This paper reports results from the first long-term BV (RI) _c photometric CCD observations of three variable pre-main-sequence stars collected during the period from February 2007 to January 2020. The investigated stars are located in the field of the PMS star V733 Cep within the Cepheus OB3 association. All stars from our study show rapid photometric variability in all-optical passbands. In this paper, we describe and discuss the photometric behavior of these stars and the possible reasons for their variability. In the light variation of two of the stars, we found periodicity.

中文翻译：

---

V733 Cephei领域三颗PMS变星的BV（RI）c光度研究

本文报告了 2007 年 2 月至 2020 年 1 月期间收集的三颗可变前主序星的首次长期BV ( RI ) _c光度 CCD 观测结果。被调查的恒星位于 PMS 星的场域Cepheus OB3 协会内的 V733 Cep。我们研究中的所有恒星都显示出全光学通带中的快速光度变化。在本文中，我们描述和讨论了这些恒星的光度行为及其变化的可能原因。在两颗恒星的光线变化中，我们发现了周期性。