The Kepler mission has provided a wealth of data, revealing new insights in time-domain astronomy. However, Kepler's single band-pass has limited studies to a single wavelength. In this work we build a data-driven, pixel-level model for the Pixel Response Function (PRF) of Kepler targets, modeling the image data from the spacecraft. Our model is sufficiently flexible to capture known detector effects, such as non-linearity, intra-pixel sensitivity variations, and focus change. In theory, the shape of the Kepler PRF should also be weakly wavelength dependent, due to optical chromatic aberration and wavelength dependent detector response functions. We are able to identify these predicted shape changes to the PRF using the residuals between Kepler data and our model. In this work, we show that these PRF changes correspond to wavelength variability in Kepler targets using a small sample of eclipsing binaries. Using our model, we demonstrate that pixel-level light curves of eclipsing binaries show variable eclipse depths, ellipsoidal modulation and limb darkening. These changes at the pixel level are consistent with multi-wavelength photometry. Our work suggests each pixel in the Kepler data of a single target has a different effective wavelength, ranging from $\approx$ 550-750 $nm$. In this proof of concept, we demonstrate our model, and discuss possible use cases for the wavelength dependent Pixel Response Function of Kepler. These use cases include characterizing variable systems, and vetting exoplanet discoveries at the pixel level. The chromatic PRF of Kepler is due to weak wavelength dependence in the optical systems and detector of the telescope, and similar chromatic PRFs are expected in other similar telescopes, notably the NASA TESS telescope.
DELOS: Contrastive Deep Learning for Low-SNR Blind Transit Searches in Kepler Photometry
Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China（上海天文台，中国科学院，上海200030，中国）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, Beijing 101408, China（中国科学院大学天文与空间科学学院，北京101408，中国）；Science Talent Training Center, Gainesville, FL, 32606 USA（科学人才培训中心，佛罗里达州盖恩斯维尔，32606 USA）
Kepler Pixel Project -- background RR Lyrae stars in the primary Kepler mission field of view
在本文中，我们描述了一个项目，我们开始调查个人像素在下载的开普勒孔径，以找到对象的主要目标的背景中具有可变亮度。在本系列的第一篇论文中，我们发现并研究了547个短周期食双星（Bienias et al. 2021）。在这里，我们提出了26个新的RR天琴座恒星的开普勒背景像素在主要任务期间获得的独立发现，并提供这些对象的连续和精确的测光。这些恒星中有21颗已经被盖亚或泛星巡天发现。这个新的主要是微弱和遥远的RR天琴座恒星的人口增加了50%，很好地补充了52个已知的主要目标RR天琴座恒星在原来的开普勒领域。尽管它们很微弱，但这些恒星的四年准不间断光变曲线让我们可以前所未有地看到这些微弱的光环物体。我们提出了一个新的RR天琴座样本的光变曲线的分析，验证他们的分类使用傅立叶参数，并讨论这些新发现的脉动变星的属性。最值得注意的是，这是第一次在光度数据集的帮助下，以出色的节奏和精度对这种微弱的RR型天琴座恒星进行了研究。有趣的是，这些对象共享其较亮的兄弟姐妹在子类特征，附加模式内容和调制发生率方面的属性。
