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111.
We describe the integral field unit (IFU) which converts the Gemini Multiobject Spectrograph (GMOS) installed on the Gemini-North telescope to an integral field spectrograph,which produces spectra over a contiguous field of view of 7 × 5 arcsec with spatial sampling of 0.2 arcsecover the wavelength range 0.4-1.0 μm.GMOS is converted to this mode by the remote insertion of the IFU into thebeam in place of the masks used for the multiobject mode. A separate fieldof half the area of the main field, but otherwise identical, is alsoprovided to improve background subtraction. The IFU contains 1500lenslet-coupled fibres and was the first facility of any type for integralfield spectroscopy employed on an 8/10 m telescope.We describe the design, construction and testing of the GMOS IFU and present measurements of the throughput both in the laboratory and at the telescope. We compare these with a theoretical prediction made before construction started. All are in good agreement with each other, with the on-telescope throughput exceeding 60% (averaged over wavelength). Finallywe show an example of data obtained during commissioning to illustrate the power of the device.  相似文献   
112.
Orbital parameters of the satellite NIMBUS 1 ROCKET (1964-52B) have been determined at 285 epochs using about 14,500 optical and radar observations during the last 2233 days of its life. 1964-52B was in an orbit inclined at about 98.7° to the Equator and it decayed on 13 August 1974. The orbital elements were found using the RAE orbit refinement program PROP 6 giving average orbital accuracies in perigee height and inclination at 110 m and 0.002° respectively.  相似文献   
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A new updated version of the MSK macroseismic intensity scale has been prepared by a Working Group of the European Seismological Commission and has been published in April 1993 (European Macroseismic Scale 1992: updated MSK scale, 1993, ed. by G. Grünthal, Cahiers du Centre Européen de Geodynamique et de Séismologie, no. 7).  相似文献   
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A complex of channels underlying the Baginton-Lillington Gravel (Baginton Formation) at Waverley Wood Quarry, Warwickshire is described. Fossil pollen and plant macrofossils, Coleoptera, Ostracoda, Mollusca and Mammalia are described from the channel-fill deposits. Consideration of all the evidence allows the identification of four separate stages of channel fill which largely occurred under a cool temperate climate. At the top of Channel 2 evidence for a cold, continental climatic episode can be recognised, suggesting that the whole complex was deposited under a fluctuating climate at the end of a temperate stage. At two levels in the channels human artefacts were recovered confirming the presence of Palaeolithic people in Warwickshire during the deposition of the sediments. Amino-acid geochronology suggests an age within the ‘Cromerian Complex’ Stage for the channels. The small vertebrate and molluscan faunas indicate that the deposits are no older than the latter part of the ‘Cromerian Complex’ Stage of East Anglia. The regional stratigraphic significance of the Waverley Wood succession is outlined.  相似文献   
116.
In the context of the survival of periodic comets of different origins, rotational breakup and tidal disruption could be important, especially of the short period comets injected from the Kuiper belt. This is because long-period comets from the distant Oort cloud tend to be subject to thermal stress and volatile 'explosion' far more severely. A simple calculation using the Öpik method of random planetary close encounters was performed to estimate the probability of tidal disruption of comets and scattered Kuiper belt objects (SKBOs) during their orbital migration. It was found that a large fraction of the short period comets and SKBOs might have been internally fragmented by single or multiple close encounters with the outer planets.  相似文献   
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In this paper we show that a change in the signs of some of the metric components of the solution of the field equations for the classical cosmic string results in a solution which we interpret as a time-dependent wall composed of tachyons. We show that the walls have the property of focusing the paths of particles which pass through them. As an illustration of this focusing, we demonstrate the results of a simple simulation of the interaction between one such tachyon wall and a rotating disk of point masses. This interaction leads to the temporary formation of spiral structures. These spiral structures exist for a time on the order of one galactic rotation. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
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