Science Mission Center

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Science Mission Center Burst Alert Network of
ECLAIRs

• Present the MIT contribution (SXCVHF) to the
  Science Mission Center
• Raise a list of questions about hardware,
  operations and performances of Burst Alert Network

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Science Mission Center (1/3)
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Science Mission Center (2/3)
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Science Mission Center (3/3)

• Modular architecture of automate allows
  sub-contraction (integration at CEA)
• Control screens located at Saclay
• Satellite monitoring (ground track, visibility by
  primary and VHF stations, position with respect
  to South Atlantic Anomaly, solar activity)
• Instrument monitoring (CXG SXC data, UDV
  observing conditions)
• Science results (gamma, x-ray and visible images
  and spectra)
• MIT contribution to Science Mission Center
• Develop modules for calibration monitoring of
  SXC (GRB analysis will be done on board by UTS)
• Handle Secondary science of SXC (secondary
  science of CXG will be handled by CESR)
• Build coherent VHF stream for GRB alert
• Transmit level 0 alert to GCN (higher level of
  alerts will be transmitted by CEA)
• SWIFT/HETE legacy
• Use of web technology for display in order to
• Make control screens available to associated
  laboratories
• Insure best scientific impact on the GRB
  community
• Duty scientists

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Burst Alert Network (1/4)
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Burst Alert Network (2/4)
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Burst Alert Network (3/4)
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Burst Alert Network (4/4)
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List of questions about Burst Alert Network

• References
• First Year Operation of the Burst Alert Network,
  2002, by J. Villasenor et al.
• Real-time message from the HETE spacecraft via
  the HETE Burst alert Network, 2002, by G.B. Crew
•   most stations are remotely monitored and
  maintained
• What are the needs ?
• What is the frequency of maintenance ?
• the signal demodulation and 3 kHz Doppler
  correction is carried out by hardware or by
  software solution developed at MIT
• Which is the best ?
• data corruption, varying local noise
  conditions
• Any statistics about that ?
• What kind of interfering source ?
• What is the visibility condition (angle above
  horizon) for each station ?
•  Fig 4 increasing SGS coverage with time,
  maximum at 80
• Any improvement after the first year operations ?
• What would be the expected coverage for ECLAIRs ?
•  Fig 5 transit travel time of few sec from
  message creation on board spacecraft to reception
  at the MIT control center
• What is the extra time before Saclay gets the
  message ?