With Venus out of the picture for a few months, I've discovered a new twilight astronomy challenge - Sirius-spotting. I caught it yesterday with the Sun's altitude at -4 degrees (ie 4 degrees below the horizon), and tonight I've just managed to catch it with the Sun at -3.4 degrees.
I suspect there's an O(n**-x) in the relationship between the Sun's negative altitude and the chance of seeing Sirius, because I couldn't see it at all at -2 degrees, despite much scanning.
