It was first observed in the 1970s but not actually described to science until 2005.

The effects of this conflict continued to be observed until the year 1703.

He visited Earth six times and observed it from just after its creation until 1922.

It's almost as if they sat back observing us until the last minute.

Only in some areas a continuity of these cultures is observed until the 5th and 6th centuries.

The important thing was not to let them know they were observed until the crucial, incriminating moment had arrived.

For example, Mercury was not observed in the infrared spectrum until 1995.

The nebula was not observed after 2004 until 2008, when it reappeared once more.

Belmont remained on station observing conditions until the middle of July.

Finally, on Saturdays, a vigil is observed from midnight until early morning.