instrument checkout / performance verification for xrt & control of xrt observation r. kano for...
TRANSCRIPT
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 ImageCompression
Pre-FlareBuffers
Autonomous Functions
FLDARSAEC
XRTObservationTables
Data PacketEdition
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=102. SUB3 loop=13. SUB2 loop=104. 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)
SUB11. SEQ1 loop=12. SEQ2 loop=20
SUB21. SEQ1 loop=12. SEQ3 loop=20
SUB31. 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
Num
ber
of p
ixel
)(IF
LLT ULT
Intensity I
Num
ber
of p
ixel
)(IF
4095
ULT
)(I
IFU
LLT ULT
Intensity I
Num
ber
of p
ixel
)(IF
4095
LLT
)(I
IFL
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 FOVNew FOVNew FOV
30 sec (typically) 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 difference difference
average averageaverage
Flare has detected!
Flare is lasting.
Flare has terminated.
FLD patrol image FLD patrol image FLD patrol image
Averaged image Averaged image Averaged image Averaged image
Pre-Flare Buffers
Buffer0
Buffer1
Buffer2
Buffer3
“SW1”
“SW2”
“SW3”
XX−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..
END
Observation Table (detail)
ObservationProgram
(OBS PRG)
SequenceTable(SEQ)
ParameterTable(PAR)
Region of InterestTable(ROI)
AEC ThresholdsTable(AET)
AEC ControlTable
(AEC CTL)
ARS ControlTable
(ARS CTL)
FLD ControlTable
(FLD CTL)
20 programs
100 sequences
100 tables 16 tables 7 tables
Filter Dimming Parameter Table
(FLT)
ObservationControl
(OBS CTL)
Current ControlTable
(CUR CTL)
Micro-VibrationTable(MVB)
To Control Observation To Control Onboard Process
Group Refer
(internal table)