多功能天文经纬仪图像采集系统

多功能天文经纬仪是云南天文台新近研制的一种基于通用CCD观测的天体测量望远镜。在这台新型望远镜中,用两个模拟相机分别测量仪器的水平差和高度轴的准直差。当望远镜工作时,望远镜控制系统发出两路触发信号．一路控制数字相机,另一路控制两个模拟相机。两个采集卡分别安装在不同的工作站上,工作在外触发模式。介绍了望远镜的转轴观测模式,主要包含转轴前和转轴后两个观测阶段,采集图像的时刻和数量是由外触发信号控制的。介绍了硬件结构图。说明了软件编写的流程和实现方法．并且对系统中涉及的主要程序算法进行了较为详细的说明。图像采集软件的编写采用VC＋＋和SaperaLT。给出了采集系统软件的工作界面及图像采集系统采集的图像．并对数字相机拍摄的恒星像进行了简单的分析。     

云南天文台40米射电望远镜S波段总流量观测系统研制和测试

为提高云南天文台40 m射电望远镜射电源流量观测性能,针对S波段现有问题,设计并研制了一套流量观测系统.研发硬件包括抗干扰射频模块、K因子辐射计.同时开发了与新系统配合工作的观测软件,用于数据采集、实时显示、储存及处理.系统研制完成后,进行了安装测试.测试方式为河外致密源ON/OFF流量观测.观测结果表明,实测灵敏度接近理论值水平,新研制系统性能较旧设备有显著提高.     

IRAF软件在Blazars天体中的CCD测光自动数据处理研究

针对IRAF软件在绝对测光法观测Blazars天体CCD测光中的应用,开发了一套自动数据处理的程序.该程序可以减少人为误操作的干扰,使观测结果更为稳定,提高了数据处理的效率.同时,在长期研究和使用IRAF软件的基础上,给出了我们应用IRAF软件在CCD测光中的一些研究结果,并对在Redhat Linux中的自动测光过程进行了总结.     

丽江2.4米望远镜多波段测光观测控制系统的设计与开发

丽江2.4 m望远镜在卡塞格林焦点上安装多个观测设备,为了最大限度地提高望远镜的观测效率,需要实现对各终端控制系统的集成控制。原有的多波段测光系统的控制程序不具备集成化的条件,需要对其进行集成化开发以满足要求。借鉴云南暗弱天体光谱成像仪和望远镜的控制系统,在Linux系统下对多波段测光系统的控制系统进行重新开发,设计并完成了3个主要部分:观测控制程序、设备控制程序和设备数据库,成功实现了多波段测光系统、云南暗弱天体光谱成像仪与望远镜统一的控制模式,使其具备与其它设备控制系统集成的能力,满足多终端集成控制的要求。     

FAST望远镜40米模型天文观测软件的开发

针对FAST的天文观测要求,对其天文观测软件进行了设计与开发。首先介绍了FAST天文观测的原理,对天文观测软件进行了需求分析。而后提出了馈源天文运动轨迹规划算法,并进行了仿真。针对其轨迹要求给出了控制方法,对天文观测控制软件进行了设计与实现。最后通过现场实地实验,验证了本文所提的算法与软件的可行性。     

基于ZeroMQ的观测控制系统底层通信架构分析与测试

观测控制系统是当前的一个研究热点,底层通信是观测控制系统架构的一个重要环节。但传统的观测控制系统一般采用裸套接技术实现,缺少统一的传输控制机制,在密集数据通信时经常存在延迟,影响实时控制的需要;同时缺少广播与组播机制,限制了观测控制系统的设计。针对观测控制系统的要求,研究了基于ZeroMQ不同通信模型及对应的天文控制模式,分析了不同的通信控制架构的可用性,在此基础上通过实验对相应的通信模型进行测试,验证其在天文仪器分布控制中的可用性。测试结果进一步说明,ZeroMQ构建观测控制系统的底层通信架构是可行的,能够满足观测控制系统对设备的各种控制需求。     

基于Blender的天文数据三维可视化

天文学是一门以观测为基础的古老学科,在不同波段的各种形式天文望远镜的观测已经积累了大量的数据,天文学领域对数据的处理与展示有着很高的要求与期望。目前有很多团队着力于开发天文数据的可视化分析工具和软件,同时,有很多其他领域的软件,通过整合和修改也可以应用到天文数据上。介绍了对三维建模软件Blender的工具包的再开发,结合其内置的Python API和BPY库,实现对常用天文数据三维数据单元(Data Cube)和N体模拟结果的实时静态和动态三维可视化。     

基于ASCOM标准的天文电动调焦器设计

随着天文技术的不断发展,远程观测和自主观测逐渐成为天文观测的主流趋势,自动调焦技术也越来越受到重视。电动调焦器是天文望远镜不可或缺的附属设备,是实现自动调焦的关键设备。为实现云南天文台丽江观测站10英寸米德望远镜的自动调焦,自行研发了一套天文电动调焦器,设计相关控制电路,制定串口通信协议,并编写了一套开源天文公共对象模型(Astronomy Common Object Model,ASCOM)驱动程序SS Focuser,详细介绍了该电动调焦器的结构原理和实现方法,实测结果表明,电动调焦器具有很好的稳定性,完全满足设计要求,为天文电动调焦器设计提供了可借鉴的经验和方法。     

人卫激光测距资料的屏幕预处理方法

本针对人卫激光测距中白天观测的高噪声环境，提出并实现了计算机屏幕显示观测数据，并直接对资料进行屏幕处理的软件。本介绍了它的设计思想，具有的功能和实际应用情况。本方法为资料的预处理提供了新的路径，它具有处理崩溃点ε达90％以上的极高噪声能力。本方法还可以应用在噪声数大的其它天观测等实测工作中。     

平均风作用对天马望远镜面形精度和指指向精度的影响

天马望远镜的最高工作频段为43 GHz。为保证高质量的观测结果,需要研究风载荷对天线精度的影响。首先对观测站实测的风速风向数据做了统计分析,结果显示:10 m高度处10min时距平均风速小于4 m·s~(-1)的占比超过80%,主导风向为北-西北方向。然后,通过将倾斜仪实测结果与有限元模拟结果进行对比,验证了模拟的有效性,并进一步分析了在不同迎风姿态、不同风速下天线结构的平均风荷载响应,以及天线面形精度和指向精度的变化。结果表明,平均风荷载对天线指向精度,尤其是俯仰角指向精度的影响较大,对面形精度的影响较小;在弹性范围内,天线面形精度和指向精度与风速间均为二次关系。研究结果可为天线面形精度和指向精度的评估提供参考。     

LAMOST观测控制系统体系结构设计

由于大天区面积多目标光纤光谱天文望远镜(LAMOST)系统非常复杂,系统研制的时间比较长,系统建成后有相当长的使用年限,就要求观测控制系统(OCS)有足够长的生命周期(使用、维护及升级),可扩展性和良好的可维护性,因此系统需要一个合理健全、内在一致的体系结构。根据OCS的建模和体系结构的概念,在对OCS建模及参考各种体系结构模式的基础上完成了基于构件的层状的OCS系统体系构架,融合了MVC,代理等体系结构模式。详细讨论了OCS体系结构的静态模型和动态模型,并在OCS的1级系统实现了此体系结构。     

Observations of OCS and a search for OC3S in the interstellar medium

Observations of OCS and a search for OC3S are reported, with particular reference to cold dust clouds. OCS has been detected for the first time in dark clouds with a mean fractional abundance relative to hydrogen of approximately 3 x 10(-9); this is approximately 4 times greater than that observed for giant molecular clouds. This results is discussed in the context of molecule formation mechanisms. Observations of the J = 1 --> 0 transition of OCS indicate that this transition is amplifying the background continuum radiation in the direction of Sgr B2.     

System for scientific payload information support for the <Emphasis Type="Italic">Phobos-Grunt</Emphasis> project

This article describes a device called the System for Scientific Payload Information Support (SSPIS) that controls the traffic (commands, board time code, science and telemetry data) between the onboard computer system (OCS) and the scientific instrumentation (SI) of the spacecraft (SC) of the Phobos-Grunt project. The functional scheme of the device and the functions of the included modules are described. The scope of the testing of the device is considered. The software developed to perform functional testing of the hardware resources of the device is described.     

LAMOST CCD相机总控的设计与实现

大天区面积多目标光纤光谱望远镜(LAMOST)使用了16台低色散光谱仪、32台科学级CCD相机对目标进行光谱拍摄。CCD集总控制器MASTER是其32台CCD相机的中枢,它控制CCD按观测需要进行曝光、管理CCD状态和诊断相机故障。针对LAMOST相机系统的结构和UCAM控制器的特点,设计了MASTER系统;介绍了与OCS和UCAM接口的方式,并分析了对命令和状态的管理。     

Spatially-resolved high-resolution spectroscopy of Venus 2. Variations of HDO, OCS, and SO2 at the cloud tops

While CO, HCl, and HF, that were considered in the first part of this work, have distinct absorption lines in high-resolution spectra and were detected four decades ago, the lines of HDO, OCS, and SO₂ are either very weak or blended by the telluric lines and have not been observed previously by ground-based infrared spectroscopy at the Venus cloud tops. The H₂O abundance above the Venus clouds is typically below the detection limit of ground-based IR spectroscopy. However, the large D/H ratio on Venus facilitates observations of HDO. Converted to H₂O with D/H ≈ 200, our observations at 2722 cm⁻¹ in the Venus afternoon show a H₂O mixing ratio of ∼1.2 ppm at latitudes between ±40° increasing to ±60° by a factor of 2. The observations in the early morning reveal the H₂O mixing ratio that is almost constant at 2.9 ppm within latitudes of ±75°. The measured H₂O mixing ratios refer to 74 km. The observed increase in H₂O is explained by the lack of photochemical production of sulfuric acid in the night time. The recent observations at the P-branch of OCS at 4094 cm⁻¹ confirm our detection of OCS. Four distributions of OCS along the disk of Venus at various latitudes and local times have been retrieved. Both regular and irregular components are present in the variations of OCS. The observed OCS mixing ratio at 65 km varies from ∼0.3 to 9 ppb with the mean value of ∼3 ppb. The OCS scale height is retrieved from the observed limb darkening and varies from 1 to 4 km with a mean value of half the atmospheric scale height. SO₂ at the cloud tops has been detected for the first time by means of ground-based infrared spectroscopy. The SO₂ lines look irregular in the observed spectra at 2476 cm⁻¹. The SO₂ abundances are retrieved by fitting by synthetic spectra, and two methods have been applied to determine uncertainties and detection limits in this fitting. The retrieved mean SO₂ mixing ratio of 350 ± 50 ppb at 72 km favors a significant increase in SO₂ above the clouds since the period of 1980-1995 that was observed by the SOIR occultations at Venus Express. Scale heights of OCS and SO₂ may be similar, and the SO₂/OCS ratio is ∼500 and may be rather stable at 65-70 km under varying conditions on Venus.     

Formation of Carbonyl Sulfide (OCS) from Carbon Monoxide and Sulfur Vapor and Applications to Venus

We use gas chromatography to identify and measure the amounts of carbonyl sulfide (OCS) formed in a gas-flow system via the net thermochemical reactionsat temperatures of 470–612°C and ambient atmospheric pressure. The goal of our work is to evaluate the importance of reactions (1) to (3), which have been proposed as potential sources of OCS in Venus' lower atmosphere. Our results show OCS formation by reaction (3), but not by reactions (1) or (2) under our experimental conditions. Based on our results, experimental data from the literature, and theoretical models in the literature, we conclude that (1) the reaction of S₂and CO is an important source of OCS in Venus' lower atmosphere, and (2) probably neither reaction (1) nor reaction (2) is an important source of OCS on Venus. Finally, we use thermodynamic data for reaction (3) and Venera spacecraft observations of CO and sulfur vapor at 0–12-km altitude to calculate an OCS equilibrium abundance of 1–14 ppmv, with a nominal value of 5 ppmv, for reaction (3) near Venus' surface.     

Time dependent chemical study of contracting interstellar clouds. II. abundances of oxygen- and sulphur-bearing molecules

Abstract. We have constructed a chemical reaction system in a contracting interstellar cloud. In paper (I) we have presented the details of the physical and chemical scheme and the method of solution. The results of our chemical model produce fractional abundances of H₂CO, CO, OH, H₂O, SO and OCS which are in good agreement with the results of observations. On the other hand, the results of chlorine-bearing species are not in agreement with those of the observations. The calculated abundances of H₂CO, CO, OH, H₂O, SO, OCS and Cl⁺ are in agreement with the results of previous theoretical studies.     

LAMOST观测控制系统用户界面设计

位于国家天文台兴隆观测基地的大天区面积多目标光纤光谱天文望远镜(LAMOST)是世界上最大的、可操控的反射施密特望远镜。为了便于控制望远镜,提高观测效率,设计了观测控制系统图形用户界面。首先分析了LAMOST望远镜的控制软件体系结构,采用基于场景的以用户为中心的设计方法,对界面进行了分析和设计。使用Qt、CORBA、多线程技术和MVC模式,实现了用户界面,并对界面进行了测试。最后,用户界面得到了用户的认可,成功应用于LAMOST观测。     

Chemical kinetic model for the lower atmosphere of Venus

A self-consistent chemical kinetic model of the Venus atmosphere at 0-47 km has been calculated for the first time. The model involves 82 reactions of 26 species. Chemical processes in the atmosphere below the clouds are initiated by photochemical products from the middle atmosphere (H₂SO₄, CO, S_x), thermochemistry in the lowest 10 km, and photolysis of S₃. The sulfur bonds in OCS and S_x are weaker than the bonds of other elements in the basic atmospheric species on Venus; therefore the chemistry is mostly sulfur-driven. Sulfur chemistry activates some H and Cl atoms and radicals, though their effect on the chemical composition is weak. The lack of kinetic data for many reactions presents a problem that has been solved using some similar reactions and thermodynamic calculations of inverse processes. Column rates of some reactions in the lower atmosphere exceed the highest rates in the middle atmosphere by two orders of magnitude. However, many reactions are balanced by the inverse processes, and their net rates are comparable to those in the middle atmosphere. The calculated profile of CO is in excellent agreement with the Pioneer Venus and Venera 12 gas chromatographic measurements and slightly above the values from the nightside spectroscopy at 2.3 μm. The OCS profile also agrees with the nightside spectroscopy which is the only source of data for this species. The abundance and vertical profile of gaseous H₂SO₄ are similar to those observed by the Mariner 10 and Magellan radio occultations and ground-based microwave telescopes. While the calculated mean S₃ abundance agrees with the Venera 11-14 observations, a steep decrease in S₃ from the surface to 20 km is not expected from the observations. The ClSO₂ and SO₂Cl₂ mixing ratios are ∼10⁻¹¹ in the lowest scale height. The existing concept of the atmospheric sulfur cycles is incompatible with the observations of the OCS profile. A scheme suggested in the current work involves the basic photochemical cycle, that transforms CO₂ and SO₂ into SO₃, CO, and S_x, and a minor photochemical cycle which forms CO and S_x from OCS. The net effect of thermochemistry in the lowest 10 km is formation of OCS from CO and S_x. Chemistry at 30-40 km removes the downward flux of SO₃ and the upward flux of OCS and increases the downward fluxes of CO and S_x. The geological cycle of sulfur remains unchanged.     

High-resolution spectroscopy of Venus: Detection of OCS, upper limit to H2S, and latitudinal variations of CO and HF in the upper cloud layer

Venus was observed at 2.4 and 3.7 μm with a resolving power of 4×¹⁰⁴ using the long-slit high-resolution spectrograph CSHELL at NASA IRTF. The observations were made along a chord that covered a latitude range of ± 60° at a local time near 8:00. The continuous reflectivity and limb brightening at 2.4 μm are fitted by the clouds with a single scattering albedo 1−a=0.01 and a pure absorbing layer with τ=0.09 above the clouds. The value of 1−a agrees with the refractive index of H₂SO₄ (85%) and the particle radius of 1 μm. The absorbing layer is similar to that observed by the UV spectrometer at the Pioneer Venus orbiter. However, its nature is puzzling. CO₂ was measured using its R32 and R34 lines. The retrieved product of the CO₂ abundance and airmass is constant at 1.9 km-atm along the instrument slit in the latitude range of ± 60°. The CO mixing ratio (measured using the P21 line) is rather constant at 70 ppm, and its variations of ∼10% may be caused by atmospheric dynamics. The observed value is higher than the 50 ppm retrieved previously from a spectrum of the full disk, possibly, because of some downward extension of the mesospheric morningside bulge of CO. The observations of the HF R3 line reveal a constant HF mixing ratio of 3.5±0.5 ppb within ± 60° of latitude, which is within the scatter in the previous measurements of HF. OCS has been detected for the first time at the cloud tops by summing 17 lines of the P-branch. The previous detections of OCS refer to the lower atmosphere at 30-35 km. The retrieved OCS mixing ratio varies with a scale height of 1 to 3 km. The mean OCS mixing ratio is ∼2 ppb at 70 km and ∼14 ppb at 64 km. Vertical motions in the atmosphere may change the OCS abundance. The detected OCS should significantly affect Venus' photochemistry. A sensitive search for H₂S using its line at 2688.93 cm⁻¹ results in a 3 sigma upper limit of 23 ppb, which is more restrictive than the previous limit of 100 ppb.