跳到主要內容

窥幾

kknews:


測量： 星過中天 meridian transit . Ulugh beg的地下天文台同功能。


窺幾之制，長六尺，廣二尺，高倍之。下為趺，廣三寸，厚二寸，上跂廣四寸，厚如趺。以板為面，厚及寸，四隅為足，撐以斜木，務取正方。面中開明竅，長四尺，廣二寸。近竅兩旁一寸分畫為尺，內三寸刻為細分，下應圭面。几面上至梁心二十六尺，取以為準。窺限各各長二尺四寸，廣二寸，脊厚五分，兩刃斜閷，取其於幾面相符，着限兩端，厚廣各存二寸，銜入幾跂。俟星月正中，從幾下仰望，視表梁南北以為識，折取分寸中數，用為直景。又於遠方同日窺測取景數，以推星月高下也。

可視為現代重要光學測量optical astrometry 儀器eg carlsberg meridian telescope 的雛形。可惜當年還沒有改良發展下去。




Reference :

Baidu

Carlsberg meridian telescope wiki

Meridian circle 

Ulugh beg observatory 

標籤：

留言

張貼留言

這個網誌中的熱門文章

CMOS sensor trends and astrophotography, from amateur astronomers perspective

Nowadays, even in low light conditions, digital camera can quality pictures with higher ISO, noise and hot pixels have been gradually reduced. Sony has introduced back illumination process for consumer market. Sony BSI sensors evolved  from Exmor to now Exmor RS( stacked) technology. This stacked technology allows further chip size reduction, which has strong demands in smartphone camera market. Digital astrophotography is also benefited from such advances, utilising Back Side Illumination technology Exmor: Within the CMOS sensor, it outputs low-noise digital signals by "on-chip column AD conversion" and "dual noise reduction" to suppress noise in the first half of the process In low light conditions, when a wide aperture is desirable to collect as much light as possible. At apertures wider than f/2.0, back-illuminated Exmor R sensors are significantly more efficient at collecting light than conventional, front-illuminated sensor...
張貼留言
閱讀完整內容

ultrafast rendezvous to ISS

    14 Oct 2020,  being the first to use a new “ultrafast” rendezvous” scheme with the ISS. Following a flawless ascent to the correct orbit, Soyuz 2 .1a , Soyuz MS-17 caught up with the orbiting laboratory in only two orbits (three hours), halving the time it takes for crew to get to the Station.   The three space travelers of the Soyuz MS-17 mission launched on a six-month mission the International Space Station.  previous 3/4 orbit rendezvous: Soyuz MS-16 4 orbit rendezvous A three-orbit profile was deemed possible without major flight design changes after inauguration of the Soyuz 2-1A rocket that provides a much higher orbit injection accuracy than its predecessors and would allow the two correction maneuvers on Orbit #2 to be eliminated while the Automated Rendezvous Phase would still remain untouched. The deletion of the Orbit #2 maneuvers was expected to slightly tighten the already restrictive phase angle window from and upper limit of 30-35° to 25-28°...
張貼留言
閱讀完整內容

Scythians 斯泰基 塞種 西古提人

900 BC - 200 AD British museum   Tomb of scythe prince, Buktarma valley, 1200 masl, Google map Herodotus   絲路上的帝國 Biblegeography   哥羅西書 3：11  在此並不分希利尼人、猶太人、受割禮的、未受割禮的、化外人、 西古提人 、為奴的、自主的．惟有基督是包括一切、又住在各人之內。 塞種 塞迦  saka 史記漢書 西域傳： 塞種  ctext 昔匈奴破大月氏，大月氏西君大夏，而塞王南君罽賓。塞種分散，往往為數國。自疏勒以西北，休循、捐毒之屬，皆故 塞種 也。 匈奴列傳 Ctext ：塞王 《史記》在《大宛列傳》與《匈奴列傳》中， 詳細 記錄了中亞至天山一帶的塞種（塞王、塞地）狀況。例如，文中記載了月氏西破走塞王，導致塞人南遷越過懸度（今帕米爾高原及克什米爾一帶） Baike Genetic history   Genetics  Nih griffin  ? Scytho-Siberian  world 塞迦 saka  wiki Disappeared? Sarmatians （ 薩爾馬泰 ， 奄蔡 史記 ,  Aorsi ）and goths YouTube  
張貼留言
閱讀完整內容