I see 1:60, but not the 1:43. Can you post the URL? Thanks.
Near-Earth Asteroid 2004 MN4 Reaches Highest Score To Date On Hazard Scale
http://neo.jpl.nasa.gov/news/news146.html
The URL of the official JPL/NASA tracking data page for this asteroid is:
http://neo.jpl.nasa.gov/risk/2004mn4.html
Even if the final analysis does not move much, some of the supporting data is updated as observatories report in and it is added to the model. This page seems to be changing daily.
Right now, almost all the data is coming in from observatories south of the equator, as the asteroid is somewhere in the vicinity of the South Pole currently, making the participants a bit sparse. It will become visible in to observatories north of the equator in a little bit, which is also where a lot of the observatories that can track this thing actually are.
At the top of the table on http://neo.jpl.nasa.gov/risk/2004mn4.html, the most recent numbers are 2.2e-2, or about 1 in 43.