PHOTOMETRIC CALIBRATION OF THE ACS
PHOTOMETRIC CALIBRATION OF THE ACS
复制标题
ACS 的光度校准
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
R. Bohlin
中科院分区：
文献类型：
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作者：
R. Bohlin
标准WFC和HRC滤光片的绝对通量刻度是根据现有的分光光度标准星的约束观测结果导出的。值的包围能量（EE）的一个弧秒半径相对于一个无限大的孔径半径推导出热的恒星和EE相比，较冷的恒星。定义了五年ACS寿命的灵敏度退化，并在推导CCD探测器的修订量子效率（QE）曲线之前用于校正ACS光度法。F850 LP的WFC测光观测结果与F850 LP的测光结果一致，即WFC的QE曲线向9400 A方向逐渐减小。宽波段QE变化（WFC的最大值为2.3%）也包含在两台CCD相机的修订QE曲线中。平均过滤器传输的修订高达4%，需要使宽带和窄带测光与合成测光从主白色矮星（WD）的准确协议。剩余的WD和较冷的星星测光之间的不一致进行了讨论，但没有解决，因为目前的数据集的限制。在解决这些差异之前，应将基本WD绝对通量校准转移到F8-G 0冷却器类型，在7000- 10000 A范围内，不确定度至少为2%。对于比G冷的光谱类型，HST通量校准可能具有甚至更大的误差。
absolute flux calibration of the standard WFC and HRC filters is derived from the available constraining observations of spectrophotometric standard stars. Values for the encircled energy (EE) of one arcsec radius relative to an infinite aperture radius are derived for hot stars and compared to the EE for cooler stars. The sensitivity degradation for the five year ACS lifetime is defined and used to correct the ACS photometry before deriving revised quantum efficiency (QE) curves for the CCD detectors. F850LP observations of red stars with WFC are made consistent with F850LP photometry for hotter stars by decreasing the WFC QE curve longward of 9400A. Broad band QE changes with a maximum of 2.3% for WFC are also included in the revised QE curves for both CCD cameras. Revisions of the average filter transmissions of up to 4% are required to bring both broad and narrow band photometry into exact agreement with synthetic photometry from the primary white dwarf (WD) stars. The remaining inconsistencies between WD and cooler star photometry are discussed but not resolved because of the limitations of the present data set. Until these discrepancies are resolved, the transfer of the fundamental WD absolute flux calibration to cooler types of F8-G0 should be regarded as uncertain by at least 2% in the 7000-10000A range. HST flux calibrations for spectral types cooler than G may have even larger errors.