Extinction and Sky Brightness at Two Solar Observatories     

M.J. Penn  H. Lin  A.M. Schmidt  J. Gerke  F. Hill 《Solar physics》2004,220(1):107-120

The Advanced Technology Solar Telescope site survey Sky Brightness Monitor simultaneously images the solar disk and the sky to about 8 solar radii in four wavelengths at 450, 530, 890 and 940 nm. One day of data from Mees Solar Observatory on Haleakala and from the National Solar Observatory at Sacramento Peak (Sunspot, New Mexico) are analyzed. Both sites show strong Rayleigh extinction, but while Haleakala shows a larger aerosol component, Sunspot shows a large variation in the aerosol component. Overall the Haleakala extinction varies as ^–2 whereas the Sunspot extinction changes from about ^–3.5 to about ^–2, suggesting an increasing aerosol component during the day. Water vapor absorption measurements from both sites are similar, though Sunspot shows larger time variations than Haleakala. The instrument-corrected sky brightness from both sites show comparable values, and again the Sunspot data show more variations. The sky brightness values show a radial dependence of sky brightness of r ^–0.1 at Haleakala, but a dependence of r ^–1.0 at Sunspot. The wavelength variation of the sky brightness at Haleakala is relatively constant at ^–1.5 but varies at Sunspot from ^–1.5 to ^–0.1 again suggesting an increasing aerosol contribution during the day at Sunspot. Finally, dust measurements near the ground are compared with the extinction wavelength exponent for data taken at Haleakala on 24 Feb. 2003. The measurements suggest more large dust particles are present near the ground than averaged over the whole air column.  相似文献   

Benchmarks for validating range-dependent seismo-acousticpropagation codes     

Joo Thiam Goh Schmidt  H. Gerstoft  P. Woojae Seone 《Oceanic Engineering, IEEE Journal of》1997,22(2):226-236

The availability of fast and relatively low-cost computing power has resulted in radical changes to the role of seismo-acoustic modeling. With the increase in the number of models available, there is the inevitable question of how can one go about validating all these numerical schemes. Recently, the issue of establishing reference solutions for range dependent ocean acoustic problems was addressed within the Acoustical Society of America. This has resulted in a set of well-defined benchmarks for range-dependent fluid problems. However, to date, there is no consistent set of benchmarks for the range-dependent seismo-acoustic codes. In this paper, we present a collection of problems intended for general use by the modeling community for validation of new computational schemes. A number of new seismo-acoustic codes are applied to produce reference solutions for these benchmarks  相似文献   

Pre- and post-folding magnetizations from the early Devonian Snowy River Volcanics and Buchan Caves Limestone, Victoria     

P. W. Schmidt  B. J. J. Embleton  H. C. Palmer 《Geophysical Journal International》1987,91(1):155-170

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Chandra temperature and metallicity maps of the Perseus cluster core     

R. W. Schmidt  A. C. Fabian  J. S. Sanders 《Monthly notices of the Royal Astronomical Society》2002,337(1):71-78

We present temperature and metallicity maps of the Perseus cluster core obtained with the Chandra X-ray Observatory. We find an overall temperature rise from  ∼3.0 keV  in the core to  ∼5.5 keV  at 120 kpc and a metallicity profile that rises slowly from  ∼0.5  solar to  ∼0.6  solar inside 60 kpc, but drops to  ∼0.4  solar at 120 kpc. Spatially resolved spectroscopy in small cells shows that the temperature distribution in the Perseus cluster is not symmetrical. There is a wealth of structure in the temperature map on scales of  ∼10  arcsec (5.2 kpc) showingswirliness and a temperature rise that coincides with a sudden surface brightness drop in the X-ray image. We obtain a metallicity map of the Perseus cluster core and find that the spectra extracted from the two central X-ray holes as well as the western X-ray hole are best-fit by gas with higher temperature and higher metallicity than is found in the surroundings of the holes. A spectral deprojection analysis suggests, however, that this is due to a projection effect; for the northern X-ray hole we find tight limits on the presence of an isothermal component in the X-ray hole, ruling out volume-filling X-ray gas with temperatures below 11 keV at 3σ.  相似文献   

Phase Resolved High Speed Photometry and Spectroscopy of Pulsars     

Claudio Cumani  Karl-Heinz Mantel 《Experimental Astronomy》2001,11(2):145-150

We describe the implementation of two High Time Resolution modes for ESO's new generation CCD controller FIERA. These new modes have been used to perform phase-resolved high speed photometry and spectroscopy of pulsars with the FORS instruments at the VLT.  相似文献   

Ein Chemisches Modell Fur Den Aufund Abbau Organischen Materials Und Dessen Anwendung in Der Offenen See     

Szekielda  Karl-Heinz 《ICES Journal of Marine Science》1968,32(2):180-187

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Absolute spectrophotometry of Comet Kohoutek 1973f: I. Column densities of cyanogen     

J.S. Neff  D. Ketelsen  G.D. Schmidt  J.B. Tatum 《Icarus》1976,27(4):545-551

Absolute spectrophotometry of the coma of Comet Kohoutek 1973f is discussed for the nights of January 24 and 26, 1974. Specific intensities are measured for spectral features and a continuum band in the wavelength region λλ3460–6062Å. The (0, 0) band of the Δν = 0 sequence of the violet system of the cyanogen molecule is analyzed and column densities of 1.7 × 10¹⁵m^?2 and 3.4 × 10¹⁴m^?2 are found for January 24 and 26, 1974, respectively. The analysis of the bands of C₂ will be reported in a second paper of this series.  相似文献   

The response of palaeomagnetic data to Earth expansion     

P. W. Schmidt  D. A. Clark 《Geophysical Journal International》1980,61(1):95-100

Summary. Attempts to estimate palaeo-radii of the Earth, using palaeomagnetic data have necessarily been based on simplistic Earth models. It has been asserted that real geological processes are too complex to enable us to approach the problem quantitatively, and such attempts yield invalid results. We examine this and argue that, to the contrary, it appears that errors introduced by allowing for more realistic behaviour of the continents, e.g. 'orange-peel effect' and crustal extension, are smaller by an order of magnitude than the response of palaeomagnetic data to simplified expansion models.
From a qualitative argument, it is shown that the observed Late Palaeozoic and Early Mesozoic palaeomagnetic data are not what should be expected from an expanded Earth. We conclude that it appears unlikely that the Earth has expanded significantly since the Early Mesozoic.  相似文献   

Satellite investigations on the fluctuations of the subtropical and antarctic convergence zones     

Dr. Karl-Heinz Szekielda 《Ocean Dynamics》1983,36(1):25-43

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SMART-1 after lunar capture: First results and perspectives   总被引：1，自引：0，他引：1  

B. H. Foing  G. D. Racca  A. Marini  E. Evrard  L. Stagnaro  M. Almeida  D. Koschny  D. Frew  J. Zender  D. Heather  M. Grande  J. Huovelin  H. U. Keller  A. Nathues  J. L. Josset  A. Malkki  W. Schmidt  G. Noci  R. Birkl  L. Iess  Z. Sodnik  P. McManamon 《Journal of Earth System Science》2005,114(6):689-697

SMART-1 is a technology demonstration mission for deep space solar electrical propulsion and technologies for the future. SMART-1 is Europe’s first lunar mission and will contribute to developing an international program of lunar exploration. The spacecraft was launched on 27th September 2003, as an auxiliary passenger to GTO on Ariane 5, to reach the Moon after a 15-month cruise, with lunar capture on 15th November 2004, just a week before the International Lunar Conference in Udaipur. SMART-1 carries seven experiments, including three remote sensing instruments used during the mission’s nominal six months and one year extension in lunar science orbit. These instruments will contribute to key planetary scientific questions, related to theories of lunar origin and evolution, the global and local crustal composition, the search for cold traps at the lunar poles and the mapping of potential lunar resources  相似文献