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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The Clementine Gnomon is a solar meridian telescope dedicated to solarastrometry operating as a giant pinhole dark camera, being the basilica ofSanta Maria degli Angeli the dark room. This instrument built in 1701-1702 bythe will of pope Clement XI by Francesco Bianchini (1662-1729) gives solarimages free from distortions, excepted atmospheric refraction, because thepinhole is opticsless. Similar historical instruments are in Florence (Duomo,by Toscanelli and Ximenes), Bologna (San Petronio, by Cassini), Milan (Duomo,by De Cesaris) and Palermo (Cathedral, by Piazzi). The azimut of the ClementineGnomon has been recently referenced with respect to the celestial North pole,and it is 4'28.8"\pm0.6", a comparison with similar coeval instruments ispresented. Also the local deviations from a perfect line are known with anaccuracy better than 0.5 mm. With these calibration data we used the Gnomon tomeasure the delay of the solar meridian transit with respect to the timecalculated by the ephemerides (DUT1). The growth of this astronomical parameteris compensated by the insertion of a leap second ad the end of the year inorder to keep the Universal Time close to astronomical phenomena within lessthan a whole second. On December 31, 2008 at 23:59:59 there is one of thoseleap seconds leading to 23:59:60 before the new year's midnight 00:00:00, beingDUT1\approx0.7 s at that date. DUT1 has been measured with an accuracy of\pm0.3 s.

Misura del ritardo accumulato dalla rotazione terrestre, DUT1, alla meridiana clementina della Basilica di Santa Maria degli Angeli in Roma