Simultaneous B′V′R′ monitoring of bl lacertae object S5 0716+714 and detection of inter-band time delay

We present the results of our optical monitoring of the BL Lac object S5 0716+714 over seven nights in 2006 December. The monitoring was carried out simultaneously at three optical wavelengths with a novel photometric system. The object did not show large-amplitude internight variations during this period. Intranight variations were observed on four nights and probably on one more. Strong bluer-when-brighter chromatism was detected on both intranight and internight timescales. The intranight variation amplitude decreases in the wavelength sequence of B′, R′, and V′. Cross-correlation analyses revealed that the variability at the B′ and V′ bands leads that at the R′ band by about 30minutes on one night. © 2012. The American Astronomical Society. All rights reserved.