First light (astronomy)

The first moment of the light is referred to in astronomy in which the light of a star falls to the first mirror or lens of a new telescope. This is true not only for the telescope itself, but also for the connected instruments, which one ascribes their own as First Light.

During start-up of lasers, the expression for the first generated light is used before the laser is operated with its maximum power.

The term is often used in the German language in the English version first light.

Astronomy

Usually First light images do not have high scientific importance and are of lower quality than later recordings, as the telescope or instrument is not yet fully adjusted. Often, well-known or spectacular astronomical objects are selected with a high recognition value for the first image.

For the designers and builders of a new telescope is the moment of "first light " an exciting and important event, but also for larger parts of the astronomical experts. In particular, the first light of a new telescope type - as seen recently that of the Large Binocular Telescope - is usually world-wide interest.

• Optical telescope