Why the Chelyabinsk Bolide is Unrelated to Asteroid 2012 DA14
Tonight at 19:25 UTC the 50 meter asteroid 2012 DA14 will scrape past the Earth at less than 28,000 km distance. This morning, a smaller object entered the atmosphere over Chelyabinsk, Russia, where it exploded at an altitude of some tens of km. The shock wave of its sonic boom and explosion caused damage and injuries, and it is likely that some debris also reached the surface. The fact that both events occur on the same day has led to speculation that they must be related, i.e., that the Chelyabinsk object might have been associated with 2012 DA14 in some way. There are different ways to disprove this notion. I choose the simplest way.
The first thing to do is to check 2012 DA14's approach direction. I get its trajectory data from the JPL Horizons web interface. Then I straightforwardly compute the latitudes and local times at which atmospheric entry (assuming it takes place at 100 km altitude) occurs for an object that travels in the same direction as 2012 DA14 but is displaced in any direction by some thousands of km. The result is plotted below, for different entry flight path angles:
The object that entered above Chelyabinsk did so at around 9:30 local time. Now, let's see. I read off in the diagram that atmospheric entry at that time, even at a shallow entry angle of -15 degrees, would take place at around 5 degrees northern latitude, travelling almost exactly due North. For steeper entry angles, it would have entered even further south.
However, Chelyabinsk is at situated at 55 degrees North. No way a 2012 DA14-related object could have appeared there, even allowing for even shallower entry and considerable atmospheric travel between entry and break-up. Independently of other plausible arguments that also disprove any relationship between the Chelyabinsk bolide and 2012 DA14, this already constitutes sufficient evidence.
The Chelyabinsk object is unrelated to 2012 DA14. End of the matter.