A strong emission line at 6703Åhas been detected in the optical spectrum for the host galaxy (R=23.1) of the radio source RC J0311+0507 (4C+04.11). This radio galaxy, with a spectral index of 1.31 in the frequency range 365-4850 MHz, is one of the ultrasteep spectrum objects from the deep survey of a sky strip conducted with RATAN-600 in 1980RATAN-600 in -1981 We present arguments in favor of the identification of this line with Lyα at redshift z = 4.514. In this case, the object belongs to the group of extremely distant radio galaxies of ultrahigh radio luminosity (P 1400 = 1.3 × 10 29 W Hz −1 ). Such power can be provided only by a fairly massive black hole (∼ 10 9 M ⊙ ) that formed in a time less than the age of the Universe at the observed z (1.3 Gyr) or had a primordial origin.

In this study we attempt to assess the possibility of detection of variable sources using the data of the 7.6-cm wavelength surveys carried out on the RATAN-600 radio telescope in the period from 1980 through 1994. Objects selected according to certain criteria from the RCR catalog are used to construct the calibration curves and to estimate the accuracy of the resulting calibration curves and determine the r.m.s. errors for the measured source flux densities. To check the calibration sources for the presence of variable objects, quantitative estimates are performed for a number of parameters that characterize variability, in particular, for the long-term variability index V and the χ 2 (chi-square) probability p. The long-term variability index was found to be positive for 14 out of approximately 80 calibration sources, possibly indicating that these sources are variable. The most likely candidate variables are the three sources with the χ 2 probability p > 0.95. Five sources have χ 2 probabilities in the 0.85 < p < 0.95 interval, and the remaining six in the 0.6 < p < 0.8 interval.Nine out of 14 objects are possibly variable in the optical range. The light curves and spectra are determined for possible variable sources and a number of "non-variable" objects. We plan to use the results of this study in our future searches for variable radio sources using the data of the "Cold" surveys.

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