Abstract Exoplanet research is now target rich with a wide diversity of systems making it difficult for high demand observatories to undertake follow up observations over extended periods of time. We investigate the effectiveness of using 0.4m-class telescopes for monitoring transiting hot Jupiters and their host stars. We consider two representative case studies: WASP-52b with 13 new transits, and HAT-P-23b with 17 new transits and concurrent photometric monitoring covering 78 days. We present updated system parameters and combine our new transit times with previously published results to calculate new ephemerides for both systems. Our analysis of transit mid-times for WASP52b results in a slight preference for a quadratic ephemeris (∆χ2ν = 0.07, ∆BIC = 1.53 over a linear ephemeris. We discuss the reality of this quadratic ephemeris indicating a period change of δP/δt = −38.6 ± 4 ms yr−1 and consider possible causes. WASP-52 is known to be an active star with previous publications reporting many spot crossing events, however no such events are seen in our new photometry. Our analysis shows that WASP-52 is still active and that the latitude of the spots has likely migrated away from the transit chord. We confirm the inflated nature and circular orbit for HAT-P-23b. Our monitoring of HAT-P-23 reveals a periodicity of 7.015 days with an amplitude of 0.011 mag which we interpret as the rotation period of HAT-P-23. The photometric and transit timing precision achieved in the case studies shows that this class of telescope is capable of precise characterisation and long-term monitoring of transiting hot Jupiters in support of dedicated ongoing and future ground and space based observations.

中文翻译：

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用小口径望远镜监测凌日系外行星及其主星

摘要 系外行星研究现在的目标很广泛，系统种类繁多，这使得高需求的天文台很难进行长时间的后续观测。我们调查了使用 0.4m 级望远镜监测凌日热木星及其主星的有效性。我们考虑两个有代表性的案例研究：WASP-52b 有 13 个新过境，HAT-P-23b 有 17 个新过境和覆盖 78 天的并发光度监测。我们提供更新的系统参数，并将我们的新传输时间与之前发布的结果相结合，以计算两个系统的新星历。我们对 WASP52b 中转时间的分析导致对二次星历略有偏爱（∆χ2ν = 0.07，∆BIC = 1.53 超过线性星历。我们讨论了这个二次星历表的现实，表明 δP/δt = -38.6 ± 4 ms yr-1 的周期变化，并考虑可能的原因。众所周知，WASP-52 是一颗活跃的恒星，之前的出版物报告了许多点交叉事件，但是在我们的新光度测量中没有看到此类事件。我们的分析表明 WASP-52 仍然活跃，并且这些斑点的纬度可能已经从过境弦移开。我们确认了 HAT-P-23b 的膨胀性质和圆形轨道。我们对 HAT-P-23 的监测揭示了 7.015 天的周期，振幅为 0.011 mag，我们将其解释为 HAT-P-23 的自转周期。