We conducted a global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey - a prototype of the SPECULOOS transit search conducted with the TRAPPIST-South robotic telescope in Chile from 2011 to 2017 - to estimate the occurrence rate of close-in planets such as TRAPPIST-1b orbiting ultra-cool dwarfs. For this purpose, the photometric data of 40 nearby ultra-cool dwarfs were reanalysed in a self-consistent and fully automated manner starting from the raw images. The pipeline developed specifically for this task generates differential light curves, removes non-planetary photometric features and stellar variability, and searches for transits. It identifies the transits of TRAPPIST-1b and TRAPPIST-1c without any human intervention. To test the pipeline and the potential output of similar surveys, we injected planetary transits into the light curves on a star-by-star basis and tested whether the pipeline is able to detect them. The achieved photometric precision enables us to identify Earth-sized planets orbiting ultra-cool dwarfs as validated by the injection tests. Our planet-injection simulation further suggests a lower limit of 10 per cent on the occurrence rate of planets similar to TRAPPIST-1b with a radius between 1 and 1.3 $R_\oplus$ and the orbital period between 1.4 and 1.8 days.

中文翻译：

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TRAPPIST 超冷矮星运输调查的全球分析

我们对 TRAPPIST 超冷矮矮星凌日调查（2011 年至 2017 年在智利使用 TRAPPIST-South 机器人望远镜进行的 SPECULOOS 凌日搜索的原型）进行了全球分析，以估计诸如 TRAPPIST 等近距离行星的出现率-1b 轨道超冷矮星。为此，从原始图像开始，以自洽和全自动的方式重新分析了附近 40 个超冷矮星的光度数据。专门为此任务开发的管道可生成差分光变曲线，去除非行星光度特征和恒星变异性，并搜索凌日。它无需任何人为干预即可识别 TRAPPIST-1b 和 TRAPPIST-1c 的过境。为了测试管道和类似调查的潜在输出，我们逐星地将行星凌日注入光变曲线，并测试管道是否能够检测到它们。达到的光度精度使我们能够识别出地球大小的行星围绕超冷矮星运行，正如注入测试所验证的那样。我们的行星注入模拟进一步表明，类似于 TRAPPIST-1b 的行星出现率的下限为 10%，半径在 1 到 1.3 $R_\oplus$ 之间，轨道周期在 1.4 到 1.8 天之间。