IERS Reference Meridian and the Airy transit circle is that the observations with the transit circle were based on the local vertical, while the IERS...

Greenwich meridian was the international standard prime meridian, used worldwide for timekeeping and navigation. The modern standard, the IERS Reference Meridian...

prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard. A prime meridian for...

services of IERS are at the Paris Observatory. UT1 is the non-uniform time defined based on the Earth's rotation. It defined the IERS Reference Meridian, the...

meridian (currently, the IERS Reference Meridian). In other words, it is a line of longitude. The position of a point along the meridian is given by that longitude...

second of mean solar time (such as UT1) at 0° longitude, (at the IERS Reference Meridian). The mean solar day is slightly longer than 86,400 SI seconds...

prime meridian on any planet or moon For most of the 20th century on Earth, the prime meridian (Greenwich) IERS Reference Meridian, the modern reference meridian...

at the northernmost part of Earth. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway (Nordland...

The WGS 84 meridian of zero longitude is the IERS Reference Meridian, 5.3 arc seconds or 102 metres (335 ft) east of the Greenwich meridian at the latitude...

Prime Meridians that have been used, are used, or are proposed Greenwich Meridian established by the International Meridian Conference IERS Reference Meridian...