The long-term multiband optical observations and colour index for the quasar 3C 273
The long-term multiband optical observations and colour index for the quasar 3C 273
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DOI：
10.1111/j.1365-2966.2008.14137.x
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发表时间：
2009-01
影响因子：
4.8
通讯作者：
B. Dai;Xiang Li;Z. M. Liu;Bo Zhang;W. Na;Y. F. Wu;J. Hao;Y. Xiang;Zejun Jiang;Li Zhang-L
中科院分区：
文献类型：
--
作者：
B. Dai;Xiang Li;Z. M. Liu;Bo Zhang;W. Na;Y. F. Wu;J. Hao;Y. Xiang;Zejun Jiang;Li Zhang-L
介绍了blazar 3C 273的长基线同步多波段观测结果。从2003年1月到2005年4月，我们利用云南天文台（YAO）103 cm和上海天文台（SHAO）156 cm进行了758次光学多波段观测。在我们的观测活动中，平均颜色指数为B - V = 0.21，V-R = 0.26和R-I = 0.31。B、V、R和I的平均星等分别为12.895、12.698、12.441和12.139。源在观测活动中处于稳定状态。讨论了色指数与亮度的相关性。我们发现，B - V与B、V-R与V、R-I与R的相关性呈显著负相关，而B - V与V、V-R与R、R-I与I呈正相关。这些强相关性意味着当光源变亮时，光谱变得更蓝（更平），而当光源在日内和长期变化中消失时，光谱变得更红（更软）。3C 273的光谱演化趋势与BL Lac天体一致。
The long baseline simultaneous multiband (BVRI) observations of blazar 3C 273 are presented. We have made 758 optical multiband observations with the Yunnan Astronomical Observatory (YAO) 103 cm and Shanghai Astronomical Observatory (SHAO) 156 cm from 2003 January to 2005 April. In our observational campaign, the average colour indices are B - V = 0.21, V - R= 0.26 and R - I = 0.31. The mean magnitudes in B, V, R and I are 12.895, 12.698, 12.441 and 12.139, respectively. The source is in a steady state over observational campaign. The correlations between colour index and brightness are discussed. We find that the correlations of B - V versus B, V - R versus V and R - I versus R have significant negative correlation, while B - V versus V, V - R versus R and R - I versus I have positive correlation. These strong correlations imply that the spectrum becomes bluer (flatter) when the source becomes brighter, and redden (softer) when the source fades both in intraday and long-term variability. The spectral evolution trends of 3C 273 are consistent with those of BL Lac objects.