南山站对陆地—5号资源卫星的可观测范围及以该站为中心的覆盖区域

本文简要介绍了陆地系列地球资源卫星的轨道特征，并以陆地—５号资源卫星为例，根据南山站的座标计算出该站对陆地—５号资源卫星的可观测范围及以该站为中心的卫星的覆盖区域。     

The nature of Europa's dark non-ice surface material: Spatially-resolved high spectral resolution spectroscopy from the Keck telescope

We present new 1.45-1.75 μm spectra of Europa's dark non-ice material with a spectral resolution (λ/δλ) of 1200, obtained by using adaptive optics on the Keck telescope to spatially separate the spectrum of the non-ice material from that of the surrounding ice-rich regions. Despite the great increase in spectral resolution over the previous best spectra of the non-ice material, taken with Galileo's near-infrared mapping spectrometer (NIMS) with λ/δλ=66, no new fine-scale spectral structure is revealed. The smoothness of the spectra is inconsistent with available laboratory spectra of crystalline hydrated salts at Europa temperatures, but is more consistent with various combinations of non-crystalline hydrated salts and/or hydrated sulfuric acid, as have been matched to the lower-resolution NIMS spectra.     

The spectral variability of Triton from 1997-2000

We present the results of a three-year observational program of long-slit spectroscopy and UBVRI photometry of Triton. We find evidence for short-lived albedo variations at wavelengths less than 0.5 μm with the most notable reddening event measured in October 1997 and “normal” colors returning by May 1998. We report a possible variation in the relative 0.73/0.89 μm methane absorption band strengths, suggesting that the transport or denudation of this species may play a major role in the reddening events.     

Observations with the Visual and Infrared Mapping Spectrometer (VIMS) during Cassini's flyby of Jupiter

The Cassini Visual and Infrared Mapping Spectrometer (VIMS) is an imaging spectrometer covering the wavelength range 0.3-5.2 μm in 352 spectral channels, with a nominal instantaneous field of view of 0.5 mrad. The Cassini flyby of Jupiter represented a unique opportunity to accomplish two important goals: scientific observations of the jovian system and functional tests of the VIMS instrument under conditions similar to those expected to obtain during Cassini's 4-year tour of the saturnian system. Results acquired over a complete range of visual to near-infrared wavelengths from 0.3 to 5.2 μm are presented. First detections include methane fluorescence on Jupiter, a surprisingly high opposition surge on Europa, the first visual-near-IR spectra of Himalia and Jupiter's optically-thin ring system, and the first near-infrared observations of the rings over an extensive range of phase angles (0-120°). Similarities in the center-to-limb profiles of H⁺₃ and CH₄ emissions indicate that the H⁺₃ ionospheric density is solar-controlled outside of the auroral regions. The existence of jovian NH₃ absorption at 0.93 μm is confirmed. Himalia has a slightly reddish spectrum, an apparent absorption near 3 μm, and a geometric albedo of 0.06±0.01 at 2.2 μm (assuming an 85-km radius). If the 3-μm feature in Himalia's spectrum is eventually confirmed, it would be suggestive of the presence of water in some form, either free, bound, or incorporated in layer-lattice silicates. Finally, a mean ring-particle radius of 10 μm is found to be consistent with Mie-scattering models fit to VIMS near-infrared observations acquired over 0-120° phase angle.     

Fresnel modeling of hematite crystal surfaces and application to martian hematite spherules

The gray crystalline hematite at Meridiani Planum first discovered by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) instrument occurs as spherules that have been interpreted as concretions. Analysis of the TES and mini-TES spectra shows that no 390 cm⁻¹ feature is present in the characteristic martian hematite spectrum. Here, we incorporate the mid-IR optical constants of hematite into a simple Fresnel reflectance model to understand the effect of emission angle and crystal morphology on the presence or absence of the 390 cm⁻¹ feature in an IR hematite spectrum. Based on the results we offer two models for the internal structure of the martian hematite spherules.     

LonGSp: A near infra-red spectrometer

We present a new cooled grating near infra-red spectrometer designed to acquire spectra at the TIRGO telescope in the 0.9÷2.5m region with a resolving power of 300÷4000, equipped with a Rockwell NICMOS 3 detector.     

Neutron irradiation and post-irradiation annealing of rutile (TiO2−x ): effect on hydrogen incorporation and optical absorption

Neutron irradiation and post-irradiation annealing under oxidising and reducing conditions have been used to investigate H incorporation in, and the optical properties of, reduced (TiO_2−x ) rutile. Optical absorption in rutile is mainly due to a Ti³⁺ Ti⁴⁺ intervalence charge transfer effect. The main mechanism for H incorporation in rutile involves interstitial H not coupled to other defects, which has important implications for the rate of H diffusion, and possibly also on the electrical properties of rutile. Additional minor OH absorption bands in IR spectra indicate that a small amount of interstitial H is coupled to defects such as Ti³⁺ on the main octahedral site, and indicates that more than one H incorporation mechanism may operate. Concentration of oxygen vacancies has a controlling influence on the H affinity of rutile.     

基于EOS/MODIS资料的沙尘遥感监测模型研究

在EOS MODIS资料可见光波段光谱特性的深入分析的基础上，提出了一种完全用MODIS可见光波段监测沙尘信息的技术方法。充分利用MODIS资料可见光范围波段划分细致的特点，构造了不同的光谱特征判别函数作为决策树的分支，最后用决策树法成功地对几次沙尘暴过程进行了沙尘信息遥感监测。结果表明，该方法具有良好的效果和实用性。     

Incorporation of Cr<Superscript>3+</Superscript> in dickite: a spectroscopic study

 We have investigated a well-ordered sample of natural Cr-bearing dickite from Nowa Ruda (Lower Silesia, Poland) using electron paramagnetic resonance (EPR) at X- and Q-band frequencies (9.42 and 33.97 GHz, respectively) and optical diffuse reflectance spectroscopy. The observation of the spin-forbidden transitions at 15500 and 14690 cm⁻¹ allows us to unambiguously identify the major contribution of octahedrally coordinated Cr³⁺ ions in the optical spectrum. The X- and Q-band EPR spectra show two superposed Cr³⁺ signals. The corresponding fine-structure parameters were determined at room temperature and 145 K. These results suggest the substitution of Cr³⁺ for Al³⁺ in equal proportions in the two unequivalent octahedral sites of the dickite structure. In kaolin group minerals, the distortion around Cr³⁺ ions (λ≈ 0.2–0.4) in Al sites is significantly less rhombic than that observed around Fe³⁺ ions (λ≈ 0.6–0.8). Received: 29 June 2001 / Accepted: 22 October 2001