  Temporal variation of secondary cosmic rays (SCR) flux was measured during
the total lunar eclipse on December 10, 2011 and the subsequent full moon on
January 8, 2012. The measurements were done at Department of Physics,
University of Mumbai, Mumbai (Geomagnetic latitude: 10.6 N), India using NaI
(Tl) scintillation detector by keeping energy threshold of 200 KeV. The SCR
flux showed approximately 8.1% enhancement during the lunar eclipse as compared
to the average of pre- and post-eclipse periods. Weather parameters
(temperature and relative humidity) were continuously monitored and their
correlations with temporal variation in SCR flux were examined. The influences
of geomagnetic field, interplanetary parameters and tidal effect on SCR flux
were considered. Qualitative analysis of SCR flux variation indicates that the
known factors affecting SCR flux fail to explain observed enhancement during
the eclipse. This enhancement during lunar eclipse and widely reported decrease
during solar eclipses may unravel hitherto unnoticed factors modulating SCR
flux.
