Not really, there are millions of amateur astronomers, and any asteroid capable of catastrophic Earth damage could be seen months before it hits, the smaller ones, like the one in Russia, will always be missed mostly, too small to see.If government high officials see a world- threatening asteroid coming they will prepare themselves but keep it quiet. Otherwise they will get swamped.
I've seen a meteorite hit Earth, it wasn't on the news BUT I was in a remote part of the world and it was at 3 in the morning, so may have been the only witness !!!
These things are hitting somewhere on Earth pretty regularly but since most of the Earth isn't populated we never get to hear about them.
To cover up a major asteroid strike the governments would have to kill millions of amateur astronomers, and even then an Extinction Level Event asteroid could be seen with the naked eye weeks before impact.
TBH there is no point in covering things up, we can't do anything about it, there is nowhere to hide or run, for sure the top-dogs will have a plan, the mega-rich and the top government officials perhaps, but the real problem is the aftermath, there would be no food production for years, possibly, people living in underground bunkers can only stay down for so long, could be, ultimately, that the top-dogs know it is hopeless, al you are doing is delaying your inevitable death.
I think that the government WOULD tell the truth about an impact BUT possibly lie about the outcome. If they said it was going to hit but most of us will be OK, folks would probably carry on with life until the giant bang kills them all!!!
Most amusing of all is that the survivalist redneck racists will be in a better position to survive than nearly anyone else in the US, they have food and water for up to a year, and underground bunkers. If an asteroid didn't hit them directly they stand a good chance of survival, for a year or so at least, after that, where they going to get food?
Funny to think that in the event of such a cataclysmic event to America, that the US population may be just a few hundred rednecks lol
For sure, anyone living in a city is history, cities need daily supplies of food and such, look at how even just a day of snow can cause shortages. I believe that governments worldwide know that cities will just be laid waste, humans have faced extinction before, and the reason we didn't was because small groups of people lived in different places, groups small enough for the land to feed and yet big enough to be a viable population.
Personally, I would be more concerned with Yellowstone erupting or the magnetic pole reversal, the magnetic field is 6% weaker today than 100 years ago, many scientists think that is the sign of it reversing, during reversal we have NO protection from solar and cosmic rays, except that atmosphere. Melanin will not protect anyone, the levels of solar radiation will destroy our DNA.