太阳光谱望远镜鬼线强度测量方法及初步结果

介绍了云台太阳光谱望远镜光栅鬼线强度测量方法。给出了２级光谱罗兰鬼线强度的初步测量结果,为母线强度的０．０４９％,结果表明光栅的质量优良,鬼线对光谱测量的影响非常小,一般情况下在光谱资料处理中可以不必考虑鬼线强度的改正。     

40cm水平式太阳光谱仪调试和性能测定

本文介绍了光谱仪光路装调原理、方法、步骤以及基本性能测定原理和所用设备。 给出了仪器D区光栅二级罗兰鬼线总强度约0.17％;仪器轮廓半宽为0.05A,形状基本上对称;实际分辨本领为117000;散射光总量≤2％。 装调结果达到设计要求。仪器性能良好。     

云台太阳光谱仪D区散射光测量

本文介绍了太阳光谱仪散射光测量的原理和基本方法;给出了我台水平式太阳光谱仪在D区横向散射光(包括鬼线强度),纵向散射光和漫射光的测量结果。由此说明了这台光谱仪质量良好,适宜作太阳光谱的定量研究工作。     

离面工作条件下光谱仪多光栅槽型优化设计

在大规模多波段成像和无缝光谱巡天中,无缝光谱巡天极限星等在一定程度上受无缝光谱效率和无缝光谱光栅衍射效率制约,针对无缝光谱仪中布置在焦面附近的光栅开展衍射效率优化设计研究.在光栅衍射效率的计算中采用严格耦合波分析方法,并在优化算法中综合采用模式搜索法和差分进化算法相结合的方法,得到了衍射效率高同时满足工程化要求的最优化槽型.模式搜索法能快速地收敛到局部最优值,差分进化算法具有全局择优的特点,两者结合提升了运算效率和结果的可靠性.针对无缝光谱仪中工作在不同波段、不同入射角和不同离面角的多块光栅优化衍射效率.优化结果表明,通过合理控制槽型,所有光栅在闪耀波长处的理论平均衍射效率均可达到0.83.     

厚片CCD标准谱线证认及光栅转角测定

自1987年以来,云台库特摄谱仪改装使用了CCD相机,将可测波段扩展到红外。本文经实测证认了适用于扩展后的7000—11700埃的Fe-Ar比较光源的标准光谱谱线表。并精确测定了仪器改装后的光栅转角计算公式,还讨论了仪器综合效率、光栅定位精度、滤光片的使用等问题。     

中等贫金属星高分辨率光谱分析 I.光谱数据与等值宽度

利用北京天文台兴隆观测基地2.16米望远镜的折轴阶梯光栅摄谱仪，获得了一批中等贫金属星的高分辨率，高信噪比光谱，通过MIDAS软件包对其中7颗中等贫金属星进行了光谱处理，得到了它们的等值宽度，最后给出院 样本恒星的等值宽度及误差分析。     

用CCD作光谱观测时应注意的几个问题

本文给出了云台CCD系统在Coudé摄谱仪f=1900照相机上作光谱观测中一次可摄波段,光栅转角,波段滤光片等重要参数的计算选择和应注意的问题。     

一米新真空红外太阳望远镜多波段光谱仪光谱弯曲分析

在太阳长狭缝光谱观测中,光谱的狭缝方向和色散方向应该分别与CCD探测器的两个边缘平行。但实际上,由于狭缝、光栅、CCD探测器的机械安装精度等原因,会造成他们之间的位置关系不匹配,导致得到的太阳光谱总是存在一定的倾斜和变形。即使有时这些倾斜很微小,也会对太阳光谱的平场计算造成严重影响,从而影响整个光谱数据的处理过程。对抚仙湖1 m新真空红外太阳望远镜多波段光谱仪得到的一组Hα光谱数据的倾斜量做了测量和分析,并讨论了其对太阳光谱平场计算的影响。     

天体高分辨率软X射线光谱的实验测量标定

近年来,利用实验装置测量的原子数据对一些天文观测难题(包括弱线辐射、诊断特征线比的标定和反常线流量比)的解释取得了很大的进展。为测量高电荷铁离子的高分辨率软X射线光谱,在国家天文台EBIS-A平台上设计并搭建了一个超高真空平场光谱仪。在单缝模式下,使用1 200槽/毫米变间距的衍射光栅,测量波长为11.5～19.8 nm。针对光谱仪的测量结果,对可能测量的辐射进行理论预测。根据电子束离子阱的工作原理,基于Chianti数据库对海德堡电子束离子阱(Heidelberg-Electron Beam Ion Trap, EBIT)极紫外光谱数据(11.5～14.5 nm)进行分析。首先,建立线性回归模型校准由实验系统引起的线强度峰值位置的偏移;然后,通过碰撞辐射模型模拟的不同离化态铁离子的软X射线光谱确定实验测量中Fe VIII,Fe XIX-XXIII的线辐射,并较好地呈现观测谱。此外,在13.292 5±0.101 78 nm处发现了相对Fe XXIII跃迁线强度较弱的Fe XIX和Fe XX的混合线,而观测到的光谱没有分辨出这些弱线。因此,接下来的实验测量可以参考这一预测结果检验光谱仪的性能。     

两个日珥的分光光度研究

关于日珥光谱研究的主要问题,作者在以前的工作中已经详细描述.这篇文章只包括对1958年11月11日日珥[以下简称日珥(1)]和1959年6月2日日珥[以下简称日珥(2)]的分光光度研究结果.1.观测和归算本项研究工作所用的观测资料是作者在苏联科学院克里米亚天文台太阳塔取得的.日珥(1)和(2)的光谱分别用平面光栅摄谱仪和阶梯光栅摄谱仪拍摄.光谱底片的归算工作是印春霖同志在紫金山天文台用МФ—4型自记显微光度计完成的.观测和归算     

Spectrographic study of Nova Cygni 1978 (V1668 CYG)

Nova Cygni 1978 was observed from October 11 to December 23, 1978 at the Beijing Observatory with the grating spectrograph attached to the Naismith focus of the Schmidt telescope. This paper gives postmaximum photographic magnitudes, identification of the spectral features, emission line structures, intensity ratios of some emission lines and the temperature of the underlying star.The main spectral lines in wavelength range from October 11 to 30 are those of the following atoms or ions: H, FeII, NII, TiII, [0I], NIII. From November 10, lines of [0III], HeI and Hell become visible one after the other. The emission line H_α shows three components of which the most redshifted is the strongest. In turn, each component is split into a number of secondary peaks. Temperature of the underlying star increases with decline of the nova brightness. The upper limit of temperature may be 120000 K.     

无缝光谱仪用紫外透射闪耀光栅的制作

无缝光谱巡天是如今国际天文学研究的重点方向, 相比较地基巡天任务, 空间巡天可获取更多紫外波段与红外波段的光谱信息, 其发展受到色散元件的制约, 针对紫外波段的核心色散元件---紫外透射闪耀光栅开展了一系列研究. 通过全息干涉光刻产生图形, 离子束垂直刻蚀将图形转移至基底形成光栅掩模, 利用光栅掩模对倾斜离子束的遮挡作用, 使得槽底不同部位受到离子束的轰击通量不同, 从而获得非对称的槽形结构. 实验分析了倾斜离子束刻蚀中沉积物的主要组成以及对槽形和闪耀角度的影响, 并在去除沉积物影响的情况下, 成功制作了线密度为333lines/mm, 闪耀角度分别为13.2°、10.5°的紫外透射闪耀光栅, 峰值衍射效率分别可达理论值的88%以及92%, 为制作高衍射效率紫外透射闪耀光栅奠定了基础.     

Limb observations of the 12.32-micron Mg I emission line during the 1994 annular eclipse

We determined the limb profile of the extremely Zeeman-sensitive emission line of Mg i at 12.32 m (811.58 cm–1) during the May 1994 annular eclipse, using the 3.5-m ARC telescope at the Apache Point site on Sacramento Peak, New Mexico. Spectra were recorded at 0.1 cm–1 spectral resolution and 1 s time resolution using a cryogenic grating spectrometer. The time derivatives of the observed line energy and continuum intensity were used to infer high-resolution profiles of the solar limb. Data were obtained at second contact only, since clouds prevented observations at third contact. We find that the emission line energy peaks very close to the 12 m continuum limb. This agrees with our result from the 1991 total eclipse over Mauna Kea, and also with non-LTE radiative transfer theory for this line, which predicts an upper-photospheric origin. However, in 1991, line emission remained observable as high as 2000 km above the continuum limb, whereas the 1994 data show observable emission to only 500 km. This difference greatly exceeds any applicable errors, or sensitivity differences in either data set, and must be attributed to spatial and/or temporal inhomogeneities in the solar limb emission of this line. We discuss possible causes of these inhomogeneities, and implications for observations at far-IR and submillimeter wavelengths.     

The performance of a large echelle grating in a solar spectrometer

A number of tests of a large diffraction grating are described. It is shown that useful information about the performance of the grating in a spectrometer can be obtained from an analysis of the diffracted wavefront by the method of Stroke. Comparison of the instrumental profile at three wavelengths strongly suggests that the influence of changes in the angle of diffraction on the profile cannot be neglected. A resolving power of 6.9 × 10⁵ is attained at 6328 Å. At the same wavelength the first order Rowland ghosts in the ninth order of diffraction have an intensity of only 8 × 10^-4 of the parent line. The influence of stray light on the central intensities of deep Fraunhofer lines is shown to be small but by no means negligible.     

Peculiarities of the mode of oscillations in a floccule and its neighborhoods at different chromospheric levels

The behavior of oscillations in the quite solar chromosphere under a coronal hole at several heights has been investigated. The properties of oscillations in cell, network, and weak-floccule areas have been analyzed. A time series of spectrograms in three ionized calcium lines, the Ca II K and H resonance doublet lines and the infrared Ca II 849.8-nm triplet line, was used. The observations were carried out at the horizontal solar telescope of the Sayan Observatory. The goal of this study was to compare the distributions of spectral power in various frequency ranges and their variations for selected spatial areas at different heights of the chromosphere. Particular attention was paid to the weak floccule due to a noticeable difference in the central intensity distribution between the K and H lines and the 849.8-nm line. A spectral Fourier analysis was used. The central intensities of the observed spectral lines, the K-index, and the equivalent width (the latter for the 849.8-nm line) were chosen as oscillation parameters. The studies have shown that the main intensity oscillation power at both atmospheric levels is concentrated at frequencies below 9 mHz. In the distribution of intensity oscillation power at different chromospheric levels, there are differences clearly distinguishable in the floccule. Powerful five-minute oscillations whose main peak frequency decreases with height, while the amplitude increases have been detected in the central part of the floccule. This result confirms the assumptions recently pointed out in the literature that vertical magnetic field concentrations can serve as a channel for the passage of low-frequency oscillations from the photosphere to the chromosphere in faculae. The intensity oscillation power in the frequency ranges under consideration has turned out to decrease with height, on average, for the entire observed spatial area. This may be related to the loss of part of the wave energy through the reflection, dissipation, and transformation of wave modes in the magnetic canopy layer. An area with a low brightness but powerful oscillations at about 3.3 mHz covering a considerable range of heights probably pertaining to “magnetic flashers” has been isolated in the telescope’s field of view.     

A Note on Saturation Seen in the MDI/SOHO Magnetograms

A type of saturation is sometimes seen in sunspot umbrae in MDI/SOHO magnetograms. In this paper, we present the underlying cause of such saturation. By using a set of MDI circular polarization filtergrams taken during an MDI line profile campaign observation, we derive the MDI magnetograms using two different approaches: the on-board data processing and the ground data processing, respectively. The algorithms for processing the data are the same, but the former is limited by a 15-bit lookup table. Saturation is clearly seen in the magnetogram from the on-board processing simulation, which is comparable to an observed MDI magnetogram taken one and a half hours before the campaign data. We analyze the saturated pixels and examine the on-board numerical calculation method. We conclude that very low intensity in sunspot umbrae leads to a very low depth of the spectral line that becomes problematic when limited to the 15-bit on-board numerical treatment. This 15-bit on-board treatment of the values is the reason for the saturation seen in sunspot umbrae in the MDI magnetogram. Although it is possible for a different type of saturation to occur when the combination of a strong magnetic field and high velocity moves the spectral line out of the effective sampling range, this saturation is not observed.     

New absolute measurements of the solar spectrum 310–685 nm

During 1986–1989 at the high-altitude station on the Peak Terskol, Caucasus (h = 3000 m) absolute measurements of the solar disk-centre intensity were performed. The observations were carried out with the specialized solar telescope (D = 23 cm,F = 3 m) and grating spectrometer (F = 2 m, grating 140 × 150 mm, 600 grooves mm^–1). The ribbon tungsten lamps used for absolute calibration were calibrated to the USSR standard of spectral intensity and were also compared with the irradiance standard of the PMO/WRC (Davos, Switzerland), with the lamps used in the Alma-Ata Observatory (Kazakhstan) and in Simferopol University for absolute measurements of stellar spectra. Methods and apparatus were improving step by step during 1985–1988. Special care was paid to the study of all possible sources of errors, in particular to the method of correction for atmospheric extinction, to polarization properties of optical elements of the apparatus, and to establishing the most reliable absolute calibration system. Finally, the observations performed during 1989 utilized only the refined methods and apparatus. As a result, the absolute integrals of the solar disk-centre intensity for 1-nm wide spectral bands in the range 310–685 nm are available. We estimate the total error is 2.5% at 310 nm and 2.1% at 680 nm. The absolute irradiance for 5-nm wide spectral bands is also obtained. We compare our results with results by Neckel and Labs (1984), with the irradiance filter measurements performed in PMO/WRC and calibration of the Sun's spectral irradiance to the stellar irradiance standard Vega by Lockwood (1992). Our results show a systematic difference with data by Neckel and Labs in the near-ultraviolet. The results by Neckel and Labs are probably underestimated in this spectral range by 8%.Deceased 20 January 1994.     

Luminosity dependent study of the high mass X-ray binary pulsar 4U 0114 + 65 with ASCA

Here we report the spectral characteristics of the high and low states of the pulsar 4U 0114 + 65 and examine the change in the parameters of the spectral model. A power law and a photoelectric absorption by material along the line of sight together with a high energy cut-off suffice to describe the continuum spectrum in both the states. A fluorescence iron line at ∼6.4 keV is present in the high as well as in the low state, though it is less intense in the latter. The photon index, cut-off energy and e-folding energy values hardly show any discernible change over the states. We compare these spectral characteristics as observed with ASCA with those of other satellites. We also compare the spectral characteristics of 4U 0114 + 650 with other X-ray sources which show intensity variation at different time scales.     

Membership of stars in faint galactic open clusters

Low-dispersion spectra of the order of 1000 Å mm^-1 have been obtained for stars in several faint galactic clusters with a transmission grating placed in front of the photographic plate at the Cassegrain focus of the Kavalur 102-cm telescope. The intensity distribution in the shorter wavelengths has been taken as the principal criterion for the spectral classification of the individual stars in the area covered by the photographic plate. The uncertainty in this procedure has been found to be about two spectral subclasses. A combination of these spectral classes with the visual magnitudes derived from the image diameters on the POSS charts provide the HR diagrams for each cluster area. These diagrams are adequate to establish the cluster membership of any star to a first approximation. This technique has been tested on six galactic open clusters, four of which are well-studied. We find good agreement both in terms of the ages of the clusters and individual stellar membership.