First light (astronomy)

This article is about the testing of telescopes. For the first light of dawn, see Twilight § Nautical twilight. For the cosmogonical age, see first light (cosmology).

First light image from the Kepler space telescope with two points of interest outlined. Celestial north is toward the lower left corner. ^[1]

In astronomy, first light is the first use of a new instrument, typically a telescope to take an astronomical image after it has been constructed. This is often not the first viewing using the telescope because optical tests have likely been performed to adjust the components.

Characteristics

First released image from the Vera C. Rubin Observatory, the Trifid and Lagoon nebulae , released on 23 June 2025.

The first light image is normally of little scientific interest and is of poor quality, since the various telescope elements are yet to be adjusted for optimum efficiency. Despite this, a first light is always a moment of great excitement, both for the people who design and build the telescope and for the astronomical community, who may have anticipated the moment for many years while the telescope was under construction. A well-known and spectacular astronomical object is usually chosen as a subject.^{[ citation needed ]}

See also

• First light (cosmology)

References

1. Atkinson, Nancy (16 April 2009). "Kepler's "First Light" Images". Universe Today . Retrieved 2012-10-13.
2. Chang, Kenneth; Miller, Katrina (23 June 2025). "Vera Rubin Scientists Reveal Telescope's First Images". The New York Times. ISSN   0362-4331 . Retrieved 23 June 2025.
3. Wells, Ione; Rannard, Georgina (23 June 2025). "First celestial image unveiled from revolutionary telescope". BBC . Archived from the original on 23 June 2025. Retrieved 24 June 2025.