We have monitored the BL Lac object S5 0716+714 in five intermediate optical wavebands from 2004 September to 2011 April. Here we present the data that include 8661 measurements. It represents one of the largest databases obtained for an object at optical domain. A simple analysis of the data indicates that the object was active in most time, and intraday variability was frequently observed. In total, the object varied by 2.614 magnitudes in the i band. Strong bluer-when-brighter chromatism was observed on long, intermediate, and short timescales.

We monitored BL Lacertae simultaneously in the optical B, V, R and I bands for 13 nights during the period 2012-2016. The variations were well correlated in all bands and the source showed significant intraday variability (IDV). We also studied its optical flux and colour behaviour, and searched for inter-band time lags. A strong bluer-whenbrighter chromatism was found on the intra-night time-scale. The spectral changes are not sensitive to the host galaxy contribution. Cross-correlation analysis revealed possible time delay of about 10 min between variations in the V and R bands. We interpreted the observed flares in terms of the model consisting of individual synchrotron pulses.

This paper aims to study the color behavior of the BL Lac object OJ 287 during optical outburst. According to the revisit of the data from the OJ-94 monitoring project and the analysis the data obtained with the 60/90 cm Schmidt Telescope of NAOC, we found a bluer-when-brighter chromatism in this object.The amplitude of variation tends to decrease with the decrease of frequency.These results are consistent with the shock-in-jet model. We made some simulations and confirmed that both amplitude difference and time delay between variations at different wavelengths can result in the phenomenon of bluer-whenbrighter. Our observations confirmed that OJ 287 underwent a double-peaked outburst after about 12 years from 1996, which provides further evidence for the binary black hole model in this object.

Gamma-ray bursts (GRBs) have long been proposed as a complementary probe to type Ia supernovae (SNe Ia) and the cosmic microwave background to explore the expansion history of the high-redshift universe, mainly because they are bright enough to be detected at greater distances. Although they lack definite physical explanations, many empirical correlations between GRB isotropic energy or luminosity and some directly detectable spectral or temporal properties have been proposed to make GRBs standard candles. Since the observed GRB rate falls off rapidly at low redshifts, this thus prevents a cosmology independent calibration of these correlations. In order to avoid the circularity problem, SN Ia data are usually used to calibrate the luminosity relations of GRBs in the low redshift region (limited by the redshift range for SN Ia sample), and then they are extrapolate the luminosity relations to the high redshift region. This approach is based on the assumption of no redshift evolution for GRB luminosity relations. In this work, we suggest the use of a complete quasar sample in the redshift range of 0.5 < z < 5.5 to test such an assumption. We divided the quasar sample into several subsamples with different redshift bins, and used each subsample to calibrate the isotropic γ-ray equivalent energy of GRBs in relevant redshift bins. By fitting the newly calibrated data, we find strong evidence that the most commonly used Amati relation between spectral peak energy and isotropic-equivalent radiated energy shows no, or marginal, evolution with redshift. Indeed, at different redshifts, the coefficients in the Amati relation could have a maximum variation of 0.93% at different redshifts, and there could be no coincidence in the range of 1σ.