Galactic coordinate system

The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way galaxy, the fundamental plane parallel to an approximation of the galactic plane but offset to its north. It uses the right-handed convention, meaning that coordinates are positive toward the north and toward the east in the fundamental plane. Longitude measures the angular distance of an object eastward along the galactic equator from the galactic center. Analogous to terrestrial longitude, galactic longitude is measured in degrees. Latitude measures the angle of an object north or south of the galactic equator as viewed from Earth. For example, the north galactic pole has a latitude of +90°. Analogous to terrestrial latitude, galactic latitude is measured in degrees; the first galactic coordinate system was used by William Herschel in 1785. A number of different coordinate systems, each differing by a few degrees, were used until 1932, when Lund Observatory assembled a set of conversion tables that defined a standard galactic coordinate system based on a galactic north pole at RA 12h 40m, dec +28° and a 0° longitude at the point where the galactic plane and equatorial plane intersected.

In 1958, the International Astronomical Union defined the galactic coordinate system in reference to radio observations of galactic neutral hydrogen through the hydrogen line, changing the definition of the Galactic longitude by 32° and the latitude by 1.5°. In the equatorial coordinate system, for equinox and equator of 1950.0, the north galactic pole is defined at right ascension 12h 49m, declination +27.4°, in the constellation Coma Berenices, with a probable error of ±0.1°. Longitude 0° is the great semicircle that originates from this point along the line in position angle 123° with respect to the equatorial pole; the galactic longitude increases in the same direction as right ascension. Galactic latitude is positive towards the north galactic pole, with a plane passing through the Sun and parallel to the galactic equator being 0°, whilst the poles are ±90°. Based on this definition, the galactic poles and equator can be found from spherical trigonometry and can be precessed to other epochs.

The IAU recommended that during the transition period from the old, pre-1958 system to the new, the old longitude and latitude should be designated lI and bI while the new should be designated lII and bII. This convention is seen. Radio source Sagittarius A*, the best physical marker of the true galactic center, is located at 17h 45m 40.0409s, −29° 00′ 28.118″. Rounded to the same number of digits as the table, 17h 45.7m, −29.01°, there is an offset of about 0.07° from the defined coordinate center, well within the 1958 error estimate of ±0.1°. Due to the Sun's position, which lies 56.75±6.20 ly north of the midplane, the heliocentric definition adopted by the IAU, the galactic coordinates of Sgr A* are latitude +0° 07′ 12″ south, longitude 0° 04′ 06″. Since as defined the galactic coordinate system does not rotate with time, Sgr A* is decreasing in longitude at the rate of galactic rotation at the sun, Ω 5.7 milliarcseconds per year. An object's location expressed in the equatorial coordinate system can be transformed into the galactic coordinate system.

In these equations, α is right ascension, δ is declination. NGP refers to the coordinate values of the north galactic pole and NCP to those of the north celestial pole. Sin ⁡ = sin ⁡ sin ⁡ + cos ⁡ cos ⁡ cos ⁡ cos ⁡ sin ⁡ = cos ⁡ sin ⁡ cos ⁡ cos ⁡ = cos ⁡ sin ⁡ − sin ⁡ cos ⁡ cos ⁡ {\displaystyle {\begin\sin&=\sin\sin+\cos\cos(\delt

Dr. James Bell House

The Dr. James Bell House known as the Bell-Williams House, is a historic home located at 1822 E. 89th Street in Cleveland, Ohio, in the United States. Designed by noted local architect George J. Hardway for Dr. James Bell, it was completed in 1901; the home is a prime example of the Cleveland-area reaction at the end of the 19th century against high Victorian architecture, utilizing elements of Richardsonian Romanesque architecture to create a individualized, severe style. The home was added to the National Register of Historic Places on October 16, 1986; the home is part of the East 89th Street Historic District, added to the National Register of Historic Places on May 26, 1988. James Richard Bell was a prominent dentist in Cleveland in the late early 20th centuries. In 1900, he commissioned noted local architect George J. Hardway to design a large residence on E. 89th Street in the southeast quadrant of the Hough neighborhood, one of the city's oldest settled areas and which at that time was inhabited by white, middle-class and upper-middle-class residents.

The block on which Bell chose to build was built up with a number of large residences over the past 30 years, ranging in style from Italianate to elaborate Queen Anne style. The elaborate embellishments of Victorian architecture had fallen out of favor with homeowners and architects in northeast Ohio by the late 1890s, Bell and Hardway agreed on a home, simple to the point of being severe; the Bell House is Richardsonian Romanesque in style. However, it deviates from this style by featuring a contemporary massing and relying on plain exterior walls; the three-story structure is constructed of brick. The front of the house is square, with an east-facing gable, a single dormer on the south side, steep roof pitch; the third-floor windows are topped by round stone arches, with stone slabs constituting the lintel and sill of the first and second story windows. A rusticated stone porch with canopy provided the entrance to the house; the narrow-depth center section of the house features projecting polygonal bay windows on all three floors on the south side.

This projection is topped by a hip-end roof. The north side of the center section is a triple-wide dormer or gable facing north, with a gable roof; the rear of the building, about as large as the front section, returns to the square plan, although it features two dormers on the north side and none on the south. The home had 12 rooms, four baths, a third-floor ballroom. By the 1970s, the ballroom had been divided and the house now had a total of 21 rooms. Bell occupied the home until his death in 1912; the home was bequeathed to Anna Roeder Bell. She died in 1940, bequeathed the home to her daughter, Frieda Meriam. Mrs. Meriam died in 1942, the home was sold to John A. Smith in 1943. By 1947, the home belonged to the Sabo family, by 1948 the Jaskell family. By 1956, it was owned by Enoch Spence, who sold it by 1961 to Harold C. Scheunemann, who in turn sold it to Raymond Beedlow by 1966; the Hough neighborhood became an overwhelmingly poor African American area by 1960. In May 1968, the mansion was purchased by the Berry Foundation.

It became the home of the Martin Luther King Residential Youth House, a residential home for troubled black youth. The ballroom was turned into bedrooms about this time. In the early or mid 1970s, the youth house closed, the Lee Heights Community Church rented the structure for use by The Straight-up Half-Way House, a transitional residence for alcoholics and drug addicts; the Berry Foundation sold the house in 1979 to Margaret J. Williams; because it exemplifies the local architectural reaction to the excesses of Victorian architecture, the house was added to the National Register of Historic Places on October 16, 1986. It was named a Cleveland Landmark by the Cleveland Landmarks Commission, under the name Bell-Williams House. Media related to James Bell House at Wikimedia Commons


Shamdarra or Shamdharra is a village and union council of the Mansehra District in the Khyber Pakhtunkhwa province of Pakistan. It is located in the north of the district. About 58% of the population of the Shamdharra area are engaged in bucolic occupations, such as agriculture/cultivation, animal husbandry, livestock management and forestry; the rest of the population work as expatriates in other locations in Pakistan, or abroad. Others are engaged in local medium-scale businesses; the main languages of the region are Pushto followed by Gojri and others. The main ethnic groups are: Pathans, Awan and Sayyids, it is most diverse town in the area, which accepts all the people from different customs and backgrounds