  The Moon apparently seems to have not appreciable effect in the geomagnetic
monthly period, but Keil (1839), Sabine (1853), Broun (1874) and many others
have shown a lunisolar daily variation. It is known that solar (S) and lunar
(L) variation have seasonal variations. Seasonal changes of S, particularly on
quiet days, have been studied in greater detail than the seasonal changes for
L. The purpose of this paper is to describe in more detail the effect of the
variation of L in the geomagnetic equator, in the absence of strong
perturbations selecting conveniently geomagnetic data of Huancayo observatory
(hourly mean) from January 1, 2008 to December 31, 2009, period which is longer
in range of minimum solar activity of the last 160 years (end of solar cycle 23
and start of solar cycle 24). The spectral analysis by wavelet and Fourier
allows us to identify the main contribution of S diurnal and semidiurnal
variations and its sidebands, besides the effect of the seasonal variation. In
order to observe the variation L is subtracted the variation S together with
its sidebands, allowing observed by Fourier spectral analysis and wavelet as
the main contributions to the variation L, similar effect were described by
Chapman and Miller (1940).
