Design of 2-M to 6-M Liquid Mirror Containers

A new design is proposed for large (up to 6-m) liquid mirror containers. The design uses Kevlar, foam and aluminum, as in previous designs, but with a different configuration that makes the container lighter, stronger and more rigid. The results of finite element analysis are presented, consisting in the deformations due to temperature changes and to weight, and in the security factor for each material when maximum constraints are applied. Tilt rigidity is also analyzed. They show that the composite material construction technique gives a good performance up to 6 m diameters. The figures and tables contained in this paper can be used as recipes to build containers having diameters between 2 and 6 m. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solar radio burst (type III)

This article describes the observations of a type III radio burst observed at 103 MHz simultaneously by the two radio telescopes situated at Rajkot (22.3°N, 70.7°E) and Thaltej (23°N, 72.4°E). This event occurred on September 30, 1993 at about 0430 UT and lasted for only half a minute. The event consisted of several sharp spikes in a group. The rise and fall time of these are comparable, however the peaks of individual spikes varied by a factor of four. The comparison of these observations with the data of solar radio spectrograph HiRAS indicates that this was a metric radio burst giving highest emission at about 103 MHz.     

VLA observations of extreme hydrogen deficient stars

VLA observations at 2 and 6 cm have been obtained for six hydrogen-deficient stars R CrB, HD 160641, BD — 9°4395, V348 Sgr, MV Sgr and Sgrv Upper limits to the massloss rates have been estimated for some of these using the upper limits to the radio flux density. National Radio Astronomy Observatory’s Very Large Array is operated by Associated Universities Inc. under contract with National Science Foundation, USA     

PIN调制器在太阳射电快速记录系统中的运用和性能检测

本文简要地介绍了云南天文台太阳射电快速记录系统ＰＩＮ调制器的运用，描述了该器件的结构原理和性能检测，并给出了测试结果     

基于GIS空间统计分析的广电收视率评估研究——以北京市广电收视覆盖分析系统为例

本文将GIS空间信息统计分析手段应用于广播电视收视率的评估,以层次分析法为基础进行改进,采用抽样调查的方法确定权重,提出较为合理的基于空间信息统计方法的广电人口覆盖分布模型并加以软件实现。以北京市为研究区域,经导入多个版本人口数据实验,发现这种评估方式较好地修正了传统的仅仅按照面积评估覆盖率的评估模型,对于提高广电行业的信息化管理水平具有一定意义。     

The near infrared camera on the W.M. Keck telescope

The near infrared camera (NIRC) was used for a science demonstration run on the Keck telescope during 16–24 March 1993. The camera used a 256×256 InSb array manufactured by Santa Barbara Research Corporation. Observations were obtained using narrowband and broad band filters from 1 to 2.4 microns, and grisms with a spectral resolution of 0.6 percent in the J, H and K atmospheric windows. The instrument was fully background limited over the entire wavelength range. The sky background was quite low, reaching 14.3 mag/square arc sec in the broadband K _s filter. The image quality of the camera + telescope was excellent, being seeing limited in the range 0.5–0.9.The science demonstration observations of the NIRC on the Keck Telescope included observations of the most distant galaxy known, 4C41.17 at a redshift z=3.8 and the most luminous object known, the IRAS source FSC10214+4724 at a redshift z=2.29. Observations of the radio galaxy address the problem of the alignment effect in high redshift radio galaxies as well as the environments of such systems. FSC10214+4724 appears to be a merging galaxy that is at least 5×10⁸ years old.Based on observations obtained at the W.M.Keck Observatory, which is operated jointly by the California Institute of Technology and the University of CaliforniaThe W.M. Keck Observatory is operated as a scientific partnership between the California Institute of Technology and the University of California. It was made possible by the generous gift of the W.M. Keck foundation and the support of its president, Howard Keck.     

The development of radio astronomy at Hartebeesthoek

The development of radio astronomy at the Hartebeesthoek Radio Astronomy Observatory in South Africa is described. The Hartebeesthoek site was established originally by NASA as one of three Deep Space Stations equipped with 26-m parabolic reflector antennas. It was first used for radio astronomy by South Africa in terms of the NASA host nation agreement which allowed for its use at times when the facility was not needed for its primary purpose of tracking space probes. After NASA withdrew from South Africa in 1975, the South African Council for Scientific and Industrial Research took over the site and the 26-m parabolic reflector antenna, which NASA had abandoned in position, and established it as a national observatory. The development of the facility to the stage where it could support a variety of observing programmes such as continuum observations and mapping, spectroscopy and pulsar timing is described as well as the role played by the Observatory in global programmes of very long baseline interferometry.