Roscosmos, the Russian Federal Space Agency, says the ISS was reboosted 3.7 km.
The readjustment, which took place March 18, was necessary to ensure the best conditions to dock Russia's Soyuz TMA-21 piloted spacecraft and the U.S. Endeavor space shuttle. Russia's Soyuz TMA-21 is expected to travel to the ISS sometime in early April, while the U.S. Endeavor will blast off from Cape Canaveral on April 19.
According to the Roscosmos press release the maneuver was conducted using the two main engines on board the European Space Agency's Automated Transfer Vehicle (ATV-2), named after Johannes Kepler.
Since the orbital period changes roughly 1.2 seconds for each 1 km of altitude, observers on the ground should see almost 5 seconds of change. The usual caveats about tracking program ISS discrepancies should be kept in mind until the Keplerian Elements catch up.
- TNX to Southgate ARC