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arXiv 2305.16630astro-ph.IM
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DESI成像与Gaia合成测光的光度定标比较

Comparing the Photometric Calibration of DESI Imaging and Gaia Synthetic Photometry

Rongpu Zhou, Arjun Dey, Dustin Lang, John Moustakas, Edward F. Schlafly, David J. Schlegel

AI总结:

本文通过将DESI遗留巡天恒星测光与Gaia DR3合成测光对比,量化了LS的定标系统误差及其空间模式,并确认DR10修正了DR9在南天区的大尺度测光偏移。

摘要:

DESI遗留巡天(LS)的相对光度定标误差被用于DESI目标选择,可能在DESI目标密度上留下印记,并使最终的宇宙学测量产生偏差。我们通过将LS恒星测光与Gaia DR3合成测光进行比较来刻画LS定标系统误差。我们发现,当在27角分的角尺度上取平均时,LS DR9与Gaia的恒星测光在DECam的grz三个波段分别存在4.7、3.7、4.4 mmag的均方根(rms)差异。测光偏移中存在明显的空间模式,类似于Gaia扫描模式(在合成的g波段最为显著),这表明Gaia分光光度定标中存在系统误差;同时也存在由LS定标系统误差引起的蜂窝状模式。我们还发现LS DR9中在赤纬小于-29.25度的区域存在大尺度且平滑变化的测光偏移,这些问题在DR10中已得到修正。

英文摘要:

The relative photometric calibration errors in the DESI Legacy Imaging Surveys (LS), which are used for DESI target selection, can leave imprints on the DESI target densities and bias the resulting cosmological measurements. We characterize the LS calibration systematics by comparing the LS stellar photometry with Gaia DR3 synthetic photometry. We find the stellar photometry of LS DR9 and Gaia has an \textsc{rms} difference of 4.7, 3.7, 4.4 mmag in DECam $grz$ bands, respectively, when averaged over an angular scale of 27 arcmin. There are distinct spatial patterns in the photometric offset resembling the Gaia scan patterns (most notably in the synthesized $g$-band) which indicate systematics in the Gaia spectrophotometry, as well as honeycomb patterns due to LS calibration systematics. We also find large and smoothly varying photometric offsets at $\mathrm{Dec}<-29.25^{\circ}$ in LS DR9 which are fixed in DR10.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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