I believe that the last official announcement from the Imperial Palace was on 21. Jan. 3301, confirming the delay of the Emperor's marriage, with Chancellor Blaine stating that the Emperor is too unwell to participate in his wedding ceremony. (See the
GalNet archive.) Since then, the wedding has been postponed indefinitely, and as GalNet mentioned, this hasn't come as a surprise to those in power.
So, the Emperor is dying, but it's not the senators who would announce his death, but the Imperial Palace, most probably Chancellor Blaine. I would imagine everyone is secretly getting ready for a succession war, in case the Emperor dies before his wedding, leaving no clear line of succession.