Pasachoff J M, Muzyka D F, Schierer J P
Appl Opt. 1976 Nov 1;15(11):2884-90. doi: 10.1364/AO.15.002884.
A rapid-scanning silicon vidicon spectrometer is described; its sensitivity extends from 300 nm to 1080 nm, where even at that wavelength it has enough sensitivity to allow observation under eclipse conditions of a pair of forbidden spectral lines from twelve-times ionized iron that are sensitive indicators of the electron density in the solar corona. Past observational work on these ir lines is reviewed, and our vidicon observations made during the 1973 total solar eclipse are discussed. The vidicon target, the scanning procedure, and the advantages of the spectrometer are described. At the 1973 eclipse, the 1074.7-nm line was detected and an upper limit set for the 1079.8-nm line at a height of 1.4 solar radii. The resultant limit to the ratio of intensities gives electron densities in agreement with those derived from other methods and is consistent with observations made at lower heights; this indicates that the only previous eclipse observation of the ratio at this height was contaminated by scattered light. Our 1973 eclipse observations were limited by the high ambient temperature of the vidicon, by the less-than-optimum match of the focal ratios of the telescope and spectrometer optics, and by problems with the pointing during totality. These difficulties can be overcome, and the silicon vidicon spectrometer will be useful in both eclipse and noneclipse solar observing to map the coronal ir spectrum and also to study the [Fe XIII] ir and interlocking uv lines.
本文描述了一种快速扫描硅视像管光谱仪；其灵敏度范围为300纳米至1080纳米，即使在该波长下，它也具有足够的灵敏度，能够在日食条件下观测到来自十二次电离铁的一对禁戒谱线，这些谱线是日冕中电子密度的灵敏指标。回顾了过去对这些红外谱线的观测工作，并讨论了我们在1973年日全食期间进行的视像管观测。描述了视像管靶、扫描程序以及该光谱仪的优点。在1973年日食期间，检测到了1074.7纳米的谱线，并在1.4个太阳半径的高度上为1079.8纳米的谱线设定了上限。由此得出的强度比限制给出的电子密度与从其他方法得出的结果一致，并且与在较低高度进行的观测结果相符；这表明之前在该高度对该比值进行的唯一一次日食观测受到了散射光的影响。我们1973年的日食观测受到视像管周围环境温度过高、望远镜和光谱仪光学系统的焦比匹配不理想以及全食期间指向问题的限制。这些困难是可以克服的，硅视像管光谱仪在日食和非日食太阳观测中都将有助于绘制日冕红外光谱，还可用于研究[Fe XIII]红外谱线和相互关联的紫外谱线。
