I work in Russia these days,here I don’t under stand about sunrise and sunset. We don’t have any local Muslim here. So what we do for fasting just our guess for sehri and aftar.

You should enquire the time of dawn as that is when sehri time ends and
break your fast after sunset time. You may obtain the times for dawn and
sunset from the local newspaper, radio, or internet.

And Allah Ta'ala knows best

Mufti E. Desai