Wolfgang, You put improper questions. The only correct sundial is a sundial that indicates the local time.
Willy Leenders Hasselt in Flanders (Belgium) Visit my website about the sundials in the province of Limburg (Flanders) with a section 'worth knowing about sundials' (mostly in Dutch): http://www.wijzerweb.be Op 23-nov-2015, om 19:01 heeft Wolfgang R. Dick het volgende geschreven: > ITU-R has decided not to decide anything now on the future of > leap seconds, but has postponed a decision to 2023 - see below. > > By the way, am I right that all sundials would show wrong time > earlier or later if no leap seconds would have introduced? > (I mean at least the precise sundials which correct for the > equation of time and show time with a precision of minutes or even > better.) > > A second question: What are the most precise sundials? In Furtwangen > I saw a large sundial with a claim to disply time to a second, > but I could not recognize this precision on the sundial itself. > > And a third question: Are there already thoughts how to construct > a precise sundial in a world without leap seconds, when the zero > meridian for time will no longer be coincide with the geographic > zero meridian and will be shifted eastwards with time? > > Best regards, > Wolfgang > > > Coordinated Universal Time (UTC) to retain "leap second" > > New reference time scale to be considered by World Radiocommunication > Conference in 2023 > > Geneva, 19 November 2015 - The ITU World Radiocommunication Conference > (WRC-15), currently in session in Geneva from 2 to 27 November, has > decided that further studies are required on the impact and application > of a future reference time-scale, including the modification of > coordinated universal time (UTC) and suppressing the so-called "leap > second". > > Leap seconds are added periodically to adjust to irregularities in the > earth’s rotation in relation to Coordinated Universal Time (UTC), the > current reference for measuring time, in order to remain close to mean > solar time (UT1). A leap second was added most recently on 30 June 2015 > at 23:59:60 UTC. The proposal to suppress the leap second would have > made continuous reference time-scale available for all modern electronic > navigation and computerized systems to operate while eliminating the > need for specialized ad hoc time systems. > > The decision by WRC-15 calls for further studies regarding current and > potential future reference time-scales, including their impact and > applications. A report will be considered by the World > Radiocommunication Conference in 2023. Until then, UTC shall continue to > be applied as described in Recommendation ITU-R TF.460-6 > [https://www.itu.int/rec/R-REC-TF.460-6-200202-I/en] and as maintained > by the International Bureau of Weights and Measures (BIPM). > > WRC-15 also calls for reinforcing the links between ITU and the > International Bureau of Weights and Measures (BIPM). ITU would continue > to be responsible for the dissemination of time signals via > radiocommunication and BIPM for establishing and maintaining the second > of the International System of Units (SI) and its dissemination through > the reference time scale. > > Studies will be coordinated by ITU along with international > organizations such as the International Maritime Organization (IMO), the > International Civil Aviation Organization (ICAO), the General Conference > on Weights and Measures (CGPM), the International Committee for Weights > and Measures (CIPM), the International Bureau of Weights and Measures > (BIPM), the International Earth Rotation and Reference Systems Service > (IERS), the International Union of Geodesy and Geophysics (IUGG), the > International Union of Radio Science (URSI), the International > Organization for Standardization (ISO), the World Meteorological > Organization (WMO), and the International Astronomical Union (IAU). > > "Modern society is increasingly dependent on accurate timekeeping," said > ITU Secretary-General Houlin Zhao. "ITU is responsible for disseminating > time signals by both wired communications and by different > radiocommunication services, both space and terrestrial, which are > critical for all areas of human activity." > > "The worldwide coordination of time signals is critical for the > functioning and reliability of systems that depend on time," said > Francois Rancy, Director of the ITU Radiocommunication Bureau. "ITU will > continue to work with international organizations, industry and user > groups towards providing coherent advice on current and potential future > reference time-scales." > > Source: ITU Press Release, > http://www.itu.int/net/pressoffice/press_releases/2015/53.aspx > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
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