The atmospheric coherence is a highly variable parameter depending upon the high velocity wind. The size of the atmospheric coherence length widely known as, Fried's parameter, ro, has been computed during night at the ...

The night time variation of the Fried's parameter, r lower script o is measured on 28-29 March 1991, at the Cassegrain focus of 2.34 m Vainu Bappu Telescope (VBT), at Vainu Bappu Observatory (VBO), Kavalur, India, using ...

An interferometer system for use at the 2.34 meter Vainu Bappu Telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur, to obtain speckle-grams of astronomical objects in the visible wavelength, has been ...

This article is a sort of sequel of the earlier extensive review by Saha (1991a) where emphasis was laid down on the ground based single aperture, as well as on the working long baseline optical interferometers (LBI) ...

CERTAIN hot stars, belonging to the Be class, may have an envelope of hydrogen gas, possibly in the form of a rotating disk or spheroidal shell. Other models involve elliptical rings or close binary systems where the Roche ...

In view of the importance of multiple aperture synthesis in optical astronomy, a computer simulation of the same is demonstrated. The fringe patterns obtained through the aperture mask of six and nine holes arranged ...

Optical stellar interferometers have demonstrated milliarcsecond resolution with few apertures spaced hundreds of metres apart. To obtain rich direct images, many apertures will be needed, for a better sampling of the ...

Speckle interferometric technique is employed to record a series of hundreds of short-exposure images of several close binary stars with sub-arc second separation through a narrow band filter at the Cassegrain focus of ...

The technique of speckle interferometry, used for compensating the blurring effects of the earth's atmosphere, is briefly outlined. The achievements of this technique by different groups in the world are listed. We then ...

We conducted a multiwavelength campaign in 2002 September-October, to observe SS 433. We used the Giant Meter Radio Telescope for radio observations, the Physical Research Laboratory Infrared Telescope at Mt Abu for infrared ...