DESI corrector at UCL ready to be shipped
20 June 2018
The Dark Energy Spectroscopic Instrument's (DESI) wide field optical corrector is due to be shipped to the Mayall telescope at Kitt Peak Observatory in Arizona.
![DESI Corrector DESI Corrector](https://www.ucl.ac.uk/astrophysics/sites/astrophysics/files/styles/large_image/public/news-desicorrectorphoto_0.jpg?itok=MxzkGchS)
The Dark Energy Spectroscopic Instrument's (DESI) wide field optical corrector has been fully assembled and tested at UCL and is due to be shipped to the Mayall telescope at Kitt Peak Observatory in Arizona for commissioning.
This is the culmination of five years of work on DESI by the team at UCL. The corrector contains six lenses, the largest of which is 1.2m is diameter, and the whole assembly stands over 2.1m tall and weighs 2.4 tonnes. The lenses were installed and aligned at UCL to a precision of a few 10s of micrometres.
The DESI instrument will undertake a 5 year survey of 35 million galaxies. The primary scientific goal of the survey is to probe the origin of cosmic acceleration by employing the baryon acoustic oscillation (BAO) technique as a "standard ruler" to accurately measure the expansion history of the Universe.