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 modified the optical system of 500 mm wide-field telescope of which point spread function showed an irregularity.\udThe telescope has been operated for Near Earth Space Survey (NESS) located at Siding Spring Observatory (SSO) in\udAustralia, and the optical system was brought back to Korea in January 2008. After performing a numerical simulation\udwith the tested value of surface figure error of the primary mirror using optical design program, we found that the surface\udfigure error of the mirror should be fabricated less than root mean square (RMS) λ/10 in order to obtain a stellar full\udwidth at half maximum (FWHM) below 28 μm. However, we started to figure the mirror for the target value of RMS λ/20,\udbecause system surface figure error would be increased by the error induced by the optical axis adjustment, mirror cell\udinstallation, and others. The radius of curvature of the primary mirror was 1,946 mm after the correction. Its measured\udsurface figure error was less than RMS λ/20 on the table of polishing machine, and RMS λ/15 after installation in the\udprimary mirror cell. A test observation performed at Daeduk Observatory at Korea Astronomy and Space Science Institute\udby utilizing the exiting mount, and resulted in 39.8 μm of stellar FWHM. It was larger than the value from numerical\udsimulation, and showed wing-shaped stellar image. It turned out that the measured-curvature of the secondary mirror,\ud1,820 mm, was not the same as the designed one, 1,795.977 mm. We fabricated the secondary mirror to the designed\udvalue, and finally obtained a stellar FWHM of 27 μm after re-installation of the optical system into SSO NESS Observatory\udin Australia

Performance Improvement of Near Earth Space Survey (NESS) Wide-Field Telescope (NESS-2) Optics