English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We have developed and tested a novel method, based on LIDAR, of measuring theheight and profile of the mesospheric sodium layer using a continuous wavelaser. It is more efficient than classical LIDAR as the laser is on for 50% ofthe time, and so can in principle be used during laser guide star adaptiveoptics observations. It also has significant advantages over direct imagingtechniques because it does not require a second telescope, is almostindependent of the atmospheric conditions, and avoids triangulation problems indetermining the height. In the long term, regular monitoring using this methodwould allow a valuable database of sodium layer profiles, heights, and returnflux measurements to be built up which would enable observatory staffastronomers to schedule observations optimally. In this paper we describe theoriginal experiment carried out using the ALFA laser guide star system at CalarAlto Observatory in Spain. We validate the method by comparing the LIDARresults with those obtained from simultaneous imaging from an auxiliarytelescope. Models are presented of a similar system to be implemented in theVery Large Telescope Laser Guide Star Facility, which will enable the initialfocus setting for the adaptive optics systems to be determined with an accuracyof less than 200 m on a timescale of 1 minute.Comment: Accepted for publication in Astronomy & Astrophysics, 12 pages, 14  figure

Measuring the absolute height and profile of the mesospheric sodium layer using a continuous wave laser