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arXiv 1906.04060astro-ph.IMastro-ph.EP
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CAFE2:CAFE高分辨率摄谱仪的升级版。调试结果和新的公共管道

CAFE2: an upgrade to the CAFE high-resolution spectrograph. Commissioning results and new public pipeline

J. Lillo-Box, J. Aceituno, S. Pedraz, G. Bergond, D. Galadí-Enríquez, M. Azzaro, B. Arroyo-Torres, A. Fernández-Martín, A. Guijarro, R. P. Hedrosa, I. Hermelo, … 展开作者

J. Lillo-Box, J. Aceituno, S. Pedraz, G. Bergond, D. Galadí-Enríquez, M. Azzaro, B. Arroyo-Torres, A. Fernández-Martín, A. Guijarro, R. P. Hedrosa, I. Hermelo, F. Hoyo, P. Martín-Fernández

摘要:

卡拉尔阿尔托光纤馈入的埃歇尔摄谱仪(CAFE)是一台高分辨率摄谱仪,安装在卡拉尔阿尔托天文台的2.2米望远镜上,具有高精度径向速度能力。经过4年的运营,它遭受了严重的退化,现在已经升级。该仪器的升级(现命名为CAFE $_2$)旨在提高通量和稳定性,这要归功于新的光栅、隔离Coudé室中的主动温度控制以及新的加扰系统等微小变化。在本文中,我们提出了重新调试的仪器和一个新的管道(CAFExtractor),为用户提供充分减少的数据,包括径向速度测量FGK矮星的结果。我们已经对升级后的仪器进行了数月的监测,以表征其主要性能并测试新管道。它使用CERES代码的一部分,改进了波长校准和径向速度提取(使用HARPS掩模调整),应用夜间漂移校正。最终简化的光谱在FITS文件中呈现。调试结果表明,相对于干预前的降级状态,仪器性能有了明显改善。现在,室温在一个晚上稳定在5 mK以下,在两个月内稳定在50 mK以下。CAFE $_2$现在在参考ThAr框架上提供3 m/s的精度,天空测试在一个晚上提供8 m/s的径向速度精度(S/N>50)。仪器的通量现在恢复到标称值,在550 nm处的效率约为15%。仪器在1小时曝光和S/N=20时的极限星等为V=15。CAFE $_2$具有所有这些特性,因此进入了安装在2-4米级望远镜上的高分辨率摄谱仪的小家族,能够达到10米/秒以下的径向速度精度。

英文摘要:

The Calar Alto Fiber-fed Échelle spectrograph (CAFE) is a high-resolution spectrographs with high-precision radial velocity capabilities mounted in the 2.2m telescope of Calar Alto Observatory. It suffered from strong degradation after 4 years of operations and it has now been upgraded. The upgrades of the instrument (now named CAFE$_2$) aimed at improving the throughput and stability thanks to the inclusion of a new grating, an active temperature control in the isolated coudé room, and a new scrambling system among other minor changes. In this paper, we present the results of the re-commissioning of the instrument and a new pipeline (CAFExtractor) that provides the user with fully reduced data including radial velocity measurements of FGK dwarf stars. We have monitored the upgraded instrument for several months to characterize its main properties and test the new pipeline. It uses part of the CERES code, improves the wavelength calibration and radial velocity extraction (using the HARPS masks adapted), applies nightly drift corrections. The finally reduced spectra are presented in FITS files. The commissioning results show a clear improvement in the instrument performance with respect to the degraded status before the intervention. The room temperature is now stabilized down to 5 mK during one night and below 50 mK over two months. CAFE$_2$ now provides 3 m/s precision on the reference ThAr frames and the on-sky tests provide a radial velocity precision of 8 m/s during one night (for S/N>50). The throughput of the instrument is now back to nominal values with an efficiency of around 15% at 550 nm. The limiting magnitude of the instrument for a 1h exposure and S/N=20 is V=15. With all these properties, CAFE$_2$ enters into the small family of high-resolution spectrographs mounted on 2-4 meter-class telescopes capable of reaching radial velocity precisions below 10 m/s.

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