[Dai, B. Z.
; Li, X. H.
; Liu, Z. M.
; Wu, Y. F.
; Hao, J. M.
; Xiang, Y.
; Jiang, Z. J.
; Zhang, L.] Yunnan Univ, Dept Phys, Kunming 650091, Peoples R China
; [Zhang, B. K.] Chinese Acad Sci, Inst High Energy Phys, Lab Particle Astrophys, Beijing 10039, Peoples R China
; [Na, W. W.] Yuxi Normal Coll, Dept Phys, Yuxi 653100, Peoples R China
; [Hao, J. M.] Yunnan Normal Univ, Kunming 650091, Peoples R China
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.
Dai, BZ,Li, XH,Liu, ZM,et al. The long-term multiband optical observations and colour index for the quasar 3C 273[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2009,392(3):1181-1192.
Dai, BZ.,Li, XH.,Liu, ZM.,Zhang, BK.,Na, WW.,...&张丙开.(2009).The long-term multiband optical observations and colour index for the quasar 3C 273.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,392(3),1181-1192.
Dai, BZ,et al."The long-term multiband optical observations and colour index for the quasar 3C 273".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 392.3(2009):1181-1192.