南方基地知识库

黑洞暂现双星MAXI J1820+070于2018年3月的明亮爆发为研究光学快速测光能力提供了重要机遇.以快速光学相机（Fast Optical Camera,FOC）为终端设备分别在2018年4月22日、5月26日和8月31日（UTC）使用云南天文台丽江观测站2.4 m望远镜对爆发中的黑洞双星MAXI J1820+070进行了亚秒时标的测光观测.通过观测数据分析,研究了相机的快速测光性能.对全帧和1/4帧两种观测模式的帧间间隔（frame time）,测得平均帧间间隔为（22.866±0.679） ms和（5.868±0.169） ms.通过视场中多颗明亮参考源校准,提取了观测对象和参考源的光变曲线,获得了光变曲线的傅里叶功率谱,区分了观测对象本征光变和仪器或望远镜等观测因素带来的非本征光变,成功探测到目标黑洞双星MAXI J1820+070中的光学波段低频准周期振荡信号,并判别了观测中来自仪器设备或与观测条件相关的时变信号.这成功验证了相机高速稳定的测光性能和对短至5 ms时标光变信号的探测能力.

We performed the high-speed photometric observation of the black hole transient MAXI J1820+070 on April 22, May 26, and August 31, 2018 (UTC) with our Fast Optical Camera (FOC) installed on the Lijiang 2. 4 m telescope at Lijiang Station of Yunnan Observatories. We analyzed the frame time of the FOC, obtained the light curves and power spectra of the target and several comparison stars in the same field of view to investigate the photometric performance of FOC. The frame time corresponding to the full-frame and 1/4-frame CCD (Charge Coupled Device) modes reached (22. 866 ± 0. 679) milliseconds and (5. 868 ± 0. 169) milliseconds, respectively. We use the average light curve of several comparison stars to calibrate the raw light curves of the black hole transient MAXI J1820+070 to obtain the calibrated light curves of the target in which the influence of variable weather conditions and instrumental effects have been mostly eliminated. By comparing and analyzing the original and calibrated power spectra of MAXI J1820+070 and those of the comparison stars, we detected an optical quasi-periodic oscillation (QPO) at 0. 16 Hz in the black hole transient MAXI J1820+070 in April 2018 and identified a few instrumental or atmospheric timing signals in the observations. This demonstrates the capability of our FOC in associating with the Lijiang 2. 4 m telescope for high-speed photometry.