30cm球载红外望远镜(BIT)的指向、偏置导星、跟踪的数学模型和仰角轴装置,偏置导星轴系及其驱动

30cm球载红外望远镜(BIT)是为中国科学院紫金山天文台的“原星的红外观测研究”课题面作。由紫金山天文台和南京天文仪器厂联合研制,是国内首创的点源观测,有偏置导星,能精密指向和跟踪的空间仪器。本文叙述了BIT的指向,偏置导星,跟踪,地平装置倾斜后的影响。几种误差分析,还叙述了BIT的仰角轴装置,偏置导星轴系,驱动系统,轴角指示,润滑等。这些内容对地面的地平式望远镜亦能适用,且可简化,仰角的工作范围为0°～90°,偏置量的工作范围皆为±10°;仰角轴的转速为0.08°/min～6.3°/min,偏置轴的转速皆为0.05°/min～3.75°/min。 1990年6月15日BIT首次飞行试观测。     

乌鲁木齐南山站25m射电望远镜在6cm波段对地面辐射的总功率响应

利用乌鲁木齐南山站25m望远镜6cm系统对观测站周边的地面辐射做了仔细的观测。发现该系统对地面辐射的响应在天空的不同方向有显著的变化。望远镜俯仰为8°时,南方由于高山的影响,对地面辐射的响应已经饱和;甚至在望远镜指向高俯仰(60°)时,总功率响应随不同方位的起伏也可达到0.3K,大于银道面0.01~0.1K的响应,因此它对射电天文观测有显著的影响。根据这些观测数据,建立了6cm系统在不同方向处对地面辐射的响应模型。此模型能够大致描述地面辐射的特征,但尚不能用来完全消除地面辐射的影响。     

全日面磁场与活动监测望远镜轴系升级

在天文观测中,需要望远镜能快速、准确地指向目标天体,并进行稳定跟踪。针对怀柔太阳观测基地(Huairou Solar Observing Station, HSOS)的全日面磁场与活动监测望远镜(The Solar Magnetism and Activity Telescope, SMAT)进行轴系升级,使用伺服电机轴上23位高精度绝对式编码器替代光栅钢带码盘,通过VSOP87行星理论实时计算日面中心位置,使用基于大面阵CCD的高精度导行系统不间断跟踪并记录太阳位置,利用最小二乘法分段拟合太阳实时位置与绝对式编码器数值,建立指向算法并实现日面中心指向。经实测,赤经方向的指向误差约为36.69″,赤纬方向的指向误差约为21.49″,满足全日面太阳磁场望远镜的指向要求,该方法成本低,兼容性高,对于其他赤道式望远镜的升级改造具有借鉴意义。     

天马望远镜连续谱观测系统

天马望远镜是目前亚洲最大的全方位可转动的射电望远镜。连续谱观测对于天马望远镜具有重要意义。主要介绍天马望远镜连续谱观测系统的相关信息及其实现情况,包括:天马望远镜连续谱观测的过程、天马望远镜连续谱观测系统的硬件和软件系统的组成,以及连续谱观测系统的测试观测结果。在C波段6.5 GHz的观测结果表明:连续谱观测系统可实现单点观测和成图观测。修正后指向误差的平均值为2.2′′,均方根误差为4.3′′。目前该系统已用于天马望远镜的连续谱观测,取得了较好的结果,验证了系统的有效性。     

地面光学观测CCD终端图像的采集

近年来,ＣＣＤ迅速广泛地应用于地面光学观测,简单易用的窗口式操作系统在系统软件领域占据统治地位,天图像采集软件也随之需要更新。针对目前常见的地面光学观测系统－天望远镜和ＣＣＤ系统,选用ＤＨ－ＶＲＴ－ＣＧ１００图像采集卡,利用ＶＣ＋＋５．０开发了一套基于Ｗｉｎｄｏｗｓ９８年台的图像采集软件。该软件对于地面光学自动观测具有实用意义,并具备继续扩充的特点,以便同行进行二次开发。     

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。     

交流伺服系统在天文望远镜中的应用研究初探

交流伺服系统在工业控制领域得到了广泛应用,但在天文领域的应用仍处于初级阶段。以中法合作天文卫星(Space multi-band Variable Object Monitor,SVOM)的地面观测设备地基广角相机阵(Ground-based Wide-Angle Camera,GWAC)为研究平台,研究了交流伺服系统应用于望远镜转台控制的可行性。测试了望远镜的跟踪速度控制精度、赤经跟踪精度、最大角速度、最大角加速度、重复指向精度等关键技术指标。测试结果表明,和步进电机系统相比,交流伺服系统在低速控制上具有同样高的精度。在高速控制领域,其调速范围更宽,速度调节更快,运行更平稳,具有明显的优势。另外,还具有低噪声、大转矩、高性价比等优点。实验中还测定了交流伺服系统对Apogee CCD U9000x的干扰,结果表明,交流伺服系统对CCD的干扰很小,在可接受的范围内。总之,交流伺服系统完全可用于中小型天文望远镜的转台控制,特别适用于快速转动和指向的系统。     

1.26米红外望远镜电控系统软件设计与实现

2011年,国家天文台兴隆基地1.26 m红外望远镜进行了全面升级改造。主要讲述望远镜电控系统软件的设计与实现,用于实现望远镜各种观测策略和运动方式的自动化操作。为了提高稳定性和可靠性,软件基于有限状态机原理设计,定义了望远镜的状态集和动作集,以及各个状态间的状态转换图;同时给出了望远镜常见异常及其处理方式,并在本地控制的基础上提供远程控制接口,使得望远镜可方便纳入兴隆基地望远镜集中控制系统。该软件及其设计思想可推广至我国其他中小口径望远镜。     

1.2米地平式望远镜指向模型的研究 (1.全天指向模型的建立)

介绍了云南天文台1.2米地平式望远镜用于天文观测和图像采集处理的方法,建立了新的、独特的全天指向模型,大大提高了该望远镜的指向精度,达到1″,并在多年的实际应用中得到验证。     

地平式望远镜AGU标校模型与仿真试验

地平式望远镜中自动导星单元(Automatic Guiding Unit,AGU)用于导引主视场观测恒星,其视场仅约1'.控制软件需要控制AGU在二维运动,确保选择的参考星能够进入AGU视场;并且当参考星离开原来位置时能够给出偏差值以修正望远镜指向,从而实现主视场对恒星的凝视观测.基于球面投影坐标系分别为AGU的中心指向和像场旋转建立齐次方程修正模型,使得AGU可以按照赤道坐标指向恒星,并且当恒星偏离时能够给出误差值.     

All‐spherical telescope with extremely wide field of view

An all‐spherical catadioptic telescope with the angular field of view of several tens of degrees in diameter and spherical focal surface is proposed for the monitoring of large sky areas. We provide a few examples of such a system with the apertures up to 800 mm and the field of view 30° and 40° in diameter. The curvature of the focal surface is repaid by high performance of the telescope. In particular, the diameter of a circle that includes 80% of energy in the polychromatic image of a star is in the range 1.″4–1.″9 across the field of 30° size and 2.″2–2.″9 for the field of 40° size. Some ways of working with curved focal surfaces are discussed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A new type optical fiber T.V. adaptor-link between telescope and spectrography

A new type of optical fiber T.V. adaptor-link device is developed to bring a star image at the focus of a Schmidt telescope to the slit of a spectrograph located at the observing floor, as well as part of the field, to a T.V. monitor for acquisition and guiding purposes. The device is constructed by 60 000 thin glass fibers (18 micron in diameter and 1.2 m in length) used as the adaptor, and a single long (20 m) thicker (25 micron core diameter) fused silica fiber used as the link between the telescope and the spectrograph. The 60 000 thin fibers are arranged in a 4 by 5 mm rectangular array with the link built in the center of the field. With the adaptor-link the astronomer can easily acquire the star on the T.V. monitor, transfer the star image through the link to the slit of the spectrograph and guide the star during observation.     

Discovery of Three Variable Stars in Direction toward NGC 4565

We present the results of a variable star search in a field next to the edge-on galaxies NGC 4565 from the archive data of Beijing-Arizona-Taibei-Connecticut Multicolor Sky Survey. Three new variable stars were discovered. Based on spectra obtained from the 2.16 m NAOC telescope, we identify two of these as RR Lyr stars and one as a special T Tauri star.     

Astrokit-an efficient program for high-precision differential CCD photometry and search for variable stars

Having a need to perform differential photometry for tens of thousands stars in a several square degrees field, we developed Astrokit program. The software corrects the star brightness variations caused by variations of atmospheric transparency: to this end, the program selects for each star an individual ensemble of reference stars having similar magnitudes and positions in the frame. With ten or more reference stars in the ensemble, the differences between their spectral types and the spectral type of the object studied become unimportant. A strokit searches for variable stars using Robust Median Statistics criterion, which allows candidate variables to be selected more efficiently than by analyzing the standard deviation of star magnitudes. The software allows very precise automatic analysis of long inhomogeneous sets of photometric observations of a large number of objects to be performed, making it possible to find “hot Jupiter” type exoplanet transits and low-amplitude variables. We describe the algorithm of the program and the results of its application to reduce the data of the photometric sky survey in Cygnus as well as observations of the open cluster NGC188 and the transit of the exoplanet WASP-11 b /HAT-P-10 b, performed with the MASTER-II-URAL telescope of the Kourovka Astronomical Observatory of the Ural Federal University.     

云南-香港宽视场巡天新发现的一个磁活动双星系统

云南-香港宽视场巡天新发现了一个磁活动双星系统,其轨道周期为0.60286 d.利用云南天文台1 m光学望远镜附加CCD (Charge-Coupled Device)相机,观测得到了这个双星系统的V、Rc双色光变曲线,结果表明该系统食外存在明显的测光畸变.借助云南天文台丽江2.4 m望远镜附加云南暗弱天体光谱成像仪(Yunnan Faint Object Spectrograph and Camera, YFOSC)对该双星系统的分光观测,测定了该双星系统主星的视向速度曲线并发现该系统的主星表面存在着强烈的色球活动,从而证明系统的光变曲线畸变源自主星的黑子活动.使用W-D (Wilson-Devinney)程序分析上述观测得到的光变曲线和视向速度曲线,得到了该双星系统的轨道参数以及黑子参数.最后,对该系统的特性进行了讨论并对未来的工作进行了展望.     

Super resolution for astronomical observations

In order to obtain detailed information from multiple telescope observations a general blind super-resolution (SR) reconstruction approach for astronomical images is proposed in this paper. A pixel-reliability-based SR reconstruction algorithm is described and implemented, where the developed process incorporates flat field correction, automatic star searching and centering, iterative star matching, and sub-pixel image registration. Images captured by the 1-m telescope at Yunnan Observatory are used to test the proposed technique. The results of these experiments indicate that, following SR reconstruction, faint stars are more distinct, bright stars have sharper profiles, and the backgrounds have higher details; thus these results benefit from the high-precision star centering and image registration provided by the developed method. Application of the proposed approach not only provides more opportunities for new discoveries from astronomical image sequences, but will also contribute to enhancing the capabilities of most spatial or ground-based telescopes.     

Field optimization and CCD data simulation for the antarctic International Concordia Explorer Telescope (ICE‐T)

We performed extensive data simulations for the planned ultra‐wide‐field, high‐precision photometric telescope ICE‐T (International Concordia Explorer Telescope). ICE‐T consists of two 60 cm‐aperture Schmidt telescopes with a joint field of view simultaneously in two photometric bandpasses. Two CCD cameras, each with a single 10.3k × 10.3k thinned back‐illuminated device, would image a sky field of 65 square degrees. Given a location of the telescope at Dome C on the East Antarctic Plateau, we searched for the star fields that best exploit the technical capabilities of the instrument and the site. We considered the effects of diurnal air mass and refraction variations, solar and lunar interference, interstellar absorption, overexposing of bright stars and ghosts, crowding by background stars, and the ratio of dwarf to giant stars in the field. Using NOMAD, SSA, Tycho‐2 and 2MASS‐based stellar positions and BVIJH magnitudes for these fields, we simulated the effects of the telescope's point‐spread‐function, the integration, and the co‐addition times. Simulations of transit light curves are presented for the selected star fields and convolved with the expected instrumental characteristics. For the brightest stars, we showed that ICE‐T should be capable of detecting a 2 R_Earth Super Earth around a G2 solar‐type star, as well as an Earth around an M0‐star – if these targets were as abundant as hot Jupiters. Simultaneously, the telescope would monitor the host star's surface activity in an astrophysically interpretable manner (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Pulsations of the B[e]-type component in the CI camelopardalis system

CI Cam is a well-known B[e]-type star and an X-ray transient, which underwent a powerful outburst in all parts of electromagnetic spectrum in 1998. An extensive V-band photometric monitoring revealed that rapid variability of CI Cam on the time scale of several hours is due to the pulsations of the B4 III–V type component. High-precision CCD photometry of the star was performed with the 50-cm Maksutov (meniscus) telescope of the Crimean station of the Sternberg Astronomical Institute of Moscow State University in December 2006 during the quiescent state of the star. The data are analyzed using the methods of discrete Fourier transform and by modeling of the light curve. The amplitude spectrum of the star is dominated by two peaks corresponding to the periods of 0.41521 and 0.26647 days with the period ratio close to 3:2. At least two pulsation modes are excited and the star exhibits signs of the resonance between modes.     

A flare in the mira X oph

Before the observation of the 1974 U Ori eruption, it was considered that the Mira stars had only some regular OH variations. With this eruption, we realized that sometimes flares can occur in this type of star. In the course of an OH Mira star monitoring programme with the Nançay radio telescope, we have discovered a new eruptive type of OH maser emission in several sources. Especially, in early 1992, we observed a quickly rising 1665 Mhz emission in the Mira X Oph. The main characteristics of this flare were: large flux variations independent of the light curve; large degree of circular polarization; radial velocity emission close to the stellar velocity.     

Microvariability of spectral line profiles and magnetic fields of early-type stars: <Emphasis Type="Italic">ζ</Emphasis> Ori A

We report the results of spectropolarimetric observations of the supergiant ζ Ori A made with 6-m BTA telescope of the SAO RAS. We found regular variations of line profiles in the spectrum of the star with a period of 1–3 hours and point to their possible association with nonradial photospheric pulsations. We also searched for a possible weak magnetic field in ζ Ori A, but observations did not confirm the existence of such a field in the star considered.