| Active Galactic Nucleus(AGNs) is the hottest research on modern astrophysics. Blazars are one of the most extreme classes of active galactic nucleus, with high luminosity, large amplitude and rapid variability, high and variable polarization, radio core-dominance, and apparent superluminal speeds. Their broad band emission extends from radio up to γ-ray band, and dominated by non-thermal process. Due to special character of blazars, we can know the central region of the AGNs, and we can also know how does release the energy from the central black hole through researching on the blazers. It is significant that we understand how dose produce the energy, and what kind of jets nature make to develop the black hole. Variability is a important parameter, it is important for understanding inner physical structure and radiation mechanism of blazars. The paper systematically expatiate on the observation character, the spectral energy distributions, the theoretical radiation model, the short timescales, middle timescales, and long-term variability, CCD photometry and atmospheric extinction calculus. We compiled short timescales variability of 48 blazars from the available literature, and calculated the mass of the central black hole and different band emission region of blazars. Base on our results of statistical analysis, we conclude that the mass of the flat spectral radio quasistellar is large than the mass of the BL Lac object, the v -ray and infrared emission regions are cospatial, and γ -ray emission region far from the optical and X-ray emission regions. Furthermore , in the process of CCD photometry observation, we carried our study with 1. 02m telescope of Yunnan observatory to BL Lac object MRK 501 in different integration time, and obtained the relation between error of photometric and integration time in the R band in the I band. Our results indicate that when the integration time in the I band more than integration time in the R band, the photometry error is minimum value. |
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