Martin V. Zombeck

AXAF High-Resolution Camera (HRC): calibration and recalibration at XRCF and beyond

The high resolution camera (HRC) is a microchannel plate based imaging detector for the Advanced X-Ray Astrophysics Facility (AXAF) that will be placed in a high earth orbit scheduled for launch in August, 1998. An end-to-end calibration of the HRC and the AXAF high resolution mirror assembly (HRMA) was carried out at the Marshall Space Flight Centers X-Ray Calibration Facility (XRCF). This activity was followed by several modifications to the HRC to improve its performance, and a series of flat field calibrations. In this paper, and the following companion papers, we discuss the calibration plans, sequences, and results of these tests. At the time of this conference, the HRC has been fully flight qualified and is being integrated into the science instrument module (SIM) in preparation for integration into the AXAF spacecraft.

In-flight performance of the Chandra high-resolution camera

The High Resolution Camera (HRC) is one of the two focal plane instruments on NASAs Chandra X-ray Observatory which was successfully launched July 23, 1999. The Chandra Observatory will perform high resolution spectroscopy and imaging in the X-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. In this paper we present an overview of the in-flight performance of the High Resolution Camera and discuss some of the initial scientific results.

Orbital performance of the high-resolution imager (HRI) on ROSAT

The ROSAT (Roentgen Satellite) observatory was launched 1990 June 1, with a microchannel- plate-based high resolution imager (HRI) as one of the focal plane instruments of its primary soft x-ray telescope. Exhaustion of the gas supply for ROSATs other focal-plane detector has left the HRI as the sole instrument for continuing the program of celestial soft x ray observations. The long-term behavior of the HRI is presented, with descriptions of imaging performance, quantum efficiency and gain stability, spectral resolution, UV response, and background characteristics.

Metalized polyimide filters for x-ray astronomy and other applications

Filters fabricated from metalized polyimide have been specified for a number of x-ray astronomy missions, including the Advanced X-ray Astrophysics Facility (AXAF), the x-ray spectrometer (XRS) on Astro-E, the Advanced Composition Explorer (ACE), and the Geostationary Operational Environmental Satellite (GOES). Polyimide offers greater strength, improved temperature stability, and effectiveness in blocking unwanted ultraviolet radiation compared to polymeric films previously employed. This paper reviews the various x- ray astronomy missions and the particular challenges that were met with polyimide filters. The paper also reviews the development of free standing thin foils of polyimide with mechanical properties optimized for x-ray astronomy and other applications, such as synchrotron research.

High-resolution camera (HRC) on the Advanced X-Ray Astrophysics Facility (AXAF)

The Advanced X-ray Astrophysics Facility (AXAF) is a major NASA space observatory and is scheduled for launch in 1998. AXAF will perform high spatial and spectral resolution observations of celestial sources in the soft x-ray band 0.1 - 10 keV. The high resolution camera (HRC) is one of two focal plane instruments being developed for the AXAF. The HRC will be capable of observing point and extended sources with high sensitivity and high spatial resolution and will be used to record the high resolution spectra produced by an objective transmission grating. The HRC is based on microchannel plates (MCPs). We describe the design and development of the HRC, its expected performance, and some of its observational goals. The HRC consists of two separate detectors, HRC-I (imaging) and HRC-S (spectroscopy). HRC-I is used for imaging and has a field of view of 31 arc min by 31 arc min and a spatial resolution of less than 25 micrometers (equivalent to less than 0.5 arc sec). HRC- S is optimized to readout the spectrum of AXAFs low energy transmission grating (LETG) and this combination will achieve resolving powers in excess of 1000 at low energies and cover a wavelength range of 4 to 140 angstroms.

High Resolution X-Ray Scattering Measurements

The results of high angular resolution grazing incidence scattering measurements of highly polished, coated optical flats in the X-ray spectral range of 1.5 to 6.4 κeV are reported. The interpretation of these results in terms of surface microtopography is presented and the implications for grazing incidence X-ray imaging are discussed.

Advanced X-Ray Astrophysics Facility (AXAF)

The Advanced X-ray Astrophysics Facility (AXAF) is to be a free-flying national x-ray observatory that is Shuttle-launched (in mid-1988), maintainable on-orbit, and retrievable. The design lifetime is > 10 years. The AXAF is conceived as an x-ray telescope with 6 nested Wolter type I mirrors (maximum aperture of 1.2 m), a focal length of 10 m, and interchangeable and replaceable focal plane instruments. The optics will provide 0.5 arcsecond imagery over a several arcminute field and somewhat reduced resolution over 1 degree in the x-ray band from 0.1 to 8 keV. The performance requirements and design of the facility will be discussed and comparisons made with an existing x-ray observatory. The scientific objectives of the AXAF will also be discussed briefly.

In-flight Performance and Calibration of the Chandra High Resolution Camera Imager (HRC-I)

In this paper we present and compare flight results with the latest results of the ground calibration for the HRC-I detector. In particular we will compare ground and in flight data on detector background, effective area, quantum efficiency and point spread response function.

Performance and calibration of the AXAF High-Resolution Camera II: the spectroscopic detector

The high resolution camera (HRC) is one of two focal plane detector systems that will be flown on the Advanced X-ray Astrophysics Facility (AXAF). The HRC consists of two microchannel plate (MCP) detectors: one to provide large area, high position resolution imaging and timing (HRC-I), and a second (HRC-S) to provide a readout for the AXAF low energy transmission gratings. Each detector is composed of a chevron pair of CsI coated MCPs with a crossed grid charge detector and an Al/polyimide UV/ion shield. In this paper, we describe the operation, performance and calibration of the spectroscopic detector. In particular, we discuss the absolute quantum efficiency calibration, the point spread function of the instrument combined with the AXAF telescope, the count rate linearity, the spatial linearity, and the internal background of the instrument. Data taken in the laboratory and at the x-ray Calibration Facility at Marshall Space Flight Center are presented.

An Explanation of the ROSAT High-Resolution Imager Ultraviolet Sensitivity

The UV sensitivity to bright stars observed during operations of the high-resolution imager (HRI) on the X-ray-XUV Roentgen Satellite (ROSAT) has been commonly interpreted as a result of enhanced transmission solely in the wavelength range 1500-1700 A of the HRIs UV/ion shield. We report on recent laboratory UV transmission measurements of HRI flight spare filters that show transmissions much higher than previously assumed for wavelengths longward of approximately 2000 A. We present a model for the UV response of the HRI based on these measurements. Using this model and the known UV spectra of the A stars Vega (α Lyrae, V = +0.03) and β Carinae (V = +1.68), we successfully predict the observed HRI count rates for these two stars.