in the
analysis of PSR data.
56
Tutorial 4
After the series of tutorials on PSR you will be
able to find the PSR period having applied
barycentric corrections and phase search using
ephemerides calculation
57
GRB analysis
58
Gamma-Ray Bursts include GBM
Omodei, Band, Connaughton
BGO
NaI(6)
LAT
Joint spectral fit using xspec
59
GRB analysis
Selecting the data
Compute the DRM
Spectral analysis
GBM data, rsp and back
Binning the data in Energy
Binning the data in Time
Light Curves
Binning the data in Location (ra, dec or l,b)
Sky Maps
Development of scripts (python, bash,) to drive
the analysis Integration with ftools and heasarc
software
60
GRB analysis

• GRB, transient source, GBM and LAT simulation,
• Time variation of the spectrum (pulse paradigm)

7 decades in energy
Combined signal from GBM (B0 N0) and LAT detectors
61
GBM
GCN Notices
Alert messages
LAT
10-15s
10-15s
Alert messages (1Alert lt10 Update 1Closeout)
T0
(Ground Analysis 10)
Paging System
Real Time Operations Found special GRB DS /
BA / Other (Telecon)
10-15s
Password Protected web page
1hr (30 Goal)
1st GCN Circular
ASP Automated Science Processing HSP Human
Science Processing
62
Pool of burst advocate

• Pool of burst advocate (was two per days in
  oktober test)
• Now making the one for the LEO 55 days

63
Example of GCN notices
64
Example of GCN notices
65
GLAST circular
66
ASP results
67
GLAST circular
68
GeV-TeV synergy

• ACTs 10 duty cycle, 5 fov. Some of them can
  slew in few minutes (20 of the sky)
• need 1 location accuracy (LAT only)
• Some back-of-the-envelope calculations
• Joint observation Number of LAT alerts duty
  cycle sky coverage
• ACT 50 0.1 0.2 1 - 5 GRB/yr suitable for
  combined GeV-TeV observations
• EAS 50 1 0.2 10 GRB/yr suitable for
  combined GeV-TeV observations