Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/external/xmm_sw_cal/icwg/presentations/Chandra_2_plucinsky.pdf Дата изменения: Mon Jun 19 12:26:40 2006 Дата индексирования: Sat Dec 22 15:15:24 2007 Кодировка: Поисковые слова: molecular cloud

Chandra X-Ray Observatory

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ACIS Calibration: Strategy, Implementation & Status

Paul Plucinsky
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Chandra X-Ray Observatory

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Bautz etal Fig 2 1998

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Chandra X-Ray Observatory
I: ACIS Pre-launch Calibration

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Absolute QE: reference CCDs calibrated at BESSY (see Bautz etal. 2000) - the parameters (thickness of gate structure components, depletion depth) of the CCD response model were varied until an acceptable fit to the BESSY ``white light'' spectrum was achieved - reference CCDs returned to MIT lab to be used as transfer standard for flight CCDs ACIS Calibration Report Table 4.28

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Chandra X-Ray Observatory
I: ACIS Pre-launch Calibration
Bautz etal 1998 Fig 7

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I: ACIS Pre-launch Calibration

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Spectral Redistribution Function: Prigozhin 1998, Bautz etal 2000, Prigozhin 2000

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Chandra X-Ray Observatory
I: ACIS Pre-launch Calibration
OBF Calibration: transmission maps at Wisconsin synchrotron (Townsley etal. 1996) and detailed transmission at Brookhaven (see Chartas etal. 1996) Instrument Thermal Vac: at MIT Lincoln Laboratories - flight CCDs integrated with flight electronics (noise, gain) - verify performance of flight SW

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- verify instrument performance at cold operating temperatures and after several thermal cycles X-ray Calibration Facility (XRCF) at NASA MSFC - measurements with HRMA and gratings, first experience with sharply focused images and the effects of pileup -after HRMA left, flat-field measurements with XRCF source system Integrated Science Instrument Module (ISIM) Thermal Vac at Ball: -verify instrument after integration on ISIM - first measurements of external calibration source at -120 C
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I: ACIS Pre-launch Calibration

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Highlights of Results Absolute QE of CCDs - known to better than 5.0% in the 0.3-4.0 keV band QE Uniformity - FI CCDs uniform to 2% on 32X32 pixel regions Energy Scale - FI CCDs known to better than < 0.1 % Spectral redistribution - FWHM of FI CCDs known to better than < 5.0% OBF transmission - known to better than 1.0% in the 0.3-3.0 keV band except around EXAFS OBF uniformity - uniform to 2% at 0.273, 0.522, and 0.775 keV HRMA/ACIS Effective Area - XRCF measurements consistent with the model to within 12% in the 0.5-9.0 keV range in the absence of pileup

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Chandra X-Ray Observatory
II: ACIS Post-launch Calibration
Two Major Changes to the Instrument: - radiation damage of the FI CCDs produced a large increase in CTI (Prigozhin etal. 2000, Townsley etal. 2000, Townsley etal. 2002, Grant etal. 2004)

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- contamination layer on the OBF (Vikhlinin 2004, Marshall etal. 2004, Plucinsky etal. 2003, 2004)

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Chandra X-Ray Observatory
II: ACIS Post-launch Calibration
- CTI correction recovers some of the lost spectral resolution - contamination correction has a temporal and spatial dependence - weighted responses for both BI and FI CCDs

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subarray

Node 1, high chipy

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Chandra X-Ray Observatory
II: ACIS Post-launch Calibration

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S3

I3

S3

I3

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Chandra X-Ray Observatory
Monitoring with the ECS (Grant etal. 2005)

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FI CTI 2.5%/yr

I3 Gain

BI CTI 0.5%/yr

I2 Gain

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Chandra X-Ray Observatory
II: ACIS Post-launch Calibration

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Current Status: Energy Scale - I array and S2, S3 CCDs known to better than < 0.3 % for most regions from 1.5-6.0 keV Spectral redistribution - FWHM of CCDs known to better than < 10.0% QE uniformity - uncertainty less than 1.0% in a 1 arcminute region, less than 5.0% across the detectors HRMA/ACIS Effective Area - uncertainties are less than 10% in the 1.5-6.0 keV band

III: Lessons Learned
1) 2) 3) need immediate, simple on-orbit verification of instrument performance contamination control and mitigation ground calibration needs to be as close to the on-orbit conditions as possible

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