1,000 feet is not a "planet killer". Would be roughly 2-3 times the size of the Tsar Bomba explosion. If you were 200 miles from impact, you'd experience a 6.7 magnitude earthquake, some slight overpressure, but no ejecta or thermal effects. Dust would certainly cool the earth for a couple years, but there wouldn't be a "nuclear winter".
It would suck bad if it landed within 50 miles of your location though.