GC和SAOC星表的系统差讨论

应用Bien等人计算星表系统差的方法，计算了GC和SAOC星表相对于FK5星表的系统差。计算结果与GC经FK4得表作中间星表所得的结果作了比较；两比较的结果表明只要有较多的共同星，两种方法获得的结果基本一致，并且将SAOC星表和AGK3，Perth70星表的系统差也进行比较，除近天极附近的区域外，所得结果一般都符合较好。     

Perth70星表系统差的分析

根据Bien等人提出的方法计算了（FK5－Perth70）的星表系统差，结果表明：（1）Perth70星表相对于FK5的赤经系统变化，与FK4相比，比较平稳而且波动也较小，系统差在南天的高赤纬区较为明显。（2）在赤纬系统中Perth70星表和FK4有相似的波动。（3）Perth70星表几乎没有星等差存在。因此，Perth70星表可以认为是一个精度很高的南天星表。     

1980颗GC星的精确位置与自行

本文发表1980颗GC亮星星表.其中1830颗星是我国大地测量星.这些GC星的自行和位置参数是利用国内外九部星表统一归化到FK5星表系统后重新计算确定的.它们的精度相当于目前国际上最好的同类星表的精度.恒星位置的平均精度为     

FK5相对于依巴谷星表的系统差及其对EOP的影响

依巴谷星表在建立时已做到与以河外射电源定义的国际天球参考系（ICRS）相符合,而ICRS系统与由FK5星表实现的由J2000.0平赤道和平春分点定义的赤道坐标系统相一致。估计依巴谷星表的系统误差小于0.1mas,因此,依巴谷星表成为描述光学观测确定的地球定向参数（EOP）的一个更为均匀的参考系。本文主要讨论了FK5和依巴谷星表之间的星表系统差（FK5－Hip）,并用中国光电等高星表来检验（FK5－Hip）星表系统差的结果,并估算了星表系统差（FK5－Hip）对EOP的影响。     

关于苏联测地星表的分析和使用

本文对苏联测地星表(CGS)进行了较全面的统计分析.主要内容包括:1.统计了CGS星表的内部精度,并分析了该星表的误差分布特性.主要结果列于表3和表4.2.利用1098颗CGS和FK4_(sup)的公共星,计算了CGS与FK5星表的系统差.CGS星表相对于FK5星表的系统改正,分别列在表7-9中.3.CGS星表中恒星位置和自行参数误差较大(相对于KF5星表)的一些星,分别列于表10.1、表10.2和表11.对这些大的误差产生的影响进行了分析、讨论.在这基础上我们指出了在使用CGS星表时应该注意的一些问题,并提出了有关建议.     

FK5系统中几个星表系统差的比较

本由云南天台的光电等高星表（YUA），La Palma子午星表CAMC5，以及中国光电等高第三总星表（GCA），东京天台子午星表9PMC85）相对于FK5系统差的分析。得到以下结果：FK5星表的赤经系统相对比赤纬系统平稳；在赤纬δ＝＋40°附近由两个子午星表反映出约±0.″1、方向相反的系统差波动，能是由观测误差而引起，而不是FK5本身的系统误差。     

陕台光电等高仪(Ⅰ型)初始星表(摘要)

1978年初至1981年初,我们用陕台光电等高仪(Ⅰ型)进行了专门的星表观测。获得的星表包括777颗两次过等高圈的恒星的赤径改正△α和赤纬改正△δ。其中有FK4星357颗,FK4supp星189颗,GC星231颗。对于|cosq|≤0.3的星没有计算△δ。所有FK4星△α、△δ的平均精度分别为±0.0036和±0″.063。另外,还给出了43颗一次过等高圈的恒星的赤经改正△α和2颗星的赤纬改正△δ。为有效地扩充待测星数,除在时间、纬度观测纲要即基本组(2小时一组)内插入适当数目的待测星外,我们增加了星表组(1小时一组)。观测方案是:星表组——基本组——星表组——星表组——基本组——星表组或者星表组——基本组——基本组——星表组。星表的系统完全由基本组的FK4星决定。将各基本组化到平均系统以后,所有的星表组及基本组内的插入星直接相对于这个平均系统求其残差平均值。     

射电星的光学位置和自行

1980－1981年期间，上海天台Ⅱ型光电等高仪和丹容等高仪（OPL No.14）共观测了15颗射电星。在FK5星表系统中得到了这些射电星的位置，并由这些观测位置与它们在其他星表例如G C，CAMC和W5／50中的相应位置进行比较，求得了这些射电星的自行。把我们求得的这些射电星的自行和PPM及CAMC星表中的相应自行作了比较，相互符合很一致。     

测定天文大气折射和建立电磁波折射延迟实测模型(Ⅱ)-采用依巴谷星表作为工作星表

叙述了测定大气折射对工作星表的要求和星表系统误差的影响,并通过FK5星表相对于依巴谷星表的系统误差,来说明以往的各种基本星表都不适用的原因;文章说明了依巴谷星表所列星位置不含随天区而异的系统误差的特性,分析了该星表问世时的精度和十多年后的今天仍能达到的精度,说明它可以作为这种测定的工作星表,从而为直接测定天文大气折射值和折射率差提供了一个重要的条件;文章还介绍了依巴谷星表的星等分布,认为只需选用亮于6mag的依巴谷星,这一星等范围,为制定专用测量仪器终端的设计方案提供了依据。     

中国光电等高仪系统的等高总星表(GCPA)

本文介绍中国光电等高仪系统的等高总星表(GCPA)。它以光电等高仪得到的四部初始星表的系统差组成赤经和赤纬综合系统,再将用Danjon等高仪得到的四部初始星表归化到综合系统上。总星表共有1579颗星,1541个△α值,1131个△δ值.所有△α和△δ的平均精度分别为±3.3ms和±0.058,其中FK4星的相应值分别为±2.3ms和±0.042.由两个和两个以上仪器观测得到的FK4星有485个△α值和349个△α值,其外部符合精度分别为±3.8ms和±0.041。最后给出了由GCPA确定的FK4的系统改正,并与有关星表做了比较。     

星表系统差及其计算方法

本文对星表系统差的性质进行了讨论，并分析和评估了目前常用的星表系统差计算方法的优、缺点，从而提出了一个新的星表系统差计算方法．同时也提出了星表系统差计算精度的检验标准．最后对用不同方法计算的系统差进行了分析比较．结果表明，新方法的系统差计算精度好于目前常用的解析方法．     

Observing programs for the Pulkovo Horizontal meridian circle

Observing programs are discussed for the Pulkovo automatic horizontal meridian circle. The instrument is highly efficient and yields precise and accurate positions. We prepare an observing program of faint FK5 stars with the aim of improving on the system of this catalogue and also prepare a program of observations of IRS reference catalogue stars.     

FK5星表和依巴谷星表的比较

由ＦＫ５星表和依巴谷星表在不同历元上的比较、检测和讨论了ＦＫ５星表的系统差．结果表明，ＦＫ５星表的自行系统差可能是影响ＦＫ５星表位置系统差的主要来源．在一些研究工作中，例如在依巴谷星表系统中研究地球自转的长期变化或以前的照相观测结果的重新归算，需要考虑依巴谷星表自行个别误差的影响     

The galactic warp and rotations of the fundamental system

The proper motion in galactic latitude of O-B stars enables us to detect the kinematic behaviour of an optical counterpart of the large-scale warp of the HI gas layer in our Galaxy. A selected set of the proper motions of about 350 O-B stars within 3kpc from the sun (R₀=8.5kpc) is analyzed on the proper motion systems of N30, FK4, and FK5. A remarkable differece in the kinematic behaviour of the warp appears between the old systems (N30 and FK4) and FK5-system. On the old systems, the O-B stars in the belt 8.5kpcR<9.5kpc exhibit a systematic z-motion upward from the galactic plane forl180° and downward forl>180° with the mean proper motions of about ±0".4/century, respectively. On the other hand, the results on the FK5-system show no meaningful systematic z-motion, even though the O-B star layer exterior to the solar circle is inclined (3°) with respect to the galactic plane. These findings can neither be inferred from the model of the oblique material flow nor from the concepts of the precessional stellar rings and of the bending oscillation of a stellar disk. The remarkable difference in the kinematic behaviour of the warp, appearing between the old and new systems, is caused mainly by the conversion of the proper motions on the old systems into those on the J2000.0 frame. The conversion near the galactic plane is given by µ_b(FK4(J2000.0))–µ_b(FK4)–0.50 sinl/century. The implication of this relation is discussed in connection with the warping motion of stars detected here.     

M dwarfs at large heliocentric distances

We present an analysis of the faint M star population seen as foreground contaminants in deep extragalactic surveys. We use space-based data to separate such stars from high-redshift galaxies in a publicly available data set, and consider the photometric properties of the resulting sample in the optical and infrared. The inferred distances place these stars well beyond the scaleheight of the thick disc. We find strong similarities between this faint sample (reaching   i '_AB= 25  ) and the brighter disc M dwarf population studied by other authors. The optical–infrared properties of the bulk of our sources spanning 6000 Å-4.5 μm are consistent with those 5–10 mag brighter. We also present deep spectroscopy of faint M dwarf stars reaching continuum limits of i '_AB≈ 26, and measure absorption-line strengths in the CaH2 and TiO5 bands. Both photometrically and spectroscopically, our sources are consistent with metallicities as low as a tenth solar: metal-rich compared with halo stars at similar heliocentric distances. We comment on the possible massive astrophysical compact halo object (MACHO) identification of M stars at faint magnitudes.     

The General Catalogue of Photoelectric Astrolabe Stars (GCPA) based on the Chinese photoelectric astrolabe system

The General Catalogue of Photoelectric Astrolabe Stars (GCPA) based on the Chinese photoelectric astrolabe system is described. It is a combined system of right ascension and declination synthesized from four primitive star catalogues' obtained with the photoelectric astrolabe. Four other primitive catalogues obtained with the Danjon astrolabe are reduced to the combined system and added to it. GCPA contains 1579 stars, 1541 Δα values and 1131 Δδ values. The overall average accuracy is ±3.3 ms in Δα, and ±0″.058 in Δδ; for the FK4 stars, the corresponding values are ±2.3 ms and ±0″.042. FK4 stars observed by two or more instruments gave 485 Δα values and 349 Δδ values, with external accuracies ±3.8 ms and ±0″.041. Corrections to the FK4 system as determined by GCPA are given and a comparison with the relevant catalogues is presented.     

用于自适应光学系统的激光引导星

自适应光学系统应用于天文观测时应满足一些技术要求,其中的关键技术之一是自适应光学系统为了对畸变的光波进行采样,需要在其很小的等晕角内有足够的信标强度。激光引导星,即人造信标,就是解决这种问题的方法之一。特别是在观测天文暗目标时,其自身的光强度不能为有探测提供信息,激光引导星就蛤得非常重要。根据国际上的最新进展对激光引导星技术给予了介绍。重点介绍了激光引导星的局限性,对近几年提出的对激光引导星可能的     

Speckle interferometry as a method for detecting nearby extrasolar planets

The applicability of the technique of speckle interferometry to the problem of detecting faint planetary and stellar objects around nearby stars is considered. Direct resolution could not be expected to reveal planetary objects, although many faint stellar objects should be detectable with a speckle camera of large dynamic range. The most promising possibilities lie with the approximately 100 nearby visual binaries with separations ?3 arcsec. Continued speckle interferometric observation of these systems could detect perturbations with amplitudes similar to those detectable by an ideal astrometric telescope. A simple scheme for measurement the fringe spacing in the composite spatial frequency power spectrum of the visual binary Eta Orionis indicates that relative separations with accuracies of 0″.002 in each coordinate are attainable. Use as reference stars of faint background stars lying within the isoplanatic patch of a nearby star is also considered.     

The extension of the fundamental system to fainter magnitudes

During the past 100 years the fundamental system has developed from a small list of 623 bright stars to one of 1535 stars. The compilation of the next fundamental catalog, the FK5, will involve the addition of some 3200 stars and will extend the system to magnitude 9.0. A number of criteria were used for selecting the 2000 stars in the seventh to ninth magnitude portion of the extension, the Faint Fundamentals. These criteria include distribution in magnitude and spectral type, quality of the observational histories, mean errors of the proper motions and distribution over the sky. These criteria have proven difficult to satisfy, especially at the faint end of the magnitude range and in the Southern Hemisphere.