Paulus Magintie:
Ok i'll reprase that its the fast slipspace ship
That is still something we dont know. All the UNSC Gettysburg has is an adapted Covenant Slipspace Drive attached to it. No special power source. And considering that the Gettysburg was running at only 67% capasity due to damage. We dont know if the Engineers repaired that damage, or made further modifications to the Gettysburg's reactor.
For that matter speed and time are completely relative in Slipspace. As far as I am aware Covenant vessels dont travel "faster" in Slipspace than UNSC vessels, they travel more accurately. That allows them to shave of some time from their jump. And dont point to me and say that they travel at 912 lightyears a day because there is a major problem with that.
Onyx is approximately 38 lightyears away from Earth. The UNSC Dusk followed a Covenant crusier (Regrets cruiser) to Installation 05 for 13 days being pulled along at roughly the same "speed". So lets see here thats 13 * 912 = 11,856 lightyears.
That would mean that Installation 05 is nearly 12,000 lightyears away from Earth. And yet some how the UNSC Dusk manages to get back to Earth in less than 6 hours and give a full report to Lord Hood about the situation at Installation 05 and then Slipspace jump to Onyx (still with in the 6 hour timeframe) and arrive at 2040 hours that day.
Here let me give you a timeline so its not so confusing.
1440 hours, November 3, 2552: The UNSC Dusk arrives at Installation 05 to witness the start of the Covenant Civil War.
2040 hours, November 3, 2552: The UNSC Dusk arrives at Onyx before the main fleet from Earth shows up (total of 8 vessels including the UNSC Dusk)
Some where between those two times the UNSC Dusk managed to stop at Earth, brief Lord Hood about the Covenant Civil War and then left for Onyx.
UNSC vessels dont travel faster than 2.1 lightyears per day correct? That means in order to travel the nearly 12,000 lightyears from Installation 05 to Earth they would have been gone for ~5,646 days. Thats about 15 and a half years.... Then the travel time from Earth to Onyx is ~18 days.
In both directions they didnt have a wake to follow. But for arguments sake I will include one...
From the jump to Earth from Installation 05 they could have possably, and I am really stretching that, caught some of the wake left by the Forerunner Dreadnought when it left Installation 05. Even so that vessel did not travel directly to Earth if you believe that some of the comics are canon (Halo: Uprising spesificly). They display that the Dreadnought was caught up in some trouble for that journy and it took it a significant amount of time to reach Earth. So the wake they would have caught would have been very very weak and would have disipated shortly after they caught it. Not only that but it wasnt even traveling in the same direction as Earth...
Going from Earth to Onyx there wasnt a bloody Covenant vessel to follow.... so there was no wake to catch on to.
See the problem here?