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Instrument Checkout / Performance Verification for XRT & Control of XRT Observation

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Instrument Checkout / Performance Verification for XRT & Control of XRT Observation

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  1. Instrument Checkout / Performance Verification for XRT&Control of XRT Observation R. Kano for the XRT Team

  2. Control of XRT Observation

  3. Mission Data Processor Observation Tables XRT SOT DR Image Compression Data Packet Edition Pre-Flare Buffers EIS Autonomous Functions AEC ARS FLD On-board functions for XRT Obs. Mission Data Processor (MDP) has many functions for XRT. • Management of XRT exposures by “Observation Table” • Autonomous Functions for XRT observations • Automatic Exposure duration Control (AEC) • Automatic Region Selector (ARS) • FLare Detection (FLD) • Image processing • Edition of Image data packets • Image compression • Pre-Flare Buffers

  4. Observation Table • XRT exposures are managed by one observation table in the Mission Data Processor (MDP). • The structure of XRT observation table is essentially the same with those for SOT. Observation Program (20 programs) Sequence Table (100 sequences) • Program No.1 • “Normal Obs.” • SUB1loop=10 • SUB3loop=1 • SUB2loop=10 • SUB3loop=1 • SEQ1: global structure of 1MK corona • Exp. for thin-Al-mesh & full FOV • Exp. for thin-Al-poly & full FOV • SUB1 • SEQ1loop=1 • SEQ2loop=20 • SEQ2: AR’s temperature structure • Exp. for thin-Al-poly & small FOV (AR) • Exp. for med-Be-mesh & small FOV (AR) • SUB2 • SEQ1loop=1 • SEQ3loop=20 • SEQ3: 1MK corona in AR • Exp. for thin-Al-mesh & small FOV (AR) • Exp. for thin-Al-poly & small FOV (AR) • SUB3 • SEQ100loop=1 : SEQ100: CCD dark calibration

  5. duration Automatic Exposure Control (AEC) Over Exposure Exposure duration is adjusted by using the intensity histogram. Number of pixel LLTULT If U is too much, shorten the exposure duration. IntensityI Normal Exposure Number of pixel LLTULT If L is not enough, lengthen the exposure duration. IntensityI Under Exposure Number of pixel LLTULT IntensityI

  6. Automatic Region Selector (ARS) • XRT will take an “ARS patrol image” (the full CCD-frame and 2”-resolution) once per orbit (every 90 min typically). • Two modes of ARS run in parallel each other. • “Global Search”mode to fine the brightest region. • “Local Search”mode to track bright regions.

  7. ARS: Global Search Steps to derive a new FOV • Take a new patrol image. • Define the search area.(The default is all CCD.) • Make a macro-pixel image. • Pick up the brightest macro-pixel. • Calculate a fine position in the original image around the selected macro-pixel. New FOV

  8. Automatic Region Selector (ARS) • XRT will take an “ARS patrol image” (the full CCD-frame and 2”-resolution) once per orbit (every 90 min typically). • Two modes of ARS run in parallel each other. • “Global Search”mode to fine the brightest region. • “Local Search”mode to track bright regions.

  9. ARS: Local Search Steps to derive a new FOV • Take a new patrol image. • Define the search area.(Just around the current FOV) • Calculate a fine position in the search area. Current FOV New FOV New FOV

  10. Flare Detection (FLD) • XRT will take a FLD patrol image every 30 sec (typically). • MDP derives a difference image between a new patrol image and the running averaged patrol image, and searches any intensity enhancement in it. • Once a flare occurred, MDP informs the flare position to SOT and EIS also. • (FLD function is useful to avoid strong irradiation to CCD.) FLD patrol image FLD patrol image FLD patrol image 30 sec (typically) 30 sec (typically) Averaged image Averaged image Averaged image Averaged image average average average difference difference difference Flare has detected! Flare is lasting. Flare has terminated.

  11. Pre-Flare Buffers Four buffers is available for the image transfer to the Data Recorder. • Buffer0 is prepared for the normal image transfer. • Buffer1, 2, and 3 for ring buffers to freeze the pre-flare images. Buffer0 Data Recorder Buffer1 “SW3” “SW1” Buffer2 Buffer3 “SW2” Total time X X−300s X−200s X−100s Buffer0 Buffer1 Buffer2 Buffer3

  12. Instrument Checkout&Performance Verification

  13. Detailed Items Launch Instrument checkout Front Door Opens Performance verification Science Obs. Starts

  14. Instrument checkout • Launch to Orbit Stabilization: ~ 3weeks • Turn on CCD heater and survival heaters just after the launch. • Survival mode until orbit is stabilized • Orbit Stabilization to Door Opening: ~ 1week • Turn on the electronics for XRT. • Functional tests (focus mechanism not tested. VLS not tested.) • CCD noise/dark characterization • Observation control check (partially)

  15. Performance verification • Door Opening and First Light: 1day • Door open (1day after the SOT top door open) • Initial X-ray and Visible light images • First Light to Science Ops: 1 ~ 3weeks • X-ray focus check and adjustment • Exposure duration check • Filter light leak check • Alignment check • Observation control check • Autonomous functions check • Automatic Exposure Control (AEC) • Automatic Region Selector (ARS) • FLare Detection (FLD)

  16. End, but.. Mercury Transit • Instrument • Alignment check. • Science • Sub-pixel structure?

  17. END

  18. To Control Observation To Control Onboard Process Observation Control (OBS CTL) AEC Control Table (AEC CTL) Current Control Table (CUR CTL) Filter Dimming Parameter Table (FLT) (internal table) Observation Program (OBS PRG) 20 programs ARS Control Table (ARS CTL) Sequence Table (SEQ) 100 sequences FLD Control Table (FLD CTL) Parameter Table (PAR) Region of Interest Table (ROI) AEC Thresholds Table (AET) Micro-Vibration Table (MVB) 100 tables 16 tables 7 tables Group Refer Observation Table (detail)