Assessing Galaxy Limiting Magnitudes in Large Optical Surveys
Assessing Galaxy Limiting Magnitudes in Large Optical Surveys
复制标题
评估大型光学巡天中的星系极限星等
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Keisler
中科院分区：
文献类型：
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作者：
E. Rykoff;E. Rozo;R. Keisler
大规模结构测量需要准确且精确地了解测量深度（通常以极限星等的形式表示）作为天空位置的函数。迄今为止，大多数勘测仅计算在固定公制孔径内测量的点源极限震级。然而，这个量不适合描述星系的极限深度，这取决于巡天系统与星系形状和大小的详细相互作用。我们描述了一种直接估计大型光度测量极限星等的经验方法，并将其应用于 SDSS DR8 数据的 $sim10,000,mathrm{deg}^{2}$。结合 SDSS Stripe 82 和 CFHTLens 的更深层次成像，我们能够使用这些深度图来估计整个 BOSS DR8 勘测区域内任何点的位置相关星系检测完整性。我们表明，这些地图可用于构建适合对调查极限星等附近的星系的相关函数进行无偏估计的随机点。最后，我们以 HEALPix 格式提供 SDSS DR8 中星系的极限星等图，其中 NSIDE=2048。
Large scale structure measurements require accurate and precise knowledge of the survey depth --- typically expressed in the form of a limiting magnitude --- as a function of position on the sky. To date, most surveys only compute the point-source limiting magnitude measured within a fixed metric aperture. However, this quantity is ill suited to describe the limiting depth of galaxies, which depends on the detailed interplay of survey systematics with galaxy shapes and sizes. We describe an empirical method for directly estimating the limiting magnitude for large photometric surveys, and apply it to $sim10,000,mathrm{deg}^{2}$ of SDSS DR8 data. Combined with deeper imaging from SDSS Stripe 82 and CFHTLens, we are able to use these depth maps to estimate the location-dependent galaxy detection completeness at any point within the full BOSS DR8 survey region. We show that these maps can be used to construct random points suitable for unbiased estimation of correlation functions for galaxies near the survey limiting magnitude. Finally, we provide limiting magnitude maps for galaxies in SDSS DR8 in HEALPix format with NSIDE=2048.