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arXiv 2108.00699astro-ph.IM
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利用Cherenkov照相机中的星重建监测原型LST-1的指向

Monitoring the pointing of the prototype LST-1 using star reconstruction in the Cherenkov camera

L. Foffano, A. Carosi, M. Dalchenko, M. Heller, D. Della Volpe, T. Montaruli

摘要:

为即将到来的切伦科夫望远镜阵列(CTA)提出的第一个大型望远镜(LST-1)已于2019年在拉帕尔马开始运行。LST-1的大型结构-直径为23米的反射镜-对其变形进行了严格控制,这可能会影响指向精度和整体性能。根据CTA的规格,设想解决例如银河系源的精细结构,LST校准后的指向精度应优于14角秒。为了满足这一要求,望远镜指向精度的监测与两个专用的CCD相机位于碟中心。对它们的图像的分析使我们能够理清结构的不同系统变形。在这项工作中,我们研究了一种互补的方法,提供了可能性,以监测指向的望远镜在收购的天空数据。在正确地清除切伦科夫簇射中的事件后,将相机视场中成像的恒星的重建位置与它们在星表中的标称预期位置进行比较。这提供了对望远镜指向的直接测量,其可用于交叉检查其他方法,并作为对望远镜的光学特性和由弯曲模型应用的指向校正的实时监测。此外,该方法的优点在于不依赖于特定的硬件或专用观测。在这篇文章中,我们将说明这种分析,并显示基于LST-1的模拟结果。

英文摘要:

The first Large-Sized Telescope (LST-1) proposed for the forthcoming Cherenkov Telescope Array (CTA) has started to operate in 2019 in La Palma. The large structure of LST-1 - with a 23 m mirror dish diameter - imposes a strict control of its deformations that could affect the pointing accuracy and its overall performance. According to CTA specifications that are conceived to resolve e.g. the fine structure of galactic sources, the LST post-calibration pointing accuracy should be better than 14 arcseconds. To fulfill this requirement, the telescope pointing precision is monitored with two dedicated CCD cameras located at the dish center. The analysis of their images allows us to disentangle different systematic deformations of the structure. In this work, we investigate a complementary approach that offers the possibility to monitor the pointing of the telescope during the acquisition of sky data. After properly cleaning the events from the Cherenkov showers, the reconstructed positions of the stars imaged in the camera field of view are compared to their nominal expected positions in catalogues. This provides a direct measurement of the telescope pointing, that can be used to cross-check the other methods and as a real-time monitoring of the optical properties of the telescope and of the pointing corrections applied by the bending models. Additionally, this method benefits from not relying on specific hardware or dedicated observations. In this contribution we will illustrate this analysis and show results based on simulations of LST-1.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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