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L. Zampieri C. Germanà C. Barbieri G. Naletto A. Čadež I. Capraro A. Di Paola C. Facchinetti T. Occhipinti D. Ponikvar E. Verroi P. Zoccarato 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We are developing fast photon-counter instruments to study the rapid variability of astrophysical sources by time tagging photon arrival times with unprecedented accuracy, making use of a Rubidium clock and GPS receiver. The first realization of such optical photon-counters, dubbed AquEYE (the Asiago Quantum Eye), was mounted in 2008 at the 182 cm Copernicus Observatory in Asiago. AquEYE observed the Crab pulsar several times and collected data of extraordinary quality that allowed us to perform accurate optical timing of the Crab pulsar and to study the pulse shape stability on a timescale from days to years with an excellent definition. Our results reinforce the evidence for decadal stability of the inclination angle between the spin and magnetic axis of the Crab pulsar. Future realizations of our instrument will make use of the Galileo Global Navigation Satellite System (GNSS) time signal. 相似文献
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Ignazio Ciufolini Antonio Paolozzi Erricos C. Pavlis John C. Ries Rolf Koenig Richard A. Matzner Giampiero Sindoni Hans Neumayer 《Space Science Reviews》2009,148(1-4):71-104
During the past century Einstein’s theory of General Relativity gave rise to an experimental triumph; however, there are still aspects of this theory to be measured or more accurately tested. Today one of the main challenges in experimental gravitation, together with the direct detection of gravitational waves, is the accurate measurement of the gravitomagnetic field generated by the angular momentum of a body. Here, after a brief introduction on frame-dragging, gravitomagnetism and Lunar Laser Ranging tests, we describe the past measurements of frame-dragging by the Earth spin using the satellites LAGEOS, LAGEOS 2 and the Earth’s gravity models obtained by the GRACE project. We demonstrate that these measurements have an accuracy of approximately 10%. We then describe the LARES experiment to be launched in 2010 by the Italian Space Agency for a measurement of frame-dragging with an accuracy of a few percent. We finally demonstrate that a number of claims by a single individual, that the error budget of the frame-dragging measurements with LAGEOS-LAGEOS 2 and LARES has been underestimated, are indeed ill-founded. 相似文献
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Andrea Tomaello Cristian Bonato Vania Da Deppo Giampiero Naletto Paolo Villoresi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Optical quantum communication exploiting satellites is the most promising field to enable global quantum communication. 相似文献
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G. Noci J.L. Kohl E. Antonucci G. Tondello M.C.E. Huber S. Fineschi L.D. Gardner G. Naletto P. Nicolosi J.C. Raymond M. Romoli D. Spadaro O.H.W. Siegmund C. Benna A. Ciaravella S. Giordano J. Michels A. Modigliani A. Panasyuk C. Pernechele G. Poletto P.L. Smith L. Strachan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(12):2219-2230
We present here the first results obtained by the Ultraviolet Coronagraph Spectrometer (UVCS) operating on board the SOHO satellite. The UVCS started to observe the extended corona at the end of January 1996; it routinely obtains coronal spectra in the 1145 Å – 1287 Å, 984 Å – 1080 Å ranges, and intensity data in the visible continuum. Through the composition of slit images it also produces monocromatic images of the extended corona. The performance of the instrument is excellent and the data obtained up to now are of great interest. We briefly describe preliminary results concerning polar coronal holes, streamers and a coronal mass ejection, in particular: the very large r.m.s. velocities of ions in polar holes (hundreds km/sec for OVI and MgX); the puzzling difference between the HI Ly- image and that in the OVI resonance doublet, for most streamers; the different signatures of the core and external layers of the streamers in the width of the ion lines and in the OVI doublet ratio, indicating larger line-of-sight (l.o.s.) and outflow velocities in the latter. 相似文献
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