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  Google maps   The Qinghai Observatory began construction in 1982. It is located on the Qinghai-Tibet Plateau, Delingha, the third largest city in Qinghai Province. It is 3,200 meters above sea level, 97°33′.6 east longitude and 37°22′.4 north latitude. Qinghai Station is also known as Delingha Astronomical Observatory. 德令哈市，蒙古語全稱「阿里騰德令哈」，意為「金色的世界」 Saishiteng mountain 塞什騰山 possible design: lenseless schmidt   baker camera   hyper subprime cam in subaru telescope Tomo-e Gozen telescope would be a good reference or comparison 0.8米的 行星大气光谱望远镜 (PAST) phys  30m telescope  6-8 m EAST （2024-2030） 北京大學 24 hour sky view   Nature    instrumentapparatus   intechopen astelco  ALTAZ robot telescope.  LCO   CCTV WFST  墨子大视场巡天望远镜是我国开造的新一代天文望远镜，其主镜的口径达2.5米，设计上采用了国际领先的主焦光学模式，可提供大视场、高精度和宽波段的巡天能力，其感光元件是大面阵7.2亿像素拼接CCD探测器，由9片CCD290-99芯片拼接而成，成像阵列达到9K x 9K，像素大小为10微米，成像面积达到92.2毫米 × 92.4毫米，具有超低噪声读出能力，在500Kpix/s读出速率下读出噪声可小于5个电子。 Youtub...

 Jetpack  VL4 libargus  e-con API programming guide

  This is a case of  "right angled triangle in a  semi-circle" or Thales' theorem.  and a case of Ptolemy's theorem , pentagon in a circle    b x b = a x a + a x b   a x d = 2 x b x c   Van Ceulen goes on the doubling the sides from pentagon, to decagon(10 sides) and so on ptolemy's theorem edwardworth maa

    comparison of convergence of different methods: pi314 github octapi in python keisan casio calculator  hpmuseum

Ludolph van Ceulen (1540-1610), a danish mathematician and fencing teacher who spent around 25 years of his life calculating Pi to 35 decimal places. The engraving on the title page is the same one used for the Dutch original. Notice that below the portrait of Van Ceulen is a circle with diameter of 1020. Along the top and bottom semicircles is printed “314159265358979323846 te cort” (too short) and “314159265358979323847 te lanck” (too long). These bounds for π were the best ones available when Vanden Circkel was published in 1596. Later, Van Ceulen determined π to 35 decimal places. As evidence of the importance of Van Ceulen’s work, π has been known as “Ludolph’s number” or the “Ludolphine number”, especially in Germany and the Netherlands. Below on page 5, starting with a square inscribed in a circle with diameter 2, is a sequence of line segments constructed with increasing lengths  The line segments are actually lines drawn across the polygon(not completely shown here)in th...

  micro observatory

  A fusion experiment at the world’s biggest laser facility released 1.3 million joules of energy, coming close to a break-even point known as ignition, where fusion begins to release more energy than required to detonate it. Reaching ignition would strengthen hopes that fusion could one day serve as a clean, plentiful energy source, By pummeling a tiny capsule with lasers at the National Ignition Facility, or NIF, at Lawrence Livermore National Laboratory in California, scientists triggered fusion reactions that churned out more than 10 quadrillion watts of power over 100 trillionths of a second. In all, the experiment, performed August 8 2021, released about 70 percent of the energy of the laser light used to set off the fusion reactions, putting the facility much closer to ignition than ever before.  magnetic-inertial confinement fusion sciencenews .  Science alert 12 Dec 2022 . On December 5, a team at LLNL’s National Ignition Facility (NIF)  conducted the first ...

 shallowsky   ring moon systems github  

cordierite MgO–Al2O3–SiO2s:   characteristics: Minimal temperature deformation due to unique material composition with an extremely low thermal expansion rate Approx. 70% weight reduction when compared to low CTE glass* with a slim ribbed structure design featuring high rigidity Rapid process time even for complex designs due to good machinability examples:   kyocera  researchgate

  instructable   MATP 's howto this Sony S2 ( same as normal  microusb ) port ( sony called it multi terminal socket).  From skyswitches :  these models are supported by gphoto too ian morison with LE NR turn off trick: however for A5000 and A5100, when in shutter priority, LE NR (Long Exposure Noise Reduction) cannot be turned off if exposure is more than 1 sec   : workaround: .......Well, not entirely true. I agree it is totally inconvenient but there is a way of setting A5000 to BULB mode without Noise reduction. 1. Set the camera to M mode for manual exposure shooting. 2. Set the camera for continuous bracketing at "BRK C 0.3ev". It is a setting available in the bracketing menu. but BULB will not be available then. But you can set exposure as long as 30" 3. Rotate the control wheel for setting exposure time to BULB. 4. Use wired remote for better stability. I purchased NEEWER and it has a mechanism holding the button until released.  stargazers...

For ASI183 From Shiraz, original Excel from Steven Bellavia: here   revised version: here  in google drive comparison of different approach for ASI 1600:   Steven has made the excel for ASI071, ASI1600, ASI183, ASI2600, ASI294, ASI533, ASI6200  with some minor adjustments, these should be useable on QHY, Toucam and other alternatives cloudynights cloudynights 2    LHiRES ESO VISTA Exposure calculator   Gemini   howard group    mirametric online SNR   calculator

 pixel scale: under sampling, image appears jagged or blocky 2.393 arcsec / pixel: original photo here over sampling 0.131 arcsec / pixel: original photo here   The original photo is downsized to 12.5% for easier comparison. Stars are supposed to be bloated, but this is not obvious. same image, without downsizing but cropped:  The stars surely are spiky, but are they bloated or not? As nowadays, stacking or lucky imaging(low arcsec per pixel), together with powerful post-processing techniques, over-sampling seems to be less of an issue IMHO, good focus and tracking, long cumulative exposures, high signal to noise ratio, good post processing is more important for 0.3 arsec / pixel scale, usually it is use with large aperture (> 1m) telescope in observatory skyandtelescope telescopes available to UK astronomers

  1766 John Harrison, first nautical almanac  lunar distance   history of longitude .  1730-1761 marine chronometer invented by John Harrison  Making of   H4 Wooden regulator longcase  , most accurate clock for 150 years  Timeline

  book on Amazon software implementation: go by Sonia Keys python by Pavolgaj  pymeeus in github pyplanets in github , and in pypi AA+ , from P J Naughter in C++, download link , base on Meeus, Lunar Ephemeris ELP2000 VSOP87 , VSOP2013 and more. PJ's wordpress OTOH javascript on NASA Fred Espanak eclipse website Meeus has many other interesting books too, eg Mathematical astronomical morsels series and Five Millennium catalog of solar eclipse catalog -1999 to 3000 Stephen Wolfram  , NDSolve and solar eclipse , RSS   Iris observatory, France  

 the proper name is NIR cutoff or blocking filter   first optical LPF(LPF1) is anti-aliasing filter ( to reduce Moire effect) ( can be 2 glasses) and where dust removal piezo is attached to IR cut filter or ICF( sometimes called LPF2) is the filter to be replaced for IR conversion types of IR cut filters: transmissive (left) and reflective (right). The transmissive type is also commonly called blue glass. The top 2 photo is taken directly over the filters, and bottom photo taken slightly slanted common ICF are BG38 ( QB21) and BG39 (QB39) Schott BG18 spec S8612   BG40   and some others in order to do infrared photography, it is needed to replace this IR cut filter with a IR band pass filter: Eg GG420(JB420) 420nm to >2500nm or BCF700 400 to 710 nm note the difference of  Ha increase nebulosity bright stars blur colour doped filter (old) vs sputtered interfering filter :   The transition from blocking of light to transmission of light is lazy with color...