ISSN:
1573-093X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Fluctuations in the angle-of-arrival of a luminous wavefront are investigated by placing a narrow slit over the image of the solar limb, and observing the entrance pupil through this diaphragm. Measurement of the standard deviation σ AA of these fluctuations, in a direction perpendicular to the solar limb, provides sufficient information to estimate an absolute parameter characterizing the seeing, i.e. Fried's parameter r 0 or the equivalent parameter ∫ L C N 2(h) dh which gives the integral, over an atmosphere thickness L which depends on the spatial and angular filterings performed by the slit, of the structure constant C N 2 characterizing fluctuations in the air's refractive index. Simultaneous estimations of σ AA 2 and ∫ L C N 2 (h) dh permit a linear relationship to be established between these two quantities. The result is interpreted theoretically by integration of the two-dimensional power spectrum for the angle-of-arrival fluctuations. The influence of filtering effects is discussed. Such a calibration can be performed for a given telescope and slit, enabling the system to be used as a seeing monitor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00151449
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