Simultaneous MITSuME gRI monitoring of S5 0716+714
  We present results of our intra-night optical flux monitoring observations of
S5 0716+714 done simultaneously in gRI filters. The observations were done
using Multicolor Imaging Telescopes for Survey and Monstrous Explosions
(MITSuME) instrument on the 50 cm telescope at the Okayama Astrophysical
Observatory over 30 nights between 11 March 2008 and 8 May 2008. Of these 30
nights, 22 nights have continuous (without any break) observations with
duration ranging from 1 to 6 hours and hence were considered for intra-night
optical variability (INOV). In total we have 4888 datapoints which were
simultaneous in gR and I filters. Of the 22 nights considered for INOV, the
object showed flux variability on 19 nights with the amplitude of variability
in the I-band ranging from ~4% to ~55%. The duty cycle for INOV was thus found
to be 83%. No time lag between different bands was noticed on most of the
nights, except for 3 nights where the variation in g was found to lead that of
the I band by 0.3 to 1.5 hrs. On inter-night timescales, no lag was found
between g and I bands. On inter-night timescales as well as intra-night
timescales on most of the nights, the amplitude of variability was found to
increase toward shorter wavelengths. The flux variations in the different bands
were not achromatic, with the blazar tending to become bluer when brighter both
on inter-night and intra-night timescales; and this might be attributed to the
larger amplitude variation at shorter wavelengths. A clear periodic variation
of 3.3 hrs was found on 1 April 2008 and a hint for another possible periodic
variability of 4 hrs was found on 31 March 2008. During our 30 days of
observations over a 2 month period the source has varied with an amplitude of
variability as large as ~80%.
