Last day this year will be a regular BC547 transistor. I hope you have liked this little advent calendar, its been fun to figure out all of the devices to measure.
As you can see, the beta of the device corresponds well to 250.
All of the pictures are taken on a Tektronix 576 Curve tracer, using a photo hood from [1] and a iPhone.
[1] https://www.thingiverse.com/thing:2096029
RF and electronics blog LA3PNA 
Lovely curve tracer photos, have you tried a TL431?
They used to produce quite an interesting trace, I hope they still do.