Multi-color optical monitoring of the BL Lacertae object S5 0716+714 during the 2012 outburst

Abstract

We have monitored the BL Lacertae object S5 0716+714 in the optical bands during 2012 January and February with long time spans on intraday timescales ($>$5 hr) and high time resolutions. During this monitoring period, the object shows violent flaring activity both in short and intraday timescales. The object has high value of duty cycle. The light curves detected as intraday variability (IDV) show variability of various shapes. The variability amplitude is from 12.81 per cent to 33.22 per cent, and the average value $19.92\pm 5.87$ per cent. The overall magnitude variabilities are $△B=1^{\mathrm{m}}.24$, $△V=1^{\mathrm{m}}.42$, $△R=1^{\mathrm{m}}.3$, $△I=1^{\mathrm{m}}.23$ respectively. During the observations, the average change rate is $<CR>=0.035\pm 0.009$ Mag/h during the ascent and $<CR>=0.035\pm 0.014$ Mag/h during the descent. However, different cases are found on certain nights. There are good inter-bands correlations but not significant time lags for intraday and short timescales. The results of the autocorrelation function show that the variability timescales range from 0.054 day to 0.134 day. Most of nights show bluer when brighter (BWB) chromatic trend; a weak redder with brighter (RWB) trend is found; a few nights show no correlations between magnitude and color index. The BWB trend appears in the short timescales. During the flare the spectral index exhibits a clockwise loop for inter-nights. A shock-in-jet model and the shock wave propagating along a helical path are likely to explain the variability and color index variability.

46 pages, 7 figures, 9 tables. Accepted for publication in AJ. arXiv admin note: text overlap with arXiv:1703.01645. text overlap with arXiv:1407.7615 by other authors

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Cited by in corpus (8)

• Multi-wavelength Intra-day Variability and Quasi-periodic Oscillation in Blazars
• Optical quasi-periodic oscillation of the BL Lacertae object S5 0716+714 during the faint state
• Multicolor Optical Monitoring of the Blazar S5 0716+714 from 2017 to 2019
• A geometrical interpretation for the properties of multiband optical variability of the blazar S5 0716+714
• Quasi-simultaneous Spectroscopic and Multi-band Photometric Observations of Blazar S5 0716+714 during 2018-2019
• Long-term multiband optical variability of S5 0716+714 blazar
• Investigating Optical Variability of the Blazar S5 0716+714 On Diverse Time-scales
• Optical Monitoring and Long-term Optical Spectral Variability of BL Lacertae Object S5 0716+714