Also makes sense with the RABe 523 unit that they put on Twitter the other day - Luzern looks like the one.
And there's also a poster of Luzern in the 150, so it's almost guaranteed to be a route out of Luzern.
Fyi it's from https://www.openrailwaymap.org/ - I highly recommend it. Has no orthophoto function, but you will not get any other worldwide online map as deatiled when it comes to railways.