I'm trying to understand some of the stellar ages that the Tipsy example data (the isolated galaxy) at:

When I examine the formation time with the super-simple script:

http://paste.yt-project.org/show/5501/

I get: 

max star age:  100.000499852 Gyr

I thought normally the formation time was the current simulation time minus the stellar age for Tipsy outputs - am I interpreting this wrongly?

Thanks,
desika