Winnecke 4 (also known as Messier Object 40 or WNC 4) is a double star in the constellation Ursa Major. It was discovered by Charles Messier in 1764 while he was searching for a nebula that had been reported in the area by Johann Hevelius. Not seeing any nebulae, Messier catalogued this double star instead. It was subsequently rediscovered by Friedrich August Theodor Winnecke in 1863. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... The J2000. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Ursa Major (Ursa Maior in Latin) is a constellation visible throughout the year in the northern hemisphere. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... Table of all 110 Messier objects. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Double Star is a science fiction novel by Robert A. Heinlein. ... Ursa Major (Ursa Maior in Latin) is a constellation visible throughout the year in the northern hemisphere. ... Charles Messier Charles Messier (June 26, 1730 – (April 12, 1817) was a French astronomer who in 1774 published a catalogue of 45 deep sky objects such as nebulae and star clusters. ... 1764 was a leap year starting on Sunday (see link for calendar). ... Johannes Hevelius Johannes Hevelius or Johann Hewelke or Johannes Hewel (German) or Jan Heweliusz (Polish) (January 28, 1611-January 28, 1687) was an astronomer; called the founder of lunar topography. ... Friedrich August Theodor Winnecke (February 5, 1835 – December 3, 1897) was a German astronomer. ...

In 1991 the seperation between the components was measured at 51".7, an increase since Messier's time. The general consensus is that this is merely an optical double star rather than a physically connected system. This topic is about the astronomical phenomenon. ...

External links

• Messier 40, SEDS Messier pages