| 单词 | xmm | ||||||
| 释义 | XMMXMMAn X-ray mission, the second ‘cornerstone’ mission in the ESA Horizon 2000 space science program launched into an elliptical orbit (apogee 115 000 km, perigee 7000 km, period 48 hr) by Ariane 5 in December 1999. Three identical nests of grazing incidence telescopes, each of 7.5 meters focal length, provide effective areas (1500 cm2 at 6 keV and 4000 cm2 at 1 keV) larger than on any previous or contemporary payload, making XMM particularly well-suited to the study of faint galactic and extragalactic sources. The telescopes feed a combination of X-ray-sensitive CCDs and reflection gratings, with spectroscopy and deep X-ray imaging being primary observational goals. XMM also carries a co-aligned optical telescope which will be used to provide simultaneous visible and UV fluxes of the observed X-ray sources and is intended to operate in orbit for up to 10 years.XMMXMM
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