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Universal Time (UT or UT1) is a time standard based on Earth's rotation. While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation ...
- DUT1
DUT1 (sometimes also written DUT) is a time correction equal...
- DUT1
Coordinated Universal Time ( UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communication, navigation, scientific research, and commerce.
世界时是以 地球自转 为基准得到的时间尺度，其精度受到地球自转不均匀变化和 极移 的影响，为了解决这种影响，1955年 国际天文联合会 定义了 UT0 、 UT1 和 UT2 三个系统： UT0系统是由一个天文台的天文观测直接测定的世界时，没有考虑极移造成的天文台地理坐标变化。 该系统曾长期被认为是稳定均匀的时间计量系统，得到过广泛应用。 UT1系统是在UT0的基础上加入了极移改正 Δλ ，修正地軸擺動的影響。 UT1是目前使用的世界时标准。 被作为目前世界民用时间标准 UTC 在增减 闰秒 时的参照标准。 UT2系统是UT1的平滑处理版本，在UT1基础上加入了地球自转速率的季节性改正 ΔT 。 它们之间的关系可以表示为： UT1 = UT0 + Δλ. UT2 = UT1 + ΔT. 参看
Universal Time (UT) is a solar time standard that reflects the average speed of the Earth's rotation. Learn about the different versions of UT, such as UT1, UT2, and UT0, and how they are measured by the stars and radio telescopes.
Universal Time (UT1): Also known as astronomical time or solar time, it refers to the Earth's rotation. It is used to compare the pace provided by TAI with the actual length of a day on Earth. UT Started in 1884. Universal Time (UT) was created at the International Meridian Conference in 1884.
Mar 22, 2023 · A user asks how UT1, the time based on Earth's rotation, is measured and calculated. Other users provide references and links to explain the concepts of celestial coordinates, Earth orientation, and time scales.
