Thanks for the warning

A press release from the Wellington City Council today explains some of last night's rattle & hum:

The public of the greater Wellington area are advised that the Royal New Zealand Air Force (RNZAF) will be conducting a military exercise based in the Wellington region on the evenings of the 23, 24 and 27 June 2010. 

Iroquois helicopters from No. 3 Squadron RNZAF will be practising tactical low flying operations at night, utilising night vision equipment, between sunset and midnight.

On 27 June there will be extensive operations in the Central Business District during these hours.

No. 3 Squadron is required to conduct exercises in order to provide capable and timely response options in support of the New Zealand Government's needs.