度盘对径改正的几何原理

立足子实测，用平面几何的方法讨论了子午环度盘对径改正的几何原理与测量设备，测量数据之间的关系。     

低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和处理方法。为了进一步完善采用组合固定角距法测定对径改正的方法，在第三章，研究了提高对径改正测量精度的方法，重新推导了对径改正的计算公式，并就某些具体的条件，对其进行了模拟验证，得到了较为满意的结果     

测定度盘分划改正的新方法──组合固定角距法

本文分析了国外用于测定度盘分划改正的几种方法，并分析了固定角距法的优点和不足之处；详细叙述了组合固定角距法测定对径改正的原理和计算公式；并且讨论了两对显微镜之间夹角变化以及显微镜比例尺变化对对径改正的影响，给出了相应的修正方法。用固定角距法所测的对径改正精度可达±０″．００９。     

测定度盘对径改正的要求和条件

介绍了低纬子午环的度盘、读数显微镜及其读数系统的配置情况，论述了测定每条对径改正的必要性，并从对径读数中所含的误差，分析了在未对度盘和读数显微镜的装调提出苛刻要求的条件下，如何将度盘对径改正和其他误差影响一道测定出来，对对径读数作修正，以保证度盘读数的高精度。     

低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了 低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和和。     

子午环度盘对径改正测试的研究

评述了各种度盘对径改正的方法；用玫瑰系列法对DCMT进行N=180的抽样实验测试，估计DCMT度盘常规读数对径误差为±0．25"。通过对度盘所有对径测试（N=5400）的精度统计特性的分析，得出49°30'、46°40'、43°12'是最优化的玫瑰系列测试组合；此外还论证了当对精度的统计特性的随机性要求不很严格时，在DCMT上实施小玫瑰角系列是可行的，其最优化组合是0°10'、46°40'、50°24'角系列。     

一种测定氢脉泽腔Qc值和耦合系数β的新方法

本描述一种测量氢脉泽微波谐振腔参数的新方法，在一些测量中，可同时得以谐振腔的有载QL和无载Q0以及耦合系数β。     

InSAR技术现状与应用

合成孔径雷达干涉测量(InSAR)是近期发展起来的一种新型空间对地观测技术。经相干处理，它把合成孔径雷达(SAR)产生的单视复数图像中的相位信息提取出来，给出目标点的三维信息。由于SAR具有全天候、全天时和对某些地物有一定穿透性等特点，使InSAR技术的潜在应用领域相当广泛，目前已经成为地学界相关研究的热点之一。介绍了SAR和InSAR的基本原理与发展概况，分析了InSAR测量模式的测高精度，着重讨论了InSAR技术的应用及其与天文地球动力学研究的相互促进关系。     

The Effect Of Zonal Tides On The DynamicalEllipticity Of The EarthAnd Its Influence On The Nutation

In this paper, the expressions of variations of the dynamical ellipticity and the principal moments of inertia due to the deformations produced by the zonal part of the tidal potential are obtained. Starting from these expressions, we have studied from equations related to Hamiltonian theory, their effects on the nutation and finally we have evaluated numerically such influences, with a level of truncation at 0.1 μas. Thus we have shown that some coefficients are quite large with respect to the usual accuracy of up-to-date observations. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Availability of Phosphorus in The Bacterial Model of The Interstellar Grains

It is shown that phosphorus availability is in close balance with the phosphorus requirement of the bacterial grain model. This correspondence, which would be fortuitous if the interstellar grains were of inorganic origin, points to the correctness of the biological model. This revised version was published online in July 2006 with corrections to the Cover Date.     

The lunar exosphere: The sputtering contribution

We have extended our Monte Carlo model of exospheres [Wurz, P., Lammer, H., 2003. Icarus 164 (1), 1-13] by treating the ion-induced sputtering process from a known surface in a self-consistent way. The comparison of the calculated exospheric densities with experimental data, which are mostly upper limits, shows that all of our calculated densities are within the measurement limits. The total calculated exospheric density at the lunar surface of about 1×¹⁰⁷ m⁻³ as result of solar wind sputtering we find is much less than the experimental total exospheric density of about ¹⁰¹² m⁻³. We conclude that sputtering contributes only a small fraction of the total exosphere, at least close to the surface. Because of the considerably larger scale height of atoms released via sputtering into the exosphere, sputtered atoms start to dominate the exosphere at altitudes exceeding a few 1000 km, with the exception of some light and abundant species released thermally, e.g. H₂, He, CH₄, and OH. Furthermore, for more refractory species such as calcium, our model indicates that sputtering may well be the dominant mechanism responsible for the lunar atmospheric inventory, but observational data does not yet allow firm conclusions to be drawn.     

The Large-Scale Structures Of The Quiet-Sun Photosphere

The area density distribution of bright photospheric points on the quiet solar surface is not uniform. The distributions show some considerable pecularities. This article is a study of their characteristics during the four last solar activity minima in Bartels longitudes. The bright-photospheric-point distributions on the equatorial and polar solar surface exhibit a type of sectoral-hemispherical asymmetry. The density distributions vary a lot, but have the tendency to alternate with a period of 22 years. The phase origin of density concentrations is the first structural pecularity of the photospheric point distributions. The simultaneous appearance of bright regions on the equatorial and polar solar surface in spatial antiphase lock and, at the same time, the half-phase shift (11 years) between polar and equatorial cycles suggests a synchronous distribution process. This time synchronization is the second important pecularity of density concentrations. Therefore, the solar activity organization in minima occurs according to strict synchronization, like being under the control of a very precise clock.     

Primordial Angular Gradients In The Temperature Of The CMBR And The Density Fluctuations

A non-conventional approach is developed and used to find the primordial angular gradient, anisotropy, of the temperature of the Cosmic Microwave Background Radiation (CMBR), as well as the density fluctuations in an adiabatic expanding universe. The obtained results is a consequence of considering the magnitude of the angular gradient of the temperature of the CMBR as a constant function with respect to the proper time of the spatially perturbed FRW expanding universe. This revised version was published online in July 2006 with corrections to the Cover Date.     

On The Origin of The High-Perihelion Scattered Disk: The Role of The Kozai Mechanism And Mean Motion Resonances

We study the transfer process from the scattered disk (SD) to the high-perihelion scattered disk (HPSD) (defined as the population with perihelion distances q > 40 AU and semimajor axes a>50 AU) by means of two different models. One model (Model 1) assumes that SD objects (SDOs) were formed closer to the Sun and driven outwards by resonant coupling with the accreting Neptune during the stage of outward migration (Gomes 2003b, Earth, Moon, Planets 92, 29–42.). The other model (Model 2) considers the observed population of SDOs plus clones that try to compensate for observational discovery bias (Fernández et al. 2004, Icarus , in press). We find that the Kozai mechanism (coupling between the argument of perihelion, eccentricity, and inclination), associated with a mean motion resonance (MMR), is the main responsible for raising both the perihelion distance and the inclination of SDOs. The highest perihelion distance for a body of our samples was found to be q = 69.2 AU. This shows that bodies can be temporarily detached from the planetary region by dynamical interactions with the planets. This phenomenon is temporary since the same coupling of Kozai with a MMR will at some point bring the bodies back to states of lower-q values. However, the dynamical time scale in high-q states may be very long, up to several Gyr. For Model 1, about 10% of the bodies driven away by Neptune get trapped into the HPSD when the resonant coupling Kozai-MMR is disrupted by Neptune’s migration. Therefore, Model 1 also supplies a fossil HPSD, whose bodies remain in non-resonant orbits and thus stable for the age of the solar system, in addition to the HPSD formed by temporary captures of SDOs after the giant planets reached their current orbits. We find that about 12 – 15% of the surviving bodies of our samples are incorporated into the HPSD after about 4 – 5 Gyr, and that a large fraction of the captures occur for up to the 1:8 MMR (a ⋍ 120 AU), although we record captures up to the 1:24 MMR (a ≃ 260 AU). Because of the Kozai mechanism, HPSD objects have on average inclinations about 25°–50°, which are higher than those of the classical Edgeworth–Kuiper (EK) belt or the SD. Our results suggest that Sedna belongs to a dynamically distinct population from the HPSD, possibly being a member of the inner core of the Oort cloud. As regards to 2000 CR₁₀₅ , it is marginally within the region occupied by HPSD objects in the parametric planes (q,a) and (a,i), so it is not ruled out that it might be a member of the HPSD, though it might as well belong to the inner core.     

The Optical Layout Of The HEGRA Cherenkov Telescopes

The raytracing technique was used to derive a suitable design for the HEGRA system of Cherenkov telescopes, which is at present commissioned at La Palma. The reflectors with a diameter of 3.9 m consist of 30 spherical mirrors with focal lengths in the range of 4.88 – 4.94 m. It is shown that 93% of the photons from the Cherenkov light emitted by an extended air shower are contained in the camera pixels, 0.25° in diameter, for the full field of view of = ± 2.5°. The optical performance of the HEGRA design is compared to other layouts.     

The ``Great Debate': The case for AGNs

We summarize the evidence from multiwavelength observations that the dominant power source in the majority of ultraluminous infrared galaxies (ULIGs) may be an active galactic nucleus (AGN). In the broader context of the debate, we also show that –- 1. ULIGs are indeed a key stage in the transformation of merging gas-rich disks into ellipticals,2. ULIGs are plausibly the precursors of quasi-stellar objects (QSOs), and 3. ULIGs do appear to be local templates of the high luminosity tail of major gas-rich mergers at z 1–4.