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The intra-day Optical Monitoring of BL Lacerate Object 1ES 1218+304 at Its Highest X-ray Flux Level

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 نشر من قبل Si Sun
 تاريخ النشر 2021
  مجال البحث فيزياء
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We here report a monitor of the BL Lac object 1ES 1218+304 in both B- and R-bands by the GWAC-F60A telescope in eight nights, when it was triggerd to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups. Both ANOVA and $chi^2$-test enable us to clearly reveal an intra-day variability in optical wavelengths in seven out of the eight nights. A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights, which can be well explained by the shock-in-jet model. In addtion, a quasi-periodic oscilation phenomenon in both bands could be tentatively identified in the first night. A positive delay between the two bands has been revealed in three out of the eight nights, and a negative one in the other nights. The identfied minimum time delay enables us to estimate the $M_{mathrm{BH}}=2.8times10^7 rm M_{odot}$that is invalid.



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