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  • 1
    Electronic Resource
    Electronic Resource
    Do comets provide material for the anomalous component of the cosmic rays? (1979)
    [s.l.] : Nature Publishing Group
    Nature 279 (1979), S. 622-624 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The spectra of the nucleonic component of cosmic radiation in the energy band 1-60 MeV per nucléon have produced a number of surprises. The most dramatic of these concerned the fluxes of oxygen and carbon. Jokipii1 gave minimum flux values in the region 5 MeV per nucléon for hydrogen ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/279622b0
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  • 2
    Electronic Resource
    Electronic Resource
    Attempt to detect X-ray Pulses from the Crab Nebula (1969)
    [s.l.] : Nature Publishing Group
    Nature 222 (1969), S. 149-150 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] During a balloon flight of a telescope on August 22, 1968, the X-ray spectrum from the Crab Nebula was measured in the energy interval 30 keV-120 keV, and the detector pulses were recorded on magnetic tape together with 1 kHz clock pulses from a crystal-controlled oscillator. The frequency of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/222149a0
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  • 3
    Electronic Resource
    Electronic Resource
    Short timescale variability of the mesospheric sodium layer (2000)
    Springer
    Experimental astronomy 10 (2000), S. 147-156 
    Details
    ISSN: 1572-9508
    Keywords: adaptive optics ; laser guide star ; mesospheric sodium layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this article we investigate the short-term characteristics of the sodium layer and their implications for laser guide star systems. We report measurements of sodium density andcentroid-height variations on timescales of 100 ms upwards. Significant centroid-height variations on short timescales may necessitate frequent refocussing of the beam and wavefront sensor system.We present results from observations of the mesospheric sodium layer taken at the Max Planck observatory in Calar Alto, Spain in September 1997 and August 1998. We describe our experiment which uses the resonant optical backscatter of 589.2 nm laser light from the upper atmosphere as a measure of sodium abundance.Short-term variations are dominated by the formation of dense sporadic layers in the normal sodium layer. Measurements were made on 3 nights in 1997 and on 2 nights in 1998. Somewhat unexpectedly for a mid-latitude site, sporadic sodium layers were seen on 4 of these 5 nights. One of the sporadic layers was observed for its duration. The 2 km wide layer reached a maximum intensity of approximately two and a half times that of the background layer and could be distinguished from the background for over five hours. Centroid height variations of up to 400 m were observed on timescales of 1–2 min. In 1998 we were sensitive to variations of 5% or more in total sodium abundance on timescales of 100 ms upwards. We found no evidencefor variations of this level on these short timescales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008126318786
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    Paper (German National Licenses)
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