We have used three large-scale radio surveys to study the spectral behaviour of radio sources towards Abell clusters of galaxies. Without attempting to separate genuine cluster sources from background sources, we find a steeper median spectral index within 0.5 Abell radii (r_A_) than between 0.5 and 1 r_A_ (1 r_A_=3 h_50^-1 Mpc, and H_0 = 50 h_50_

In this paper we present a high resolution IR spectrum of the planetary nebula Hb5, over the range 1.6-1.75 micron. Our aim is to test the hypothesis invoking emission from upper vibrational levels in excited PAH molecules and anharmonicity of the C-H stretching mode to explain the weak features observed in the 3 micron range. The predicted first

On the basis of a large amount of high-precision photoelectric photometric data obtained at three sites and by use of the method of Fourier period analysis, the multiple frequencies of HD 213534 have been obtained. Five frequencies have been definitely detected. After an analysis of the star's pulsation modes, it is concluded that it is a multiple

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Spectropolarimetric observations of the quasar 3C 273 over the range 3200-8000 A show wavelength-dependent polarization in the continuum, while the lines had no detectable polarization. The total polarization at the red end spectrum was near 2.5 percent, the highest ever measured for 3C 273. No wavelength dependence of the polarized flux is

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