Multiple periodic oscillations in the radio light curves of NRAO 530
  In this paper, the time series analysis method CLEANest is employed to search
for characteristic periodicities in the radio light curves of the blazar NRAO
530 at 4.8, 8.0 and 14.5 GHz over a time baseline of three decades. Two
prominent periodicities on time scales of about 6.3 and 9.5 yr are identified
at all three frequencies, in agreement with previous results derived from
different numerical techniques, confirming the multiplicity of the
periodicities in NRAO 530. In addition to these two significant periods, there
is also evidence of shorter-timescale periodicities of about 5.0 yr, 4.2 yr,
3.4 yr and 2.8 yr showing lower amplitude in the periodograms. The physical
mechanisms responsible for the radio quasi-periodic oscillations and the
multiplicity of the periods are discussed.
