&lt;title&gt;Toward the calibration of the HETGS effective area&lt;/title&gt;

Dewey, Daniel; Flanagan, Kathryn A.; Marshall, Herman L.; Baluta, Chris; Canizares, C. R.; Davis, David; Davis, John E.; Fang, Taotao; Huenemoerder, David P.; Kastner, Joel H.; Schulz, Norbert S.; Wise, Michael; Drake, J. J.; Juda, Jiahong Zhang; Juda, M.; Brinkman, A. C.; Gunsing, C. J. T.; Kaastra, J. S.; Hartner, Gisela; Predehl, P.

doi:10.1117/12.278843

Cited by 5 publications

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“…The detectors were mounted on a table which could be moved in all directions, FPC and SSD could be equipped with various apertures (see, e.g. Dewey et al 1997). Most of the LETG efficiency measurements were done with the FPC.…”

Section: Letgs Calibration Schemementioning

confidence: 99%

<title>X-ray calibration of the AXAF Low Energy Transmission Grating Spectrometer: effective area</title>

Predehl

Braeuninger

Brinkman

et al. 1997

Grazing Incidence and Multilayer X-Ray Optical Systems

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The Low Energy Transmission Grating Spectrometer (LETGS) on board the Advanced X-ray Astrophysics Facility provides high resolution dispersive spectroscopy between 70 eV and more than 7 keV. The LETG contains 180 grating modules, each equipped with 3 grating facets. The freestanding gold gratings have 1008 lines per mm.Early 1997, the AXAF telescope underwent extended calibrations in the long beam X-Ray Calibration Facility at the NASA! Marshall Space Flight Center. As part of the telescope, also the performmce of the LETGS with respect of spectral resolving power and effective area was measured. At more than 50 individual energies we have measured the grating efficiency or the effective area of the spectrometer, respectively. All these energies were chosen in order to cover the numerous spectral features due to absorption edges of filters, detector coatings, minor reflectivities, and grating efficieny variations. Although preliminary, the performance of the gratings is close to the predictions made on the basis of subassembly measurements of individual grating elements. In particular, the first order efficiency is about 15% (both sides including vignetting effects) outside the energy regime of partial transparency of the grating wires; inside the efficiency gains from constructive interference effects. Both first diffraction orders are symmetric within less than 1 %. The second order is supressed by a factor of about 200 relative to the first order.

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Section: Letgs Calibration Schemementioning

confidence: 99%

<title>X-ray calibration of the AXAF Low Energy Transmission Grating Spectrometer: effective area</title>

Predehl

Braeuninger

Brinkman

et al. 1997

Grazing Incidence and Multilayer X-Ray Optical Systems

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“…These disperse X-rays to the focal plane detector, which is usually the Advanced CCD Imaging Spectrometer (ACIS). 5 Ground-based calibration observations have been previously reported [6][7][8][9][10][11] and are summarized in the HETGS Ground Calibration Report † These reports provide detailed ground-based measurements and modeling of various aspects of the HETGS such as the line response function (LRF) and the grating efficiencies. Here, we report on analysis of many observations obtained with the HETGS during in-flight calibration and instrument checkout.…”

Section: Introductionmentioning

confidence: 99%

In-flight calibration of the Chandra high-energy transmission grating spectrometer

2004

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We present results from in-flight calibration of the High Energy Transmission Grating Spectrometer (HETGS) on the Chandra X-ray Observatory. Basic grating assembly parameters such as orientation and average grating period were measured using emission line sources. These sources were also used to determine the locations of individual CCDs within the flight detector. The line response function (LRF) was modeled in detail using an instrument simulator based on pre-flight measurements of the grating alignments and periods. These LRF predictions agree very well with in-flight observations of sources with narrow emission lines. Using bright continuum sources, we test the consistency of the detector quantum efficiencies by comparing positive orders to negative orders.

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“…19,20 The measurements designed for HETGS e ective area calibration were performed using a variety of x-ray sources and detectors in order to cover the whole e ective energy range with high resolution lines of su cient p o w er. 8 In this report we focus on measurements performed with the DCM, the EIPS, and the HiREFS covering a total energy range of 0.5 to 8.7 keV. During this phase H" of XRCF testing, the ACIS-S array was the only detector in the focal plane.…”

Section: Measurements At X R Cfmentioning

confidence: 99%

“…As a backup con guration the spectrometer could also operate with the High Resolution Camera HRC-I in the focal plane. Detailed descriptions of the HETGS have been given in previous SPIE conference proceedings, 8,12,13 but we also want to encourage the interested reader to consult the AXAF Observatory Guide 17 for a general overview of Chandra and the HETG web site see note below for up-to-date information about the HETGS. The 1998 SPIE conference proceedings 14 contain a preliminary version of this report.…”

Section: Introductionmentioning

confidence: 99%

Absolute effective areas of the HETGS

1998

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Absolute e ective area measurements of the ight-con guration Chandra High-Energy Transmission Grating Spectrometer HETGS were performed at the X-ray Calibration Facility XRCF during Phase H testing. The results of these measurements are compared with e ective area predictions based on models of the individual HETGS components: the High Resolution Mirror Assembly HRMA, the High-Energy Transmission Grating HETG, and the AXAF CCD Imaging Spectrometer Spectroscopy array A CIS-S. The energy range from 0.48 to 8.7 keV was sampled at over 75 energies using x-rays produced by three of the sources available in the XRCF X-ray Source System XSS. The Double Crystal Monochromator DCM provided dense coverage of the range 0.9 keV to 8.7 keV; the High Resolution Erect Field grating Spectrometer HiREFS reference: speci cally HIREFS-SXR-1.75 grating monochromator from Hettrick Scienti c Inc. provided data points in the 0.48 keV to 0.8 keV range; and x-ray lines from several targets of the Electron Impact Point Source EIPS covered the range from 0.525 keV O-K to 1.74 keV Si-K. The absolute e ective area was measured as the ratio of the focal plane rate detected in a line to the line ux at the HRMA entrance aperture. A set of four Beam Normalization Detectors BNDs located around the HRMA were the prime source of ux determination. A variety of analysis techniques and considerations were applied including beam uniformity corrections, line deblending, and ACIS pileup. Uncertainties in the measurements are assigned based on counting statistics and estimates of analysis systematics; typically each measurement has an assigned error of order 10. The data indicate that we are very close to realizing our goal of a 10 absolute e ective area calibration for the rstorder e ective area. The measurement-model residuals are seldom outside a 20 range for both the High Energy Grating HEG and the Medium Energy Grating MEG rst-order areas. Systematic variation of the residuals appear at a level of -10 in the energy range below 1.3 keV; in the 2.5 keV to 5 keV range a consistent +3 to +7 over prediction is seen. The regions of greater systematic variation, 1.3 to 2.5 keV and above 5 k eV, are most likely dominated by uncompensated DCM beam uniformity e ects and ACIS grade migration e ects respectively.

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<title>Toward the calibration of the HETGS effective area</title>

Cited by 5 publications

References 0 publications

<title>X-ray calibration of the AXAF Low Energy Transmission Grating Spectrometer: effective area</title>

<title>X-ray calibration of the AXAF Low Energy Transmission Grating Spectrometer: effective area</title>

In-flight calibration of the Chandra high-energy transmission grating spectrometer

Absolute effective areas of the HETGS

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