Why isn't Moses Ziwjan's Yahrzeit Exact?

We do not know the exact date of death of Moses Ziwjan. According to Jewish tradition, if the exact date of death is not known, the yahrzeit of a person can be observed on any day, as long as it is that same day every year. Since that is the case, we observe the yahrzeit of Moses Ziwjan on 19 Tevet. If you know the exact date of death of Moses Ziwjan, contact us via the contact page. Be sure to include the url: https://eachofushasaname.org/person/6248/Moses_Ziwjan.html