JHK observations of faint standard stars in the Mauna Kea Observatories near-infrared photometric system     

S. K. Leggett  M. J. Currie  W. P. Varricatt  T. G. Hawarden  A. J. Adamson  J. Buckle  T. Carroll  J. K. Davies  C. J. Davis  T. H. Kerr  O. P. Kuhn  M. S. Seigar  T. Wold 《Monthly notices of the Royal Astronomical Society》2006,373(2):781-792

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Model of optical turbulence profile at Cerro Pachón     

A. Tokovinin  T. Travouillon 《Monthly notices of the Royal Astronomical Society》2006,365(4):1235-1242

New measurements of optical turbulence profile at the Cerro Pachón observatory in Chile are analysed jointly with previously published data to model the variations of the intensity and thickness of the ground layer and free atmosphere under a variety of observing conditions. This work is motivated by the need to predict statistically the performance of ground-layer adaptice optics. We find that the ground-layer profile can be represented by a decaying exponent with a scale height of 20–40 m, increasing to 100 m under bad conditions. The zone from 6 to 500 m contributes typically about 61 per cent to the total integral, the latter causing a median seeing of 0.77 arcsec. Turbulence integrals in the ground layer and in free atmosphere vary independently of each other, in 50 per cent of cases they deviate by less than 1.8 times from their respective median values. The existence of periods with low turbulence in the free atmosphere and their importance for adaptive optics is stressed.  相似文献   

Solar apparent radius variability: a new statistical approach to astrolabe multisite observations     

C. Badache-Damiani  J. P. Rozelot 《Monthly notices of the Royal Astronomical Society》2006,369(1):83-88

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双波长卫星激光测距     

张忠萍  李人东  杨福民  扈荆夫 《天文学进展》2005,23(2):99-109

双波长卫星激光测距不必借助大气改正模型，利用双波长往返时间差就可以进行大气折射改正，采用皮秒级事件计时器等技术测量往返时间差，修正精度可以达到毫米量级，介绍了这一领域的研究进展、双波长大气改正的基本原理，分析了双波长激光测距的精度，最后对双波长卫星激光测距前景进行了展望。  相似文献   

Phasing segmented mirrors using defocused images at visible wavelengths     

A. Schumacher  N. Devaney 《Monthly notices of the Royal Astronomical Society》2006,366(2):537-546

Plans for future optical telescopes of diameter more than 10 m are based on segmented mirrors, made up of hundreds or even thousands of segments. A challenge for these telescopes is the alignment in piston (cophasing) where phase differences between individual segments have to be reduced to a small fraction of the observing wavelength in order to avoid degradation of image quality.
Based on the phase discontinuity sensing method used at the Keck telescopes to measure small piston errors using infrared wavelengths, we develop a new method that allows fast high-precision measurements of large piston errors even at visible wavelengths.  相似文献   

Offline, multidetector intensity interferometers – I. Theory     

Aviv Ofir  Erez N. Ribak 《Monthly notices of the Royal Astronomical Society》2006,368(4):1646-1651

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数字滤波技术在射电天文测量中的应用     

项英  张秀忠 《天文学进展》2004,22(2):95-103

随着数字技术的发展，数字信号处理芯片的速度越来越快，这为高速数字滤波的实时实现提供了可能。简要阐述了数字滤波的原理，并对两种数字滤波的实现方法进行了分析；给出了数字滤波较模拟滤波的优势；介绍了数字滤波在射电天文测量中的各种应用。  相似文献   

The origin of [Fe ii] emission in NGC 4151     

James E. H.Turner  JeremyAllington-Smith †  ScottChapman ‡  RobertContent  ChristineDone  RogerHaynes §  DavidLee ¶  SimonMorris &#; 《Monthly notices of the Royal Astronomical Society》2002,331(2):284-292

The centre of NGC 4151 has been observed in the J band with the SMIRFS integral field unit (IFU) on the UK Infrared Telescope. A map of [Fe  ii ] emission is derived, and compared with the distributions of the optical narrow-line region and radio jet. We conclude that, because the [Fe  ii ] emission is associated more closely with the visible narrow-line region than with the radio jet, it arises mainly through photoionization of gas by collimated X-rays from the Seyfert nucleus. The velocity field and strength with respect to Pa β are found to be consistent with this argument. The performance of the IFU is considered briefly, and techniques for observation and data analysis are discussed.  相似文献   

二维太阳光谱观测方法和技术     

叶式辉 《天文学进展》1997,15(1):36-43

经典的太阳光谱观测是一维的，它有很大的局限性。从５０年代起，天文工作者采用多种方法开展二维太阳光谱观测，已经研制出一系列仪器，建立完整的资料归算程序，取得优良成果。在二维观测资料的基础上，用理论方法推出深度分布，可以得出三维的立体图像，这会成为太阳研究的主要方法之一。  相似文献   

Kinematics from spectroscopy with a wide slit: detecting black holes in galaxy centres     

Witold Maciejewski  James Binney 《Monthly notices of the Royal Astronomical Society》2001,323(4):831-838

We consider long-slit emission-line spectra of galactic nuclei when the slit is wider than the instrumental point spread function, and the target has large velocity gradients. The finite width of the slit generates complex distributions of brightness at a given spatial point in the measured spectrum, which can be misinterpreted as coming from additional physically distinct nuclear components. We illustrate this phenomenon for the case of a thin disc in circular motion around a nuclear black hole (BH). We develop a new method for estimating the mass of the BH that exploits a feature in the spectrum at the outer edge of the BH's sphere of influence, and therefore gives higher sensitivity to BH detection than traditional methods. Moreover, with this method we can determine the BH mass and the inclination of the surrounding disc separately, whereas the traditional approach to BH estimation requires two long-slit spectra to be taken. We show that, with a given spectrograph, the detectability of a BH depends on the sense of rotation of the nuclear disc. We apply our method to estimate the BH mass in M84 from a publicly available spectrum, and recover a value four times lower than that published previously from the same data.  相似文献