Hello!
I am trying to enable Trackster on our local galaxy to
visualize the mapping results.
But, so far, it is not working.
Is the twobit.loc file necessary for using Trackster? or is it just optional?

Best regards,
Menorca

Twobit files, configured via twobit.loc, are optional. Here is a page that lists all the steps required to get Galaxy genome visualizations (including Trackster) working: http://wiki.galaxyproject.org/Visualization%20Setup

Let us know if you run into any problems or have questions.

Thanks,
J.