We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE; Wright et al. 2010) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS; York et al. 2000). We use a "forced photometry" technique, using measured SDSS source positions, star-galaxy separation and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our "unWISE" coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero. However, for many sources we get three- or four-sigma measurements; these sources would not be reported by the WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.
Photometric Cross-Calibration of the SDSS Stripe 82 Standard Stars catalogue with Gaia EDR3, and Comparison with Pan-STARRS1, DES, CFIS and GALEX catalogues
我们用2007年后的SDSS成像数据扩展了SDSS Stripe 82标准星表。这个改进的版本列出了近100万颗比r~22等亮的恒星的平均SDSS ugriz测光。每颗恒星的测量值增加了2- 3倍，随机误差比原始星表小1.4- 1.7倍，比单个SDSS运行小约3倍。在新星表中，u、g、r、i和z波段亮度分别超过20.0、21.0、21.0、20.5和19.0等的恒星的随机误差< 0.01等。我们通过使用盖亚早期数据发布3（EDR 3）Gmag测光来获得灰度测光零点校正，作为R.A.和December，用于SDSS目录，并使用Gaia BP-RP颜色来导出ugiz波段相对于r波段的校正。经Pan-STARRS 1、DES、CFIS和GALEX巡天测试的重新校准的测光质量表明，测光零点的空间变化<=0.01 mag（RMS），在R.A.的典型值为3-7毫等，而在十倍方向上为1-2毫等，除了在u波段中<6毫等的散射。我们还报告了一些小的测光问题与其他调查考虑在这里，包括一个依赖于星等的~0.01 mag之间的偏差16 < G_盖亚< 20在盖亚EDR 3。我们新的公开目录提供了低于1%水平的ugriz测光的强大校准，并将在Vera C的调试期间提供帮助。Rubin Observatory Legacy Survey of Space and Time的照片
Empirical colour--effective temperature relations in the SDSS system from IRFM temperatures of GALAH and APOGEE stars
Yunnan Astronomical Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天体物理与天文研究学院）；International Centre of Supernovae (ICESUN)（超新星国际中心）；University of the Chinese Academy of Sciences（中国科学院大学）；CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台光学天文重点实验室）
