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

Control of XRT Observation

On-board functions for XRT Obs. Mission Data Processor DR Image Compression Pre-Flare Buffers Autonomous Functions FLDARSAEC XRT Observation Tables Data Packet Edition SOT EIS 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

Observation Table Program No.1 “Normal Obs.” 1.SUB1 loop=10 2.SUB3 loop=1 3.SUB2 loop=10 4.SUB3 loop=1 SEQ1: global structure of 1MK corona Exp. for thin-Al-mesh & full FOV Exp. for thin-Al-poly & full FOV SEQ2: AR’s temperature structure Exp. for thin-Al-poly & small FOV (AR) Exp. for med-Be-mesh & small FOV (AR) SEQ3: 1MK corona in AR Exp. for thin-Al-mesh & small FOV (AR) Exp. for thin-Al-poly & small FOV (AR) SEQ100: CCD dark calibration Sequence Table (100 sequences) Observation Program (20 programs) SUB1 1. SEQ1 loop=1 2. SEQ2 loop=20 SUB2 1. SEQ1 loop=1 2. SEQ3 loop=20 SUB3 1. SEQ100 loop=1 ： 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.

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

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.

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

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.

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

30 sec (typically) 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.) difference average Flare has detected! Flare is lasting. Flare has terminated. FLD patrol image Averaged image

Pre-Flare Buffers Buffer0 Buffer1 Buffer2 Buffer3 “SW1” “SW2” “SW3” X X−100sX−200sX−300s time Total Buffer0 Buffer1 Buffer2 Buffer3 Data Recorder 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.

Instrument Checkout & Performance Verification

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

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)

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)

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

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Observation Table (detail) Observation Program (OBS PRG) Sequence Table (SEQ) Parameter Table (PAR) Region of Interest Table (ROI) AEC Thresholds Table (AET) AEC Control Table (AEC CTL) ARS Control Table (ARS CTL) FLD Control Table (FLD CTL) 20 programs 100 sequences 100 tables16 tables7 tables Filter Dimming Parameter Table (FLT) Observation Control (OBS CTL) Current Control Table (CUR CTL) Micro-Vibration Table (MVB) To Control ObservationTo Control Onboard Process GroupRefer (internal table)