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We present high-resolution X-ray spectra of the multiple (hierarchical quadruple) weak-lined T Tauri star system HD 98800, obtained with the High Energy Transmission Grating Spectrograph (HETGS) on board the Chandra X-Ray Observatory. In the zeroth-order Chandra/HETGS X-ray image, both principle binary components of HD 98800 (A and B, separation 0.["]8) are detected; component A was observed to flare during the observation. The infrared excess (dust disk) component, HD 98800B, is a factor of ~4 fainter in X-rays than the apparently "diskless" HD 98800A in quiescence. The line ratios of He-like species (e.g., Ne IX and O VII) in the HD 98800A spectrum indicate that the X-ray-emitting plasma around HD 98800 is in a typical coronal density regime (log n [less than or equal to] 11). We conclude that the dominant X-ray-emitting component(s) of HD 98800 is (are) coronally active. The sharp spectral differences between HD 98800 and the classical T Tauri star TW Hya demonstrate the potential utility of high-resolution X-ray spectroscopy in providing diagnostics of pre-main-sequence accretion processes., Chandra X-ray Observatory (U.S.) (Contract SV3- 73016), Chandra X-ray Observatory (U.S.) (HETG) (Contract NAS8-01129)

Details of the design, fabrication, and ground and flight calibration of the High Energy Transmission Grating (HETG) on the Chandra X‐Ray Observatory are presented after 5 years of flight experience. Specifics include the theory of phased transmission gratings as applied to the HETG, the Rowland design of the spectrometer, details of the grating fabrication techniques, and the results of ground testing and calibration of the HETG. For nearly 6 years the HETG has operated essentially as designed, although it has presented some subtle flight calibration effects., United States. National Aeronautics and Space Administration. George C. Marshall Space Flight Center (Contract NAS8-38249), United States. National Aeronautics and Space Administration. George C. Marshall Space Flight Center (Contract NAS8-01129)

The recently released Chandra Transmission Grating Catalog and Archive, TGCat, presents a fully dynamic on-line catalog allowing users to browse and categorize Chandra gratings observations quickly and easily, generate custom plots of resulting response corrected spectra on-line without the need for special software and to download analysis ready products from multiple observations in one convenient operation. TGCat has been registered as a VO resource with the NVO providing direct access to the catalogs interface. The catalog is supported by a back-end designed to automatically fetch newly public data, process, archive and catalog them, At the same time utilizing an advanced queue system integrated into the archive's MySQL database allowing large processing projects to take advantage of an unlimited number of CPUs across a network for rapid completion. A unique feature of the catalog is that all of the high level functions used to retrieve inputs from the Chandra archive and to generate the final data products are available to the user in an ISIS written library with detailed documentation. Here we present a structural overview of the Systems, Design, and Accessibility features of the catalog and archive., United States. National Aeronautics and Space Administration (Chandra X-ray Center (CXC) NASA contract NAS8-03060), United States. National Aeronautics and Space Administration (Smithsonian Astrophysical Observatory (SAO) contract SV3-73016 for the Chandra X-Ray Center and Science Instruments)

We present high-resolution X-ray spectra of the multiple (hierarchical quadruple) weak-lined T Tauri star system HD 98800, obtained with the High Energy Transmission Grating Spectrograph (HETGS) on board the Chandra X-Ray Observatory. In the zeroth-order Chandra/HETGS X-ray image, both principle binary components of HD 98800 (A and B, separation 0.["]8) are detected; component A was observed to flare during the observation. The infrared excess (dust disk) component, HD 98800B, is a factor of ~4 fainter in X-rays than the apparently "diskless" HD 98800A in quiescence. The line ratios of He-like species (e.g., Ne IX and O VII) in the HD 98800A spectrum indicate that the X-ray-emitting plasma around HD 98800 is in a typical coronal density regime (log n [less than or equal to] 11). We conclude that the dominant X-ray-emitting component(s) of HD 98800 is (are) coronally active. The sharp spectral differences between HD 98800 and the classical T Tauri star TW Hya demonstrate the potential utility of high-resolution X-ray spectroscopy in providing diagnostics of pre-main-sequence accretion processes., Chandra X-ray Observatory (U.S.) (Contract SV3- 73016), Chandra X-ray Observatory (U.S.) (HETG) (Contract NAS8-01129)

High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5 arcsecond half power diameter telescope point-spread function of the International X-ray Observatory will present unprecedented opportunity for a grating spectrometer to address these areas at the forefront of astronomy and astrophysics. We present the current status of a transmission grating spectrometer based on recently developed high-efficiency critical-angle transmission (CAT) gratings that combine the traditional advantages of blazed reflection and transmission gratings. The optical design places light-weight grating arrays close to the telescope mirrors, which maximizes dispersion distance and thus spectral resolution and minimizes demands on mirror performance. It merges features from the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer, and provides resolving power R = E/ΔE = 3000 - 5000 (full width half max) and effective area >1000 cm[superscript 2] in the soft x-ray band. We discuss recent results on ray-tracing and optimization of the optical design, instrument configuration studies, and grating fabrication., United States. National Aeronautics and Space Administration (NNX07AG98G), United States. National Aeronautics and Space Administration (NNX08AI62G), United States. National Aeronautics and Space Administration (NNX09AE82A)

High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5 arcsecond half power diameter telescope point-spread function of the International X-ray Observatory will present unprecedented opportunity for a grating spectrometer to address these areas at the forefront of astronomy and astrophysics. We present the current status of a transmission grating spectrometer based on recently developed high-efficiency critical-angle transmission (CAT) gratings that combine the traditional advantages of blazed reflection and transmission gratings. The optical design places light-weight grating arrays close to the telescope mirrors, which maximizes dispersion distance and thus spectral resolution and minimizes demands on mirror performance. It merges features from the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer, and provides resolving power R = E/ΔE = 3000 - 5000 (full width half max) and effective area >1000 cm[superscript 2] in the soft x-ray band. We discuss recent results on ray-tracing and optimization of the optical design, instrument configuration studies, and grating fabrication., United States. National Aeronautics and Space Administration (NNX07AG98G), United States. National Aeronautics and Space Administration (NNX08AI62G), United States. National Aeronautics and Space Administration (NNX09AE82A)

We present a high-resolution soft x-ray grating spectrometer concept for the International X-Ray Observatory (IXO) that meets or exceeds the minimum requirements for effective area (> 1, 000 cm[superscript 2] for E < 1 keV) and spectral resolution (E/[open triangle]E > 3, 000). At the heart of the spectrometer is an array of recently developed highefficiency blazed transmission gratings, the so-called critical-angle transmission (CAT) gratings. They combine the advantages of traditional transmission gratings (very low mass, extremely relaxed alignment and flatness tolerances) with those of x-ray reflection gratings (high efficiency due to blazing in the direction of grazing-incidence reflection). In addition, a CAT grating spectrometer is well-suited for co-existence with energy-dispersive highenergy focal plane detectors, since most high-energy x rays are neither absorbed, nor diffracted, and contribute to the effective area at the telescope focus. Since our initial successful x-ray demonstrations of the CAT grating concept with large-period and lower aspect-ratio prototypes, we have now microfabricated 200 nm-period silicon CAT gratings comprised of grating bars with the required dimensions (6 micron tall, 40 nm wide, aspect ratio 150), optimized for the 0.3 to 1.0 keV energy band. Preliminary analysis of recent x-ray tests show blazing behavior up to 1.28 keV in accordance with predictions., National Aeronautics and Space Administration (grants NNX07AG98G, NNX08AI62G, and NNX09AE82A), Kavli Foundation

We present a high-resolution soft x-ray grating spectrometer concept for the International X-Ray Observatory (IXO) that meets or exceeds the minimum requirements for effective area (> 1, 000 cm[superscript 2] for E < 1 keV) and spectral resolution (E/[open triangle]E > 3, 000). At the heart of the spectrometer is an array of recently developed highefficiency blazed transmission gratings, the so-called critical-angle transmission (CAT) gratings. They combine the advantages of traditional transmission gratings (very low mass, extremely relaxed alignment and flatness tolerances) with those of x-ray reflection gratings (high efficiency due to blazing in the direction of grazing-incidence reflection). In addition, a CAT grating spectrometer is well-suited for co-existence with energy-dispersive highenergy focal plane detectors, since most high-energy x rays are neither absorbed, nor diffracted, and contribute to the effective area at the telescope focus. Since our initial successful x-ray demonstrations of the CAT grating concept with large-period and lower aspect-ratio prototypes, we have now microfabricated 200 nm-period silicon CAT gratings comprised of grating bars with the required dimensions (6 micron tall, 40 nm wide, aspect ratio 150), optimized for the 0.3 to 1.0 keV energy band. Preliminary analysis of recent x-ray tests show blazing behavior up to 1.28 keV in accordance with predictions., National Aeronautics and Space Administration (grants NNX07AG98G, NNX08AI62G, and NNX09AE82A), Kavli Foundation