Hi! Probably a star in a flash. Possible type of variability cataclysmic CV. At the interval 15.8-17.2 UT on 24/12/2017 the brightness is constant 13.2 + -0.05 TG. This interesting red star shines in the UV light and has limits of 13 -> 16V according to ASAS-SN data. I use 200 mm Newton + DSLR Canon 400D. All the best, Ivan Sergey