# Presentation: 854880

## GLAST Burst Monitor

**Charles Meegan**
**Principal Investigator**
**NASA MSFC**
**Charles.Meegan@msfc.nasa.gov**
**Steve Elrod**
**Project Manager**
**NASA MSFC**
**Steve.Elrod@msfc.nasa.gov**

## 	The mission of the GLAST Burst Monitor (GBM) is to enhance the science return of the Gamma Ray Large Area Space Telescope (GLAST) mission in the study of gamma-ray bursts.  The GBM will detect bursts over a large solid angle and will continually measure the spectra of bursts over a wide energy band and with high temporal resolution.  It will also determine the directions to the bursts to allow optional repointing of the observatory.

**GBM Mission Statement**

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## GBM Management and Science Team

**Principal Investigator - Dr. Charles Meegan, MSFC**
**Co-Principal Investigator - Dr. Giselher Lichti, MPE**
**Project Manager - Stephen Elrod, MSFC**
**Systems Engineer - Fred Berry, MSFC**
**Co-Investigators (MSFC) - Dr. Jerry Fishman, Dr. Chryssa Kouveliotou**
**Co-Investigators (MPE) - Dr. Robert Georgii, Dr. Andreas von Keinlin, Dr. Roland Diehl, Dr. Volker Schönfelder**
**Co-Investigators (UAH) - Dr. William Paciesas, Dr. Geoff Pendleton, Dr. Robert Preece, Dr. Marc Kippen, Dr. Michael Briggs**

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## Organizational Chart

**Project Manager**
- S. Elrod

**Principal Investigator**
- C. Meegan

**Co-PI**
**Flight Detectors**
- G. Lichti

**Procurement**

**MSFC**
**S & MA**

**Systems Engineer**
- F. Berry

**MSFC**
**Engineering Support**

**UAH**
**Co-Investigators**
- M. Briggs
- M. Kippen
- W. Paciesas
- G. Pendleton
- R. Preece

**MSFC**
**Co-Investigators**
- J. Fishman
- C. Kouveliotou

**MPE**
**Co-Investigators**
- R. Diehl
- R. Georgii
- A. von Keinlin
- V. Schönfelder

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## GBM Near Term Schedule

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## GBM Functional Block Diagram

- Data
-   Processing
- Unit (DPU)

- HVPS

- LVPS

- Spacecraft
-  Interface

- PMT

- NaI

- Cmd/Resp

- Science data

- PPS

- Ancillary Data

- 1 of 2

- 1 of 12

- Power

- Command

**...**

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## GBM Detector Concept Drawings

**BGO Detector**

**NaI Detector**

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## Mass Estimate for GBM

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## Power Estimate for GBM

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## GBM Requirements Verification

**GBM is using a standard MSFC Requirements, Verification and Compliance (RVC) database.**
**Each requirement is numbered and categorized.**
**Verification method and description captured on same page.**
**Compliance data either referenced or stored electronically in data base.**
**Non conformances summarized and referenced in database, and dispositioned by the GBM configuration control board.**

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## GBM Sample Verification Sheet

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## GBM System Level Performance Requirements

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## Effects of Requirements on Design

- Large Energy Range

- NaI & BGO Detectors

- Adequate Sensitivity

- Number & Size of Detectors

- Coarse Location

- Number & Placement
- of NaI Detectors

- Wide FOV

- DPU speed

- Good Timing

- Data Types

- Burst Alerts

- Telemetry Requirements

- Science Requirements

- Design Impacts

- Mass & Volume
- Constraints

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## GBM Detector Mounting

_**NaI detectors:**_
- The direction to any point in the sky within 120 degrees (TBC) of the +Z axis shall be <80 degrees (TBC) from the normal vectors of at least 3 unobstructed non-collinear NaI detectors, with 95% probability.  The goal is 4 unobstructed non-collinear detectors with 100% probability.  Solar panels are not considered to be an obstruction.
- The angle between the normals of any two NaI detectors shall be >25 degrees (TBC).
_**BGO Detectors: **_
- At least one unobstructed BGO detector must be visible from any point in the sky within 150 degrees (TBC) of the +Z axis, with 95 % probability.  The goal is 100% probability over all directions.  Solar panels are not considered to be an obstruction.
- The axis of symmetry of the BGO detectors should be perpendicular to the Z axis.

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## GBM Detector Placement Concept

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## GBM Detector Performance Requirements

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## GBM DPU Performance Requirements

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## GBM Requirements Issues

**System linearity and stability need further study **
**DPU redundancy/cost trades**
**DPU/Spacecraft Interface**
- Small increase in telemetry buffer can achieve goal of science enhancement
- Max Spacecraft Bus Rate affects TTE Buffer
**Trigger alerts need to be coordinated with LAT team**
**Requirements levied on GLAST project**
- Observatory mass model
- Spacecraft simulator
- TBD spacecraft level radioactive source calibration
**Detector Mounting – **Thermal, FOV, Mechanical

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## GBM Ground Support System (pre-launch)

**Purpose**
- System test & calibration
- S/C integration & test
**Functions**
- Receive & store data
- Monitor detector rates, housekeeping, status
- Display & analyze detector spectra
- Generate & transmit instrument commands
- Simulate detector response

**Capabilities**
- Process/store >95% of real-time packets
- Transportability
- Critical custom components redundant
- DPU interface
- GLAST S/C interface
- S/C simulator required

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## GBM Ground Support System (post-launch)

**Purpose**
- Instrument operations
- Data archival
- Primary data analysis
**Functions**
- Process data, level 1  2
- Maintain flight S/W
- Monitor detector calibration
- Monitor detector rates, housekeeping, status
- Locate GRBs
- Deconvolve GRB spectra
- Mass Model required

**Instrument Operations Center**

**Functions (continued)**
- Generate/transmit instrument commands
- Compute GRB peak flux, fluence, duration
- Produce and deliver high-level data
- Interface to GLAST MOC/SSC
- Autonomous GRB location software for MOC

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