... Despite new observation methods provided by radar and satellite instrumentation , optical measurements are still important when studying auroras . ... Because of the monochromatic nature of the auroral light, photomultiplier tubes with very narrow band filters were used in the measurements. ... The spectra of the background emissions from atmospheric impurities (clouds, ice crystals, etc.) is rather continuous, and measurements just outside the auroral emission lines are valid for the line itself. ...

... title='Мышь проводная Dialog Pointer Optical MOP-04BU' border='0' align='left' width='120' style='margin-right: 20px;' hspace='7' vspace='5'/> . ... Платье Love & Light. ... Платье - Laura Bettini - Laura Bettini . ...

RTT150 . Russian-Turkish 1.5-m Telescope . ... Telescope has two main foci (Cassegrain and Coude ) and allows to use six optical systems based on Ritchey-Chretien system with a common main mirror . At present scientific observations are being performed at the Cassegrain focus in main optical scheme with focal ratio of 1:7.7. ... flat . ... To use the Coude focus the removable flat diagonal mirror is also needed in the crossing point of declination axis and main optical axis of telescope. ...

Static Fourier spectrometers are often used for spectral measurements of the ionosphere emissions. There are two main advantages of Fourier spectrometers (FS) - large geometric factor and high spectral resolution; these parameters are two orders better than for grating spectral instruments. ... In scanning Fourier spectrometer optical and electric modulation of signal is used to avoid this problem, for static Fourier spectrometer there are no such ways. ...

Peremennye Zvezdy", . ... We present the historical light curve of NGC 4151 for 1906 - 2007. The light curve is primarily based on our published photoelectric data (1968 - 2007, about 1040 nightly mean measurements) and photographic estimates (mostly Odessa and Moscow plates taken in 1906 - 1982, about 350 measurements; Oknyanskij 1977, 1978, 1983). ... 1983) (Harvard and Steward observatories' patrol plates taken in 1910 - 1968, about 210 measurements). ... Light Curve . ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... The light curves of AM CVn systems obtained using the Liverpool Telescope which showed an outburst. We show the start date of the observations in the top right of each panel and the orbital period of each system towards the right. ... The orbital period of the outbursting systems lie in the range 24тАУ44 mins and is remarkably consistent with disk-instability predictions. ... Systems which have short periods ( . ...