A New Method of Deriving Doppler Velocities for Solar Orbiter SPICE
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914320010444800 |
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| author | Plowman, J. E. Hassler, D. M. Molnar, M. E. Shrivastav, A. K. Varesano, T. Auchère, F. Fludra, A. Kucera, T. A. Wang, T. J. Zhu, Y. |
| author_facet | Plowman, J. E. Hassler, D. M. Molnar, M. E. Shrivastav, A. K. Varesano, T. Auchère, F. Fludra, A. Kucera, T. A. Wang, T. J. Zhu, Y. |
| contents | This paper presents a follow-up to previous work on correcting PSF-induced Doppler artifacts in observations by the SPICE spectrograph on Solar Orbiter. In a previous paper, we demonstrated correction of these artifacts in the $y-λ$ plane with PSF Regularization, treating the forward problem with a method based on large sparse matrix inversion. It has since been found that similar apparent artifacts are also present in the $x-λ$ direction, i.e., across adjacent slit positions. This is difficult (although not impossible) to correct with the previous matrix inversion method due to the time variation between slit positions. We have therefore devised a new method which addresses both $x-λ$ and $y-λ$ artifacts simultaneously by applying wavelength dependent shifts at each $x-y$ plane of the spectral cube. This paper demonstrates the SPICE data issue, describes the new method, and shows a comparison with the previous one. We explore the time variation of the correction parameters for the SPICE data and show a clear orbit dependence. The results of the method are significantly higher quality derived Doppler signals, which we estimate at less than $\sim$ 5 km/s uncertainty for brighter lines in the absence of other systematics. Furthermore, we show the new SPICE polar observation results as a demonstration. The correction codes are written in Python, publicly available on GitHub, and can be directly applied to SPICE level 2 datasets. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2508_09121 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A New Method of Deriving Doppler Velocities for Solar Orbiter SPICE Plowman, J. E. Hassler, D. M. Molnar, M. E. Shrivastav, A. K. Varesano, T. Auchère, F. Fludra, A. Kucera, T. A. Wang, T. J. Zhu, Y. Solar and Stellar Astrophysics Instrumentation and Methods for Astrophysics This paper presents a follow-up to previous work on correcting PSF-induced Doppler artifacts in observations by the SPICE spectrograph on Solar Orbiter. In a previous paper, we demonstrated correction of these artifacts in the $y-λ$ plane with PSF Regularization, treating the forward problem with a method based on large sparse matrix inversion. It has since been found that similar apparent artifacts are also present in the $x-λ$ direction, i.e., across adjacent slit positions. This is difficult (although not impossible) to correct with the previous matrix inversion method due to the time variation between slit positions. We have therefore devised a new method which addresses both $x-λ$ and $y-λ$ artifacts simultaneously by applying wavelength dependent shifts at each $x-y$ plane of the spectral cube. This paper demonstrates the SPICE data issue, describes the new method, and shows a comparison with the previous one. We explore the time variation of the correction parameters for the SPICE data and show a clear orbit dependence. The results of the method are significantly higher quality derived Doppler signals, which we estimate at less than $\sim$ 5 km/s uncertainty for brighter lines in the absence of other systematics. Furthermore, we show the new SPICE polar observation results as a demonstration. The correction codes are written in Python, publicly available on GitHub, and can be directly applied to SPICE level 2 datasets. |
| title | A New Method of Deriving Doppler Velocities for Solar Orbiter SPICE |
| topic | Solar and Stellar Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2508.09121 |