You are stationary at a great distance from a black hole, wearing a suit which is shining at a particular frequency f0. Your friend sets off on a trip towards the black hole, with a speed which is close (but slightly lower) than the speed of light. In class I described how you will see your friend moving. In particular, you will never see your friend enter the black hole, while your friend will enter at a finite time according to their clock. 

Describe how your friend will see your suit shining. 

Justify your answer either with an equation or with a space-time diagram.