Cycle 27 COS NUV Spectroscopic Sensitivity Monitor
Cycle 27 COS NUV Spectroscopic Sensitivity Monitor
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Cycle 27 COS NUV 光谱灵敏度监测仪
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
B. James
中科院分区：
文献类型：
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作者：
W. Fischer;B. James
HST分光光度标准星的观测表明，COS NUV探测器具有依赖于时间的灵敏度（TDS），必须在通量校准中进行监测和解释。定期观测监测三种NUV光栅的灵敏度变化：G230L，G185M和G225M。由于第四个光栅G285M的灵敏度现在非常低，因此将其从常规监测程序中删除，并且不鼓励将其用于通用观察器（GO）程序。来自周期26 NUV TDS程序的结果表明，涂覆MgF2的G230L和G185M光栅表现出与很少或没有变化一致的趋势。另一方面，G225M光栅，这是裸铝，显示出一个显着的灵敏度下降-2.87% ± 0.18%年-1。在周期26期间发现，当前NUV TDSTAB高估了每个光栅的灵敏度损失率。因此，NUV通量被略微过度校正，其量随着时间的推移而增加，并且近年来变得与5%的精度规格不一致。正在努力纠正这一点。
Observations of HST spectrophotometric standard stars show that the COS NUV detector has a time-dependent sensitivity (TDS) that must be monitored and accounted for in flux calibration. Regular observations monitor the changes in sensitivity for three NUV gratings: G230L, G185M, and G225M. Because the sensitivity of the fourth grating, G285M, is now very low, it was removed from the routine monitoring program, and its use is discouraged for General Observer (GO) programs. Results from the Cycle 26 NUV TDS program show that the G230L and G185M gratings, which are coated in MgF2, exhibit trends consistent with little or no change. On the other hand, the G225M grating, which is bare aluminum, shows a significant sensitivity decline of −2.87% ± 0.18% yr−1. It was discovered during Cycle 26 that the current NUV TDSTAB overestimates the rate of sensitivity loss for each grating. NUV fluxes have therefore been slightly overcorrected by an amount that grows with time and have, in recent years, become inconsistent with the 5% accuracy specification. Work is underway to correct this.