var newTime = theTime.UtcNow.ToString("o");
// returns "2017-06-26T00:00:00.0000000Z"
var newTime2 = theTime.Date.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss.sssZ");
// returns "2017-06-26T00:00:00.00Z"
var newTime = theTime.Date.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss.fffZ");
// returns "2017-06-26T00:00:00.000Z"