Measurement of the turbulence in the free atmosphere above Mt. Maidanakстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Stellar scintillations were measured at Mt. Maidanak during 42 nights in 1998-1999 in order to estimate the contribution of the free atmosphere to the seeing. The atmosphere above 1-2 km provides a median seeing of 0.''39, which is about one-third of the total seeing (0.''70). The characteristic altitudes of turbulent layers are from 3 to 11 km above the summit, and the appearance of layers at altitudes of 3-4 km is accompanied by a degradation of the free-atmosphere seeing. The median isoplanatic angle is θ_0 = 2.''30 (λ=500 nm, at the zenith). This is the first time that such data have been obtained for Maidanak. The instruments used for these measurements—a modified four-channel photometer and a prototype of a double-aperture scintillation sensor—are described in detail. The data reduction was based on accurate corrections for photon-counting statistics and the use of theoretical weighting functions relating scintillation indices to the altitudes and intensities of turbulent layers. Simultaneous or quasi-simultaneous measurements of scintillation indices using apertures of different sizes having significantly different weighting functions enable estimation of the altitude and intensity of the equivalent turbulent layer. Despite the simplicity of this one-layer model, it provides fairly robust estimates of the integrated parameters of the real free atmosphere.