These observations can take place in the media or through personal experience.

I'd like to know where and when the observation took place.

The observations of the two individuals took place in January 1874.

Expanded observations of the flight will also take place on the ground.

The last known observation of the comet took place on November 2.

"So my observations will take a few minutes to spell out."

Each observation took between 10 minutes to a little over an hour.

All this observation had not taken very long, but it was enough.

His magnetic observations mostly took place from 1823 to 1826.

The observations are easy to make and should take only about 15 minutes.