There is, of course, no way for a rainbow to ever be visible when the light source is always directly overhead (not to mention being rod-shaped rather than a point source), hence Sam’s confusion (Juni combined the Hiero words meaning ‘rain’ and ‘arch’ with a containment-conjunctive).
Meanwhile, the deep-space background is blue with tinges of infrared (I took some artistic license), so blue- and red-shift look a bit counterintuitive, with the background appearing purple and cyan, respectively. This is actually correct for a relative velocity of 0.027c. Deriving this, as well as determining how long they’ve been accelerating in order to be at this speed having traveled only about ¼ of the way to the galactic core from Earth, is left as an exercise for the reader; show your work, and don’t forget to account for the Lorentz effect, the increase in mass due described by special relativity, and increase in drag due to the interstellar hydrogen pressure front while accounting for the ramscoop feed, as well as whatever theories of dark matter, spatio-temporal expansion, and quantum velocity you subscribe to.
Incidentally, I may have too much time on my hands.