Ruprecht 147 won't run through K2-SS, cannot _get_source_mask

[christinahedges]

Not sure why this one is breaking, might need @jorgemarpa to take a look!

Check out a gist here: https://gist.github.com/christinahedges/5f97f447399f0d0861e3aefae99b2530

[jorgemarpa]

Noted, I'll get the data and check what's going on here.