The EUV spectrum of the Sun: long-term variations in the SOHO CDS NIS spectral responsivities
The EUV spectrum of the Sun: long-term variations in the SOHO CDS NIS spectral responsivities
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太阳的 EUV 光谱：SOHO CDS NIS 光谱响应度的长期变化
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
W. Thompson
中科院分区：
文献类型：
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作者：
G. Zanna;V. Andretta;P. Chamberlin;T. Woods;W. Thompson
我们展示了 SOHO 日冕诊断光谱仪 (CDS) 从 1996 年任务开始至今拍摄的太阳正入射、极紫外光谱。我们使用各种方法来研究仪器在如此长的时间跨度内的性能。假设太阳安静部分的基础色球过渡区域发射在整个周期内没有变化，我们发现仪器灵敏度随着时间的推移缓慢下降。我们对 NIS（正态入射光谱仪）数据进行了校正，使用从 1997 年 5 月的火箭飞行比较中获得的 NIS 绝对校准作为起始参考。然后，我们从 2008 年的观测中获得了 NIS 全太阳光谱辐照度，并将它们与从 2008 年 4 月 14 日飞行的太阳动力学观测站 EVE 仪器原型火箭获得的 EUV 辐照度进行了比较。 NIS 和 EVE 原型的 EUV 辐照度之间存在极好的一致性，证实了 NIS 辐射校准。 13 年来，NIS 仪器一直表现出色，大多数波长的响应度仅下降约 2 倍。
We present SOHO Coronal Diagnostic Spectrometer (CDS) normal incidence, extreme-ultraviolet spectra of the Sun taken from the beginning of the mission in 1996 until now. We use various methods to study the performance of the instrument during such a long time span. Assuming that the basal chromospheric-transition region emission in the quiet parts of the Sun does not vary over the cycle, we find a slow decrease in the instrument sensitivity over time. We applied a correction to the NIS (Normal Incidence Spectrograph) data, using as a starting reference the NIS absolute calibration obtained from a comparison with a rocket flight in May 1997. We then obtained NIS full-Sun spectral irradiances from observations in 2008 and compared them with the EUV irradiances obtained from the rocket that flew on April 14, 2008 a prototype of the Solar Dynamics Observatory EVE instrument. Excellent agreement is found between the EUV irradiances from NIS and from the EVE-prototype, confirming the NIS radiometric calibration. The NIS instrument over 13 years has performed exceptionally well, with only a factor of about 2 decrease in responsivity for most wavelengths.