We have compiled all the available optical B band data on OJ287, between 1890 and 1991. Using this data we have found a period of 11.6 +/- 0.5 yr for the outbursts in OJ 287. This value is in good agreement with the period of 11.65 yr between outbursts and 11.05 yr between minima found previously by Sillanpaa et al. (1988), using V-band data. Based

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We are living a renaissance of radio survey work: the size of source catalogues published in the first two years of this decade exceeds that of the entire 1980s! The total number of published flux densities in mid-1992 is probably nearing ~700,000 and is estimated to grow by a factor of four by the end of the decade. The number of known optical

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