6/26/2023 0 Comments Spectrometer grating dispersio![]() If the instrument model is correct, the two RGS instruments should produce consistent results within the statistical uncertainty. With the simultaneous operations of two reflection grating spectrometer (RGS) instruments, we have an excellent tool for studying systematic errors. Apart from statistical fluctuations in the data, important scientific results also depend on understanding the systematic errors of the instrument. In addition, changes in the calibration due to the operational conditions in space (radiation damage, contamination, etc.) should be understood well and be taken into account. This understanding requires a profound knowledge of the limitations of the preflight calibrations and the models applied to calculate the response in orbit. ![]() Key words: instrumentation: spectrographs / instrumentation: detectors / techniques: spectroscopicĪccurate understanding of the instrument response is a prerequisite for correctly interpreting the observational data from XMM-Newton. Based on a large set of inflight calibration data and comparison with other instruments onboard XMM-Newton, the calibration accuracy of the RGS instrument has been improved considerably over the preflight calibrations. The remaining systematic uncertainty in the detection of weak absorption features has been estimated to be 1.5%.Ĭonclusions. Uncertainties in the instrument response have been reduced to <10% for the effective area and <6 mÅ for the wavelength scale (in the range from 8 Å to 34 Å). Physical models of the instrument are tuned to agree with calibration measurements and are the basis from which the actual instrument response can be interpolated over the full parameter space. Dedicated inflight measurements and constant monitoring are essential for a full understanding of the instrument and the variations of the instrument response over time. Ground calibrations alone are not able to fully characterize the instrument. This will be crucial for any correct scientific interpretation of spectral features for a wide variety of objects. By combining the preflight calibration with appropriate inflight calibration data including the changes in detector performance over time, we aim at profound knowledge about the accuracy in the calibration. We describe the calibration and in-orbit performance of the RGS instrument. Two identical RGS instruments are available, with each RGS combining a reflection grating assembly and a camera with charge-coupled devices to record the spectra.Īims. One of the instruments onboard XMM-Newton is the reflection grating spectrometer (RGS). XMM-Newton was launched on 10 December 1999 and has been operational since early 2000. Paerels 3ġ SRON Netherlands Institute for Space Research, SorbonnelCA Utrecht, The NetherlandsĮ-mail: European Space Agency, ESAC, Apartado 50727, 28080 Madrid, Spainģ Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027, USAĤ Astronomical Institute “Anton Pannekoek”, Science Park 904, University of Amsterdam, 1098 XH Amsterdam, The NetherlandsĬontext.
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