Hello!! It's Joseph

  Joey   Cloudynights Openastro With android support IPARCOS Github   Github io   Indi forum

The global astronomical telescope market size was valued at USD 333.6 million in 2020 and is projected to reach USD 455.9 million by 2028, growing at a CAGR of 4.0% during the forecast period (2021-2028).   The global astronomical telescope market is witnessing significant growth, driven by the increasing interest in astronomy, space exploration, and astrophotography. Astronomical telescopes are essential tools for observing the night sky, planets, stars, and galaxies. Smart telescope market : Better description should be EAA computerised telescope Prototype BOM cost: 1700 RMB est 定價: 犧牲利潤換市佔, 售價 USD399 時機：剛巧在2024日全蝕前推出。 但有點rush, 很多 配件eg narrowband filter(OIII30nm, Ha20nm), solar filter ( solarlite ND5)後來補加 宣傳手法誇張失實 exaggerated propaganda，不同以往的 technical marketing , 以下此圖盡現： 相中60mm f6 full frame fov vs seestar 50mm f5 6.46mm fov telescope  相中AZGTI payload 5 kg vs seestar < 2.5 kg 內置的UV-IR filter 會 cut off 紅外端的光譜，浪費掉IMX462 的 800nm 近紅外敏感度NIR sensitivity。 相中5 bay filter wheel vs 3 bay f

 F rom Kari Brown, aka kbrown73 cloudynights    OAG focuser: SGL Kari Brown's website   gitlab   robert brown: myfocuser pro 2 , arduino based sourceforge   github indi forum , indi support  OSHW

  cassegrain telescope on cloudynights , which is also on S&T Oct 2006 from mike lockwood : given: R2(sec ROC) = 47.35" secondary distance to primary focal point p (circled in orange) = 15.72" conic of primary = -1 (parabola) conic of secondary = -4 (hyperbola)   appendix on CassDesign: Unvignetted Field Width at Cass focus is the dimension in the user-chosen units. P = distance of secondary vertex inside primary focus P' = distance from secondary vertex to final Cass focus The back working distance (BWD) is from the primary mirror vertex to Cass focus. It is also P' - SEP, where SEP is the vertex-to-vertex mirror separation. BWD must be personally chosen to include enough distance for the primary mirror thickness, the primary support system, the back plate thickness, the optical path length through any fold optics, the height of the focuser, and the desired distance from the top of the focuser (maybe at midpoint travel setting) to the focal plane. BWD is entirel

This is a spot diagram of what an e.g. 8 inch F8 Ritchey Chretien is supposed to perform like off axis. It's from page 68 of Telescope Optics by Rutten and Venrooij.  I see no coma at all but there is the strongest Field Curvature of any Cassegrain design, (without the ACF coating), plus some astigmatism, but the star images are pretty round a long way off axis (that's why professional astronomers use RC's, since they like to measure the Star images and round images are easier to measure).   cloudynights Chungblog  

Announcement 2023年3月，深圳西涌获得国际暗夜社区认证，这是国内首个国际暗夜社区 Improvement  西涌 社区的平均光污染等级为4级(尚可)，这个数字在深圳中心区福田区为8-9级(极强)。在这个基础上，朱进认为 西 涌 要成为暗夜社区在理论上是存在可能性的。 梅林介绍，打造暗夜社区，需要对暗夜社区和社区周边的区域，在特定时间段对灯光进行一定程度的管控。他强调，并不需要对灯光包括广告牌灯光做一刀切，而是给路灯罩上盖子，只照射地面和平面的方向;渔船夜间的灯光也可以不开那么亮。 朱进补充道，要合理规划路灯数量和密度，在保证安全的情况下，关掉可以不开的灯;降低灯光的功率以及对颜色做一定管理;此外，可以要求居民家中使用较厚的窗帘，天黑后室内的光线不要漏到户外。 同时，朱进认为：“暗夜社区的相关制度需要在大于社区的政府层面，以比较正式的规章制度的形式颁布和执行。可以针对核心保护区和距离核心保护区不同距离范围，制定不同标准。同时，还可以在时间上做特殊的和一般性的要求。” Light pollution map： Darkmap.cn: 預約參觀: 深圳天文台  公開平台 weibo 交通 天文觀測信號（一站式資訊 when+what+how): 不再談bortle scale 了 深圳氣象局 Reference Bilibili Darksky Sznews  旅遊指南

 Both are dobsonian. Metal vs wood: Both are 16" F/4.5,typ 13 kg Left: Explore Scientific 30kg mirror box + 10 kg rocker = 40kg Right: 18-20 kg mirror box + 10-12 kg (rocker + UTA) = 28 to 32 kg est. COG is higher reference: sumerian alkaid Alan xmission DS4 JWST back plane  is made from prepreg comprising carbon fiber provided by Toray Advanced Composites and cyanate ester resin from Hexcel (Stamford, Conn., U.S.). Support payload of more than 300% its own weight.  

A newtonian binoscope. 200mm primary mirror x2 Secondary and tertiary diagonal mirrors 20kg 3D printing from Robert Asumendi Phys , all3dp   focuser and tiertary mirror: ultralight version, 7 kg. watch out for OSP2023:   1 please note that, due to larger secondary mirror(67mm sec) being used,  central obstruction of 32.5%, will be 4.5% bigger than conventional newtonians(56mm sec) 2 how to attach a finder scope, leaves something to be desired. Maybe a smartphone with a star map app can do. reference: First prototype in OSP2018 indiegogo Facebook   Theawesomer   Youtube podcast

Ross Sackett Moonsilver series Moonlight IV: 18" f/4.3, 63 lbs Litescope , woden   litescope dot net ,  astromart Single arm  CSA telescope on hkastroforum. YouTube   Zingaro Martin Bruckner Quints   Roel: Laurent   Dreamscope   Wah!  25kg Dbpeckhan Another CF telescope   8" 3D printed OTA: 8 lbs Honeycomb 16” mirror, 50mm thick, 5.2 kg Reference: Cloudynights   CN: How much your dob weigh Serrurier truss   Tensigrity   OSP2017   Bend strength  , calculator    Truss calculator Beamguru CF vs AL : half the weight, but 6 times the cost Tripods  

 from webgeocalc DistanceFinder Aphelion of 2023: 2023-07-06 20:06:38.435260 UTC similarly, periphelion of 2023: 2023-01-04 16:17:27.532134 UTC IMCCE: slowest orbital speed is on aphelion? de-mythstified:  According to Kepler's laws , AMS >> Yes.  But by observation >> Sort of: 10 July in 2023(sqrt(dx^2+dy^2)): IERS dx: dy: 60135 is modified Julian date,  Keisan   Solar Distance can be found by JPL SSD , reading AD (Apoapsis distance) column, time is in TDB   Reference: IMCCE perihelion 2023 IMCCE aphelion 2023   earthscience stackexchange and python script( less than 15 sec of deviation)  Jay Tanner PHP GSFC Earth fact sheet Better than 1 minute resolution  , UTC2TDB  online convertor