A lobster-eye on the x-ray sky
- Code 662, Laboratory for High Energy Astrophysics, Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)
We propose an x-ray all-sky monitor for the International Space Station (ISS) that will be ten times more sensitive than past monitors and that opens up a new band of the soft x-ray spectrum (0.1 -3.0 keV) for study. Taking advantage of the power telemetry and space available on the ISS we can use a telescope geometry and detectors that will provide better than 4 arc minute resolution of the entire sky in a 1.5 hr duty cycle. To achieve this sensitivity and resolution we use focusing optics based on the lobster-eye geometry. We propose two approaches to the construction of the optics. The first method, well within the reach of existing technology, is to approximate the lobster-eye geometry by building crossed arrays of planar reflectors, this gives great control over the reflecting surface but is limited in terms of resolution at the baseline 4 arc minute level. The second method is to use microchannel plates: this technology has the potential to greatly exceed the baseline resolution and sensitivity but is yet to be fully demonstrated. A simultaneous development of both approaches with selection of the superior candidate at the end of the development phase is suggested. The instrument is made of a number of modules based on a 2x2 cooled CCD detector array that covers an area of 6x6 cm{sup 2} at the focal plane. Using optics with a radius of curvature of 0.75 m this gives each module a field of view of 9 deg. x 9 deg. The modular approach gives us enormous flexibility in terms of physical arrangement on the ISS so that we may take advantage of clear lines of sight and also in terms of built-in redundancy. We estimate that {approx}50 such modules give us instantaneous coverage of 1/10 of the sky. The scientific case for this mission is almost too broad to state here. The instrument we describe will allow investigation of the long term light curves of thousands of AGN, it will detect thousands of transients, including GRBs and type II supernova, and the stellar coronae of hundreds of the brightest x-ray stars can be monitored. In addition the classical objectives of all-sky monitors--long-term all-sky archive and watchdog alert to new events--will be fulfilled at an unprecedented level. We also note that by opening up a little-explored band of the x-ray sky the opportunity for new discovery is presented. A satisfying example of entering new territory while still retaining the guarantee of expanding the domain of existing research.
- OSTI ID:
- 21202516
- Journal Information:
- AIP Conference Proceedings, Vol. 458, Issue 1; Conference: Space technology and applications international forum - 1999, Albuquerque, NM (United States), 31 Jan - 4 Feb 1999; Other Information: DOI: 10.1063/1.57683; (c) 1999 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Next generation x-ray all-sky monitor
Related Subjects
CHARGE-COUPLED DEVICES
CONTROL
COSMIC PHOTONS
COSMIC RAY DETECTION
COSMIC X-RAY SOURCES
GAMMA ASTRONOMY
INTERNATIONAL SPACE STATION
KEV RANGE
MICROCHANNEL ELECTRON MULTIPLIERS
RADIATION MONITORS
RESOLUTION
SENSITIVITY
SOFT X RADIATION
STELLAR CORONAE
SUPERNOVAE
TELEMETRY
TELESCOPE COUNTERS
X-RAY DETECTION
X-RAY SPECTRA