# Angular+distance

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**Reflecting instrument**— Reflecting instruments are those that use mirrors to enhance their ability to make measurements. In particular, the use of mirrors permits one to observe two objects simultaneously while measuring the angular distance between the objects. While… …72

**Navigation**— This article is about determination of position and direction on or above the surface of the earth. For other uses, see Navigation (disambiguation). Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. Navigation is the… …73

**Sagnac effect**— The Sagnac effect (also called Sagnac Interference), named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called ring interferometry …74

**Binary star**— For the hip hop group, see Binary Star (band). Hubble image of the …75

**Meridian circle**— Groombridge transit circle of 1806 The meridian circle, transit circle, or transit telescope is an instrument for observing the time of stars passing the meridian, at the same time measuring its angular distance from the zenith. The idea of… …76

**Hindu calendar**— The Hindu calendar used in ancient times has undergone many changes in the process of regionalization, and today there are several regional Indian calendars, as well as an Indian national calendar. Most of these calendars are inherited from a… …77

**Cosine similarity**— is a measure of similarity between two vectors by measuring the cosine of the angle between them. The cosine of 0 is 1, and less than 1 for any other angle. The cosine of the angle between two vectors thus determines whether two vectors are… …78

**hour angle**— noun 1. the angular distance along the celestial equator from the observer s meridian to the hour circle of a given celestial body (Freq. 1) • Hypernyms: ↑distance 2. (astronomy) the angular distance of a celestial point measured westward along… …79

**Altair**— This article is about the star in the constellation Aquila. For other uses, see Altair (disambiguation). Altair …80

**Parsec**— For other uses, see Parsec (disambiguation). 1 parsec = SI units 30.857×10^12 km 30.857×10^15 m Astronomical units 206.26× …