Today Zhytomyr is in Ukraine. I think "Celleitz" may refer to one of two villages in that area: one is a suburb of Zhytomyr, now called Sloboda-Selets', and the other is a bit farther north called Selets', near the town of Zhad'ky. In the 19th century they were both simply called "Selets."

Hope this helps.

Jonathan Sherman
Toronto, Canada