2.4米望远镜高时间分辨率观测系统的研究

High time resolution astronomical observation has incomparable superiority for the short-term astronomical phenomenon, the time scale from second to millisecond even better, which can recover the original light signal profile accurately, research light source with complex features，Transient source and its transient phenomena precisely. High time resolution astronomical observation can also indirectly increase the spatial resolution, Keep high frequency information of the target source, reconstruct high resolution image of the ground telescope closed to diffraction limit. With the development of the astronomical observation technology and large telescopic equipment, high time resolution astronomical observation get more and more attention of astronomers. So enhance the high time resolution observation ability of 2.4m telescope has become increasingly urgent.. We plan to develop a high time resolution general observation system for 2.4m telescope, which has two kinds model：fast photometry and high resolution imaging，and can switch each other according to the observation demand at any time. The frame frequency of it is 670 Hz, and covers most of the astronomical observation of transient source and its transient phenomena. It can enrich 2.4m telescope ability of time domain astronomical observation, and as a general-purpose equipment opened to the astronomical community.

高时间分辨率天文观测对于研究短时标天文现象具有无可比拟的优越性，时间标度从秒-毫秒-甚至更短的时间量级，能够精确复原原始光变信号轮廓，用于开展复杂光变特征源、暂现源及其瞬变现象的高精度观测研究；高时间分辨率天文观测还能间接增加天文观测的空间分辨率，保留目标源的高频信息，重建出接近地基望远镜衍射极限的高分辨率图像。随着天文观测技术和大型望远设备的发展，高时间分辨率天文观测越来越受到天文学家的重视，因此增强2.4米望远镜的高时间分辨率观测能力变得日益紧迫。. 本项目拟为2.4米望远镜研制一套高时间分辨率通用天文观测系统，具有快速测光和高分辨成像两种观测模式，可根据观测需求，随时对观测模式进行切换，其帧图像采集频率最高可实现670Hz，涵盖了天文观测中大部分的暂现源及其瞬变现象，能极大地丰富2.4米望远镜时域天文观测功能，并将作为通用设备对天文界开放使用。

本项目为2.4米望远镜研制一套高时间分辨率通用天文观测系统，具有快速测光和高分辨成像两种观测模式，可根据观测需求，随时对观测模式进行切换。通过实际测试，系统在快速测光观测模式下，焦比为F/3，工作视场能够达到6.3’×6.3’，空间分辨率为0.37”；高分辨成像观测模式下，焦比为F/32，工作视场能够达到0.6’×0.6’，空间分辨率为0.035”；观测系统的针孔像80%能量集中在0.75”内，优于丽江天文观测站平均视宁度水平。按照实测结果、丽江站天光背景及CCD读出噪声等参数分别计算了两个通道不同波段暗夜和辉夜的极限星等，对于快速测光观测模式，当Seeing为1.5”，曝光时间为1s，信噪比为5时，极限星等约为V=21.2；对于高分辨成像观测模式，Seeing为1.5”，曝光时间为0.001s，信噪比为5时，极限星等约为V=12.2。高时间分辨率观测系统经过实验室测试和实际观测均得到满意的性能指标，能够开展高精度的快速测光和高分辨成像天文观测。该设备有望在2021年下半年开始作为2.4米望远镜常规设备对天文界开放使用，对开展快速时变天文目标观测、拓展2.4米望远镜时域天文观测功能、提高2.4米望远镜观测能力和弥补2.4米望远镜短时标通用天文观测仪器的空白具有重要的意义。