Not sure what it is exactly, species wise, but if it's in that tub, maybe put a half toilet roll tube or two, along with some paper for flooring. An empty jar lid with some water in too would be good. After that, put a lid on it, if you are willing to sacrifice a tub, put some holes in the top of the lid for air, if not, leave it slightly ajar, looks like a steep tub so it shouldn't escape.
Leave it in a dark warm area of the house for now until someone gives you some better information, these current temps we're having will suffice for now.
So, to simplify:
Lid with holes
Kitchen paper, newspaper as flooring
Half toilet roll tubes x2, maybe 3
Cleaned out jar lid/milk bottle lid with water in it
Leave in dark warm area of house