The Spectrum-UV Mission: an International Ultraviolet Observatory

The Spectrum-UV Mission is an ultraviolet space observatory, scheduled to be launched at the break of the century into a 7-day, highly excentric orbit aboard a Spectrum Series platform. The Observatory is endowed with a 170-cm aperture telescope and a focal plane instrument complement for spectroscopy and imaging in the 912 to 3600 range. The results of an advanced feasibility study, being carried out in the four partecipating Countries (Germany, Italy, Russia and Ukraine) are presented.     

IR array instruments for the ESO VLT

The four infrared instruments currently planned for the ESO VLT are briefly described and their collective infrared array requirements are summarized and discussed in the light of recent advances in this area.     

A window on the plasma universe: the very large array

For nearly two decades, the aperature synthesis telescope known as the Very Large Array (VLA) has been providing a wealth of data on all types of astronomical objects. This telescope fills the need for more powerful and more sensitive instruments to gather data on a vast range of plasma phenomena in astrophysical settings. Currently the VLA is capable of observing at eight radio frequency bands (four corresponding to important spectral lines) with sensitivities on the order of 10^–29 Wm ^–2 Hz ^–1, or 10^–3 Jansky (1 mJy), and noise levels ten times lower. This paper describes the VLA and its capabilities, and describes how researchers interested in plasma astrophysics can use the instrument.     

The NASA-ARC 10/20 micron camera

A new infrared camera (AIR Camera) has been developed at NASA-Ames Research Center for observations from ground-based telescopes. The heart of the camera is a Hughes 58 × 62 pixel Arsenic-doped Silicon detector array that has the spectral sensitivity range to allow observations in both the 10 and 20 micron atmospheric windows.The U.S. Government right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

Dichroic Filters For Astronomical X-Ray Polarimetry

We describe a programme of research to investigate materials which exhibit linear dichroism at X-ray wavelengths, and to assess their potential as astronomical X-ray polarimeters. The availability of polarising filters for X-rays would offer an efficient method of quantifying the polarisation of X-ray radiation from distant, cosmic sources. A polarising dichroic filter is expected to be a compact, low mass device which could add polarimetry capability to an instrument by being introduced into the optical path ahead of a detector. We provide estimates of sensitivity in the context of the proposed XEUS observatory, which compare favourably with those for the most promising alternative technology. We also discuss a number of astrophysical sources which are suited to polarimetric study at discrete energies offered by the X-ray dichroic filter design.     

The High Resolution Chirp Transform Spectrometer for the Sofia-Great Instrument

In this paper, we present the design of a high resolution Chirp Transform Spectrometer (CTS) which is part of the GREAT (German REceiver for Astronomy at Terahertz frequencies) instrument onboard SOFIA, the Stratospheric Observatory For Infrared Astronomy. The new spectrometer will provide unique spectral resolving power and linearity response, since the analog Fourier transform performed by the CTS spectrometer was improved through a new design, that we call “Adaptive Digital Chirp Processor (ADCP)”. The principle behind the ADCP consists on digitally generating the dispersive signal which adapts to the compressor dispersive properties, achieving maximum spectral resolution and higher dynamic range. Excellent test results have been obtained such as a white noise dynamic range of 30 dB, and a spectral resolution (FWHM) of 41.68 kHz which would mean if analyzing signals with the high frequency band receiver on the GREAT instrument (4.7 THz) a spectral resolving power (λ/Δ λ) higher than 10⁸.     

Hard X-ray imaging via focusing optics with mosaic crystals

In spite of the tremendous potential of hard X-ray astronomy (>10 keV) for studying high energy phenomena in celestial objects, the current generation of direct-viewing telescopes is heavily noise limited. It can accurately study only the strongest sources. Thus focusing of hard X-rays is mandatory in order to overcome these sensitivity limitations. Several focusing techniques of hard X-rays (>10 keV) are under study. We will discuss the Bragg diffraction technique and the imaging performance of a concentrator configuration based on this technique. Apart from its unprecedented flux sensitivity, the Bragg concentrators show intrinsic capabilities as polarimeters.     

TAUVEX - Tel Aviv University UV Explorer

TAUVEX - Tel Aviv University UV Explorer is a space telescope that is currently being built in Israel, to be flown on board the Russian international sattelite SRG - Spectrum Roentgen Gamma, in late 1995 or early 1996. TAUVEX is an imager in the near UV spectral window. Its major goal is to make a survey of about 10% of the UV sky, in the range = 1350 - 3500Å. A successful operation of TAUVEX will partially fill an important gap in our recognition of the sky, namely the distribution and the nature of the celestial UV sources, which are still mostly unknown. TAUVEX will also operate as a fast multicolor photometer in its UV range of operation. TAUVEX is aligned in parallel to the common optical axix of all the other instruments on board SRG, most of which are telescopes and monitors for high energy radiation. SRG will be thus able to perform for the first time in history simultaneous astronomical observations in one and the same celestial body, that cover together 7 order of magnitude of the recorded radiation. The observations of TAUVEX can be greatly enhanced by ground base observations.     

GALACSI – The ground layer adaptive optics system for MUSE

MUSE, the Multi-Unit Spectroscopic Explorer, is an adaptive optics (AO)-assisted Integral Field Spectrograph, currently in the Preliminary Design Phase as a second generation instrument for the VLT. MUSE will feature two modes, each with an associated AO mode. The first mode is the wide field mode, mainly aiming at the study of high redshift galaxies. For this mode, the AO system has to deliver an improvement of at least a factor of two over the full 1′ × 1′ field of view. The second mode, the narrow field mode, aims at the high-resolution spectroscopy of nearby extended objects, for example, galaxies and globular clusters. For this mode, the AO system will have to deliver near-diffraction limited performance over a small field of view. In this paper, we discuss the trade-offs in the current design of GALACSI – the MUSE AO system – and illustrate with a number of simulations the expected performance in the wide- and narrow field modes.     

Wide field monitoring of the X-ray sky using Rotation Modulation Collimators

Wide field monitoring is of particular interest in X-ray astronomy due to the strong time-variability of most X-ray sources. Not only does the time-profiles of the persistent sources contain characteristic signatures of the underlying physical systems, but, additionally, some of the most intriguing sources have long periods of quiesense in which they are almost undetectable as X-ray sources, interspersed with relatively brief periods of intense outbursts, where we have unique opportunities of studying dynamical effects, in, for instance, the evolution of accretion discs. Another question for which wide field monitors may provide key information, is the origin and nature of the cosmic gamma ray bursts.Rotation Modulation Collimators (RMC's) were originally introduced in X-ray astronomy to provide accurate source localizations over extended fields. This role has since been taken over by the grazing incidence telescope systems. The potential of the RMC's as wide field monitors have recently been demonstrated by the WATCH instruments on GRANAT and EURECA. It now appears likely, that for use on large, 3-axis stabilized spacecraft, a pinhole camera system may provide better sensitivity than an RMC-system of corresponding physical dimensions. But due to its simplicity, low data rate, and ability to work on spin stabilized (micro)satellites, the RMC wide field monitor may still have a role to play in the X-ray astronomy of the future.     

New aspects for new generation telescopes

A selection of future observing facilities relevant to galaxy evolution science covering the wavelength range from X-rays to the radio regime are summarized. Scientific aspects that can be investigated with these next generation telescopes are briefly discussed. While prospects look bright for highly advanced and innovative future facilities, it will be important to ensure that human resources in observational astronomy and theory – both in terms of expertise, funding, and available positions – are keeping pace with the technological developments. This revised version was published online in August 2006 with corrections to the Cover Date.     

紫金山天文台图书馆“国际交换”现状

科学技术突飞猛进的今天 ,天文学科也在迅速发展。为及时获得天文学科新成果的信息及动态 ,我馆采取采购 ,国际文献交换及接受赠品等途径来实现搜集文献任务。图书馆大部分经费用于采购。由于当前经费短缺 ,书刊采购受到限制。受赠只是单方面的 ,时有时无。紫台有 6 0多年历史 ,历任紫台领导和广大研究人员又对国际交换的关心和重视 ,国际交换优势更为明显。现将紫台图书馆国际交换现状列述如下     

Instrumentation for very high energy gamma-ray astronomy

Considerable progress has been made in the last half-decade in the field of very high energy (VHE) gamma-ray astronomy (photons with energies between 10¹¹ and 10¹³ eV). The high background level due to the isotropic cosmic ray flux which has bedevilled the field since its inception in the early 1960's can now be reduced to such a degree that significant gamma-ray signals from several sources become visible within a few hours of observation. The instrumentation and methodologies which have made this possible are reviewed. A brief historical introduction is followed by a summary of the salient properties of the atmospheric Cherenkov flash associated with VHE gamma-ray events. The major components of a VHE gamma-ray astronomy telescope are then reviewed. This is followed by a discussion of the different methodologies currently being used to discriminate against the cosmic ray background. Properties of several specific installations are then summarized, and possible future developments in VHE instrumentation are briefly discussed.     

Palomar prime-focus infrared camera (PFIRCAM)

In a joint effort between engineers and scientists at the Jet Propulsion Laboratory and the California Institute of Technology, a near-infrared (0.8–2.6 m) direct imaging system has been developed and integrated into the Caltech Palomar Observatory detector series. The camera system has been tested and operated in a science mode at the prime-focus (f/3.3) of the Hale 5-m Telescope. This paper outlines the system components and performance, including discussion of the detector linearity.     

毫秒脉冲量计时方法的研究进展和前景

介绍脉冲星的时间频率特征,脉冲星时间研究的意义,毫秒脉冲星计时理论方法和技术方面的研究进展,对其中的关键问题给予讨论．并对其发展前景进行了展望．