Solar Physics

, 292:150 | Cite as

Precise Reduction of Solar Spectra Observed by the One-Meter New Vacuum Solar Telescope

  • Yunfang Cai
  • Zhi Xu
  • Zhenggang Li
  • Yongyuan Xiang
  • Yuchao Chen
  • Yu Fu
  • Kaifan Ji
Article

Abstract

We present a precise and complete procedure for processing spectral data observed by the one-meter New Vacuum Solar Telescope (NVST). The procedure is suitable for both sit-and-stare and raster-scan spectra. In this work, the geometric distortions of the spectra are first corrected for subsequent processes. Then, considering the temporal changes and the remnants of spectral lines in the flat-field, the original flat-field matrix is split into four independent components to ensure a high-precision flat-fielding correction, consisting of the continuum gradient matrix, slit non-uniform matrix, CCD dust matrix, and interference fringe matrix. Subsequently, the spectral line drifts and intensity fluctuations of the science data are further corrected. After precise reduction with this procedure, the measuring accuracies of the Doppler velocities for different spectral lines and of the oscillation curves of the chromosphere and photosphere are measured. The results show that the highest measuring accuracy of the Doppler velocity is within \(100~\mbox{m}\,\mbox{s}^{-1}\), which indicates that the characteristics of the photosphere and chromosphere can be studied cospatially and cotemporally with the reduced spectra of the NVST.

Keywords

Spectrum, visible Sunspots, velocity Velocity fields, photosphere 

Notes

Acknowledgements

We appreciate all the help from the colleagues in the NVST team. We are also grateful to the anonymous referee for their useful comments. Many thanks are due to Song Feng, Yanxiao Liu, and Huanwen Peng for their kind assistance and helpful comments on this manuscript. The FTS atlas used in this article was produced by the NSO/NOAO. This work is supported by the National Natural Science Foundation of China (NSFC) under grant numbers 11773072, 11573012 and 11473064.

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.

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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  1. 1.Yunnan ObservatoriesChinese Academy of SciencesKunmingChina
  2. 2.University of Chinese Academy of SciencesBeijingChina

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