The HB Narrowband Comet Filters: Standard Stars and Calibrations
The HB Narrowband Comet Filters: Standard Stars and Calibrations
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HB 窄带彗星滤波器：标准恒星和校准
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
M. A’Hearn
中科院分区：
文献类型：
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作者：
T. Farnham;D. Schleicher;M. A’Hearn
摘要 我们介绍了一组新的窄带彗星滤波器的开发和校准结果，称为 HB 滤波器组，其设计和制造是为了取代老化的 IHW 滤波器。还提供了有关滤波器设计和制造的信息，包括用于决定最终波长和带通的推理。新过滤器设计用于测量五种不同的气体种类（OH、NH、CN、C2、C3）、两种离子（CO+、H2O+）和四个连续点。自 IHW 滤波器开发以来，对彗星光谱发射带扩展翼的更好理解被纳入新设计中，因此与以前的滤波器相比，来自不需要的物质的污染显着减少。此外，制造技术的进步带来了更方形的透射剖面、更高的峰值透射率以及更长使用寿命的紫外线滤光片。我们进行了必要的校准，以便将过滤器获得的数据转换为绝对通量，从而可以从气体种类中准确减去连续体。选择并观察通量标准和太阳模拟，并使用数据建立 HB 滤波器的星等系统。恒星测量还用于评估哪些太阳类似物最能代表太阳，并探索紫外光通量标准在光谱类型方面有何不同。开发了新的程序来解释 OH 过滤器中的非线性消光，以便可以对零空气质量进行适当的外推，并且开发了一种新的形式主义，可以解释两个（或更多）过滤器中的相互污染，以减少彗星观测。给出了相关方程和折减系数，以及如何应用它们的详细说明。我们还进行了一系列涉及可能影响滤波器传输曲线或气体种类中发射线分布的因素的测试，以确定这些影响如何传播到校准系数。结果表明，只有两个因素在超过几个百分点的水平上值得关注：f 比小于 f/4，以及少数单独的滤波器，其传输曲线与校准中使用的滤波器显着不同。
Abstract We present results concerning the development and calibration of a new set of narrowband comet filters, designated the HB filter set, which was designed and manufactured to replace aging IHW filters. Information is also presented about the design and manufacturing of the filters, including the reasoning that was used for deciding the final wavelengths and bandpasses. The new filters are designed to measure five different gas species (OH, NH, CN, C2, C3), two ions (CO+, H2O+), and four continuum points. An improved understanding of extended wings from emission bands in comet spectra, gained since the development of the IHW filters, was incorporated into the new design, so that contamination from undesired species is significantly reduced compared to previous filters. In addition, advances in manufacturing techniques lead to squarer transmission profiles, higher peak transmission and UV filters with longer lifetimes. We performed the necessary calibrations so that data obtained with the filters can be converted to absolute fluxes, allowing for, among other things, accurate subtraction of the continuum from the gas species. Flux standards and solar analogs were selected and observed, and the data were used to establish a magnitude system for the HB filters. The star measurements were also used to evaluate which solar analogs were best representatives of the Sun and to explore how the flux standards differed in the UV with respect to their spectral type. New procedures were developed to account for the non-linear extinction in the OH filter, so that proper extrapolations to zero airmass can be performed, and a new formalism, which can account for mutual contaminations in two (or more) filters, was developed for reducing comet observations. The relevant equations and reduction coefficients are given, along with detailed instructions on how to apply them. We also performed a series of tests involving factors that can affect either the filter transmission profiles or the distribution of the emission lines in the gas species to determine how these effects propagate through to the calibration coefficients. The results indicate that there are only two factors that are a concern at a level of more than a few percent: f-ratios smaller than f/4, and a few individual filters whose transmission profiles are significantly different from the filters used in the calibrations.