Theres a problem for intergalactic astronauts which is finding their way back to Earth. Combining all the rotational speeds, we are spinning and orbiting the sun, in our solar system which is spinning in the Milky Way, which is spinning in a large cluster, which in turn spins in a super cluster. Combining all the speed of the rotational forces equals 1.5 million mph. Said Intergalactic Astronaut would have a job to find where the Earth is if they flew into space and out of the super cluster. But my question is this, the astronaut HAS managed to find a ship to leave the Earth, the solar system, the Milky Way, the Large cluster, the Super cluster and is at relative to us, is motionless in space, observing us. How much faster is time for the astronaut? Or how much slower is time for us on Earth, given the speed of Earth and gravitational effect on time.
I think what you mean is that the astronaut is in the same frame-of-reference as the centre of the 'super cluster'. If the astronaut was motionless relative to us then she/he would experience/measure the same flow of time as us. You should note that the commonality between Galilean and `Einsteinian' relativity is that there is there is no single absolute 'frame' in which speed can be measured relative to - even empty space!
If the astronaut was at the centre of the super cluster structure that you're referring to then you might expect the relative time dilation factor to be ~1.0000025.