You can ask for ToO time (http://www.astro.caltech.edu/observatories/coo/solicit/2016A...), but it has to be approved as part of the semi-annual solicitation for observing time. When you use it, you have to notify the PI you bumped and a committee, and later report back to them on the results.
Postdocs don't have to give up their observing for a ToO, but faculty do.
In Caltech's policy, interrupted observers don't get payback time.
http://www.astro.caltech.edu/observatories/coo/TOO/ToOpolicy...
You can ask for ToO time (http://www.astro.caltech.edu/observatories/coo/solicit/2016A...), but it has to be approved as part of the semi-annual solicitation for observing time. When you use it, you have to notify the PI you bumped and a committee, and later report back to them on the results.
Postdocs don't have to give up their observing for a ToO, but faculty do.
In Caltech's policy, interrupted observers don't get payback time.