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An equatorial mount is a mount for instruments that follows the rotation of the sky (celestial sphere) by having one rotational axis parallel to the Earth's axis of rotation.〔(【引用サイトリンク】 LAS MONTURAS )〕〔(【引用サイトリンク】 Observatorio ARVAL - Polar Alignment for Meade LXD55/75 Autostar telescopes )〕 This type of mount is used for astronomical telescopes and cameras. The advantage of an equatorial mount lies in its ability to allow the instrument attached to it to stay fixed on any object in the sky that has a diurnal motion by driving one axis at a constant speed. Such an arrangement is called a sidereal drive. ==Astronomical telescope mounts== In astronomical telescope mounts, the equatorial axis (the ''right ascension'') is paired with a second perpendicular axis of motion (known as the ''declination''). The equatorial axis of the mount is often equipped with a motorized "''clock drive''", that rotates that axis one revolution every 23 hours and 56 minutes in exact sync with the apparent diurnal motion of the sky.〔(Turn left at Orion: a hundred night sky objects to see in a small telescope ... By Guy Consolmagno, Dan M. Davis, Karen Kotash Sepp, Anne Drogin, Mary Lynn Skirvin, page 204 )〕 They may also be equipped with setting circles to allow for the location of objects by their celestial coordinates. Equatorial mounts differ from mechanically simpler altazimuth mounts, which require variable speed motion around both axes to track a fixed object in the sky. Also, for astrophotography, the image does not rotate in the focal plane, as occurs with altazimuth mounts when they are guided to track the target's motion, unless a rotating erector prism or other field-derotator is installed. Equatorial telescope mounts come in many designs. In the last twenty years motorized tracking has increasingly been supplemented with computerized object location. There are two main types. Digital setting circles take a small computer with an object database that is attached to encoders. The computer monitors the telescope's position in the sky. The operator must push the telescope. Go-to systems use (in most cases) servo motors and the operator need not touch the instrument at all to change its position in the sky. The computers in these systems are typically either hand-held in a control "paddle" or supplied through an adjacent laptop computer which is also used to capture images from an electronic camera. The electronics of modern telescope systems often include a port for autoguiding. A special instrument tracks a star and makes adjustment in the telescope's position while photographing the sky. To do so the autoguider must be able to issue commands through the telescope's control system. These commands can compensate for very slight errors in the tracking performance, such as periodic error caused by the worm drive that makes the telescope move. In new observatory designs, equatorial mounts have been out of favor for decades in large-scale professional applications. Massive new instruments are most stable when mounted in an alt-azimuth (up down, side-to-side) configuration. Computerized tracking and field-derotation are not difficult to implement at the professional level. At the amateur level, however, equatorial mounts remain popular, particularly for astrophotography. === German equatorial mount === In the German equatorial mount,〔(【引用サイトリンク】 German and Fork Equatorial Mounts )〕 (sometimes called a "GEM" for short) the primary structure is a T-shape, where the lower bar is the ''right ascension'' axis (lower diagonal axis in image), and the upper bar is the ''declination'' axis (upper diagonal axis in image). The telescope is placed on one end of the declination axis (top left in image), and a suitable counterweight on other end of it (bottom right). The right ascension axis has bearings below the T-joint, that is, it is not supported above the declination axis. 抄文引用元・出典: フリー百科事典『 In the German equatorial mount,(【引用サイトリンク】 German and Fork Equatorial Mounts ) (sometimes called a "GEM" for short) the primary structure is a T-shape, where the lower bar is the ''right ascension'' axis (lower diagonal axis in image), and the upper bar is the ''declination'' axis (upper diagonal axis in image). The telescope is placed on one end of the declination axis (top left in image), and a suitable counterweight on other end of it (bottom right). The right ascension axis has bearings below the T-joint, that is, it is not supported above the declination axis.">ウィキペディア（Wikipedia）』 ■In the German equatorial mount,(【引用サイトリンク】 German and Fork Equatorial Mounts ) (sometimes called a "GEM" for short) the primary structure is a T-shape, where the lower bar is the ''right ascension'' axis (lower diagonal axis in image), and the upper bar is the ''declination'' axis (upper diagonal axis in image). The telescope is placed on one end of the declination axis (top left in image), and a suitable counterweight on other end of it (bottom right). The right ascension axis has bearings below the T-joint, that is, it is not supported above the declination axis.">ウィキペディアで「An equatorial mount is a mount for instruments that follows the rotation of the sky (celestial sphere) by having one rotational axis parallel to the Earth's axis of rotation.(【引用サイトリンク】 LAS MONTURAS )(【引用サイトリンク】 Observatorio ARVAL - Polar Alignment for Meade LXD55/75 Autostar telescopes ) This type of mount is used for astronomical telescopes and cameras. The advantage of an equatorial mount lies in its ability to allow the instrument attached to it to stay fixed on any object in the sky that has a diurnal motion by driving one axis at a constant speed. Such an arrangement is called a sidereal drive.==Astronomical telescope mounts==In astronomical telescope mounts, the equatorial axis (the ''right ascension'') is paired with a second perpendicular axis of motion (known as the ''declination''). The equatorial axis of the mount is often equipped with a motorized "''clock drive''", that rotates that axis one revolution every 23 hours and 56 minutes in exact sync with the apparent diurnal motion of the sky.(Turn left at Orion: a hundred night sky objects to see in a small telescope ... By Guy Consolmagno, Dan M. Davis, Karen Kotash Sepp, Anne Drogin, Mary Lynn Skirvin, page 204 ) They may also be equipped with setting circles to allow for the location of objects by their celestial coordinates. Equatorial mounts differ from mechanically simpler altazimuth mounts, which require variable speed motion around both axes to track a fixed object in the sky. Also, for astrophotography, the image does not rotate in the focal plane, as occurs with altazimuth mounts when they are guided to track the target's motion, unless a rotating erector prism or other field-derotator is installed.Equatorial telescope mounts come in many designs. In the last twenty years motorized tracking has increasingly been supplemented with computerized object location. There are two main types. Digital setting circles take a small computer with an object database that is attached to encoders. The computer monitors the telescope's position in the sky. The operator must push the telescope. Go-to systems use (in most cases) servo motors and the operator need not touch the instrument at all to change its position in the sky. The computers in these systems are typically either hand-held in a control "paddle" or supplied through an adjacent laptop computer which is also used to capture images from an electronic camera. The electronics of modern telescope systems often include a port for autoguiding. A special instrument tracks a star and makes adjustment in the telescope's position while photographing the sky. To do so the autoguider must be able to issue commands through the telescope's control system. These commands can compensate for very slight errors in the tracking performance, such as periodic error caused by the worm drive that makes the telescope move.In new observatory designs, equatorial mounts have been out of favor for decades in large-scale professional applications. Massive new instruments are most stable when mounted in an alt-azimuth (up down, side-to-side) configuration. Computerized tracking and field-derotation are not difficult to implement at the professional level. At the amateur level, however, equatorial mounts remain popular, particularly for astrophotography. === German equatorial mount === German equatorial mount to suit -->In the German equatorial mount,(【引用サイトリンク】 German and Fork Equatorial Mounts ) (sometimes called a "GEM" for short) the primary structure is a T-shape, where the lower bar is the ''right ascension'' axis (lower diagonal axis in image), and the upper bar is the ''declination'' axis (upper diagonal axis in image). The telescope is placed on one end of the declination axis (top left in image), and a suitable counterweight on other end of it (bottom right). The right ascension axis has bearings below the T-joint, that is, it is not supported above the declination axis.」の詳細全文を読む スポンサード リンク
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