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/

Zendy Pro

Presents the zaia usage as premium feature

ZAIA

Presents AI Discovery search usage as a premium feature

AI Discovery

Presents AI Discovery explain and summary usage as a premium feature

Content Analysis

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Presents the pdf analysis as premium feature

PDF Analysis

1500 Top-up

3000 Top-up

Zendy Basic

2500 Top-up

Zendy Unlimited

Presents the access of premium content as premium feature

Premium Content

The solar diameter has been monitored at the Royal Observatory of the SpanishNavy (today the Real Instituto y Observatorio de la Armada: ROA) almostcontinuously since its creation in 1753 (i.e. during the last quarter of amillennium). After a painstaking effort to collect data in the historicalarchive of this institution, we present here the data of the solar semidiameterfrom 1773 to 2006, making up an extensive new database for solar-radiusmeasurements can be considered. We have calculated the solar semidiameter fromthe transit times registered by the observers (except values of the solarradius from the modern Danjon astrolabe, which were published by ROA). Thesedata were analysed to reveal any significant long-term trends, but no suchtrends were found. Therefore, the data sample confirms the constancy of thesolar diameter during the last quarter of a millennium (approximately) withininstrumental and methodological limits. Moreover, no relationship between solarradius and the new sunspot-number index has been found from measurements of theROA. Finally, the mean value for solar semidiameter (with one standarddeviation) calculated from the observations made in the ROA (1773-2006), afterapplying corrections by refraction and diffraction, is equal to 958.87" \pm1.77"

Monitoring the Solar Radius from the Royal Observatory of the Spanish Navy during the Last Quarter-Millennium