  We present the results of searches for anisotropy in the right ascension
($RA$) distribution of arrival directions of cosmic rays (CRs) detected with
the Yakutsk array during the 1974--2008 observational period in the energy
range above $10^{18}$ eV. Two methods of analysis are applied to two
sub-samples of the data. Particularly, estimations of the first and second
harmonic amplitudes are given, as well as the first harmonic phase in adjacent
energy intervals. Analysis of variance demonstrates a significant contraction
of the minimal width of the $RA$ distribution in the energy bin
$(10^{19},1.78\times10^{19})$ eV with respect to the isotropic distribution,
which may be attributed to a possible source of CRs within the interval
$RA\in(15^0,45^0)$.
