GLAST LAT Project Adapted From Merriam Websters calibrate

GLAST LAT Project Adapted From Merriam Webster’s cal-i-brate 1. 2. To standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors to ascertain the caliber of (degree of mental capacity or moral quality of , degree of excellence or importance of) Face to Face IDT Meeting May 30 -31 2002 Face to Face IDT meeting May 30 -31 2002 SVAC on orbit Activities E. do Couto e Silva Outline Pre Launch calibrations – May 30 Post Launch calibrations – May 31 • Overview • SVAC Plan LAT-MD-00446 -03 • Data Taking modes • Post Launch SVAC Table E. do Couto e Silva 1

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 Summary of the splinter meeting (May 30) • Scope of the SVAC Plan – LAT-MD-00446 will be the only Calibration Plan and will address ground and on-orbit calibrations, where the latter will depend on the input and leadership of IOC • Feedback from subsystems – Due by June 6 to Ed Washwell, who will coordinate a meeting on June 7 to discuss implementation of suggestions (mostly on ground calibrations) • Ground calibrations – Next release will be accompanied by a DCN and signatures and will be used as a reference for implementation of ground calibrations. E. do Couto e Silva 2

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 Mission Phases Definitions are from LAT-TD-00501 “LAT Mission Phases” • Phase 0 – Launch and early orbit operations (I&T) • Phase 1 – Verification and all-sky survey • Phase 2 to 5 – Science Observations • Termination Phase – Re-entry E. do Couto e Silva 3

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 Should we have 2 or 3 special calibration modes? (Science Verification occurs during normal data taking mode) 1. Galactic Cosmic Rays (GCR) – require tracks the cross at least TBD layers – needs filtering algorithms – expect 10000 (TBR) events per tower to be sufficient to do calibrations C 2 to C 26 2. Charge Injection (CI) – Do we need this mode for ACD and CAL pedestals, TKR dead and noisy channels, TKR threshold scans, TKR TOT ? 3. ACD side tiles (AST) – D. Thompson brought up the point that side tiles need to be calibrated with large angle (from zenith) stiff tracks. Need 1000 (TBR) events crossing each tile for calibration C 1 E. do Couto e Silva 4

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 From LAT-MD-00446 I&T SVAC Plan Post launch Please revise FREQUENCY and PROCESSING scheme This input from subsystems is needed to have a first pass with flight software and IOC E. do Couto e Silva 5

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 On orbit rates • For each calibration item, Flight software and IOC need to estimate – Input Rate – Data Volume – Data Processing Rate – Downlink Rate • Need feedback from subsystems for each calibration item (just an educated guess for the moment) on the – Calibration mode to be used – Data processing scheme (on board or on the ground) – Expected frequency of calibrations during normal operations E. do Couto e Silva 6

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 CAL on orbit calibration How many events do we need and how often do we calibrate ? E. do Couto e Silva 7

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 On orbit calibration 1 ( from S. Ritz) Reviewed by I&T Committee Meeting June 1, 2001 Present: Tony, Martin, Scott Williams, Scott Sawyer, Eduardo, Hartmut, Bob Hartman, Steve, Tune Also sent to: Dave Thompson, Dave Bertsch, Seth Digel, Peter Michelson E. do Couto e Silva 8

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 On orbit calibration 2 ( from S. Ritz) Reviewed by I&T Committee Meeting June 1, 2001 Present: Tony, Martin, Scott Williams, Scott Sawyer, Eduardo, Hartmut, Bob Hartman, Steve, Tune Also sent to: Dave Thompson, Dave Bertsch, Seth Digel, Peter Michelson E. do Couto e Silva 9

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 Status of Previous tables • Alignment – Already in LAT-MD-00446 – Can Hiro Tajima draft an overall alignment plan ? • Energy Scales – Already in LAT-MD-00446 – Need to consolidate all existing information afater next release of LAT-MD-00446 • L 1 T efficiencies and Science Verification – Very little in LAT-MD-00446, need to concentrate the effort on that for the next month E. do Couto e Silva 10

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 Additional Thoughts • • • How much time do we have allocated for Phase 0 and Phase 1 ? Phase 0 – Develop standard monitoring and calibration procedures for subsequent phases – Phase 0 will have very frequent calibrations – Do we need to prioritize the list of calibrations ? (e. g if we have a GRB what do we need to be ready to verify the requirement on the time to notify the spacecraft and the location of the GRB ? – Do we expect calibration changes within one orbit ? – If we turn HV down during SAA, can these have any effect on calibrations right after we come back from SAA ? How long should we wait before resuming calibrations ? – Is during this phase that we verify source location and point source sensitivity ? – Prior to Phase 1 we should review the Calibration Plan Phase 1 – Nominal calibration and monitoring frequencies – All-sky survey E. do Couto e Silva 11

GLAST LAT Project Face to Face IDT Meeting May 30 -31 2002 How do we proceed ? • Next release of LAT-MD-00446 with signatures – June 10 • “Guesstimates” for on-orbit frequency and data taking mode from subsystems for C 1 to C 26 – June 18 • Eduardo will coordinate implementation of suggestions in consultation with IOC, JJ and Steve and report to IDT meeting on June 25 • Hiro Tajima with consultation with Steve will produce a draft of the alignment Plan – July 2 • IOC (? ) will report on IDT on July 2 explaining how to proceed with the on-orbit calibrations (especially L 1 T efficiencies and Science Verification) E. do Couto e Silva 12