It is for the new operation from TXL where they employ a dozen or so leased aircraft from WDL, Condor and SmartLynx for the next couple of weeks, ranging from 146s to 757-300.
The 146s are used on the routes from TXL to ZRH (a -300) and VIE (a -200) as these do not require more capacity a this point - remember, the whole TXL operation has started with a very short lead-in time and the loads at the moment are often very light.