Second Data Release of the All-sky NOIRLab Source Catalog
Second Data Release of the All-sky NOIRLab Source Catalog
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DOI：
10.3847/1538-3881/abd6e1
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
D. Nidever;A. Dey;K. Fasbender;S. Juneau;A. Meisner;Joseph Wishart;A. Scott;Kyle Matt;R. Ni
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文献类型：
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作者：
D. Nidever;A. Dey;K. Fasbender;S. Juneau;A. Meisner;Joseph Wishart;A. Scott;Kyle Matt;R. Ni
我们宣布NOIRLab源目录(NSC)的第二个数据版本(DR2)，使用来自CTIO-4 m+DECam、KPNO-4 m+Mosaic3和BOK-2.3 m+90Prime的412,116个公共图像。NSC DR2包含超过39亿个独特的天体，680亿个单独的源测量，覆盖≈35,000平方度的天空，在大多数宽带滤光片中具有≈23 MAG的深度，光度测量精度为≈1%-2%，天体测量精度为≈7 mA。在≈30,000平方度的天空中，大约有19亿个物体在三个或更多个波段进行光度测量。与NSC DR1相比，它有几个改进。DR2的风险敞口比DR1多156,662(61%)，持续时间比DR1多两年。通过使用Skymapper DR1和ATLAS-Ref2星表，GRIZ的南方光度零点更加准确，并对高消光区使用了改进的消光校正。此外，在校准单个图像的天体测量时，利用Gaia DR2自身运动的优势提高了天体测量的精度。这将NSC本身的运动提高到∼2.5Mar Yr−1(精度)和∼0.2Mar Yr−1(精度)。使用DBSCAN算法和每个对象的平均参数(例如平均幅度、自行等)将源组合成独特的对象。对于异常值拒绝，计算得更稳健。最后，为每个目标计算8个多波段光度可变性指数，并标记可变目标(2300万个目标)。NSC DR2将用于探索太阳系物体、恒星流、矮小卫星星系、准恒星物体、变星、高自行恒星和瞬变。本文提供了这些科学用例的几个例子。NSC DR2星表可通过NOIRLab的Astro Data Lab科学平台公开获取。
We announce the second data release (DR2) of the NOIRLab Source Catalog (NSC), using 412,116 public images from CTIO-4 m+DECam, the KPNO-4 m+Mosaic3, and the Bok-2.3 m+90Prime. NSC DR2 contains over 3.9 billion unique objects, 68 billion individual source measurements, covers ≈35,000 square degrees of the sky, has depths of ≈23 mag in most broadband filters with ≈1%–2% photometric precision, and astrometric accuracy of ≈7 mas. Approximately 1.9 billion objects within ≈30,000 square degrees of sky have photometry in three or more bands. There are several improvements over NSC DR1. DR2 includes 156,662 (61%) more exposures extending over 2 more years than in DR1. The southern photometric zero-points in griz are more accurate by using the Skymapper DR1 and ATLAS-Ref2 catalogs, and improved extinction corrections were used for high-extinction regions. In addition, the astrometric accuracy is improved by taking advantage of Gaia DR2 proper motions when calibrating the astrometry of individual images. This improves the NSC proper motions to ∼2.5 mas yr−1 (precision) and ∼0.2 mas yr−1 (accuracy). The combination of sources into unique objects is performed using a DBSCAN algorithm and mean parameters per object (such as mean magnitudes, proper motion, etc.) are calculated more robustly with outlier rejection. Finally, eight multi-band photometric variability indices are calculated for each object and variable objects are flagged (23 million objects). NSC DR2 will be useful for exploring solar system objects, stellar streams, dwarf satellite galaxies, quasi-stellar objects, variable stars, high proper-motion stars, and transients. Several examples of these science use cases are presented. The NSC DR2 catalog is publicly available via the NOIRLab’s Astro Data Lab science platform.