{"id":43,"date":"2011-04-02T01:44:14","date_gmt":"2011-04-02T01:44:14","guid":{"rendered":"https:\/\/astronomy.snjr.net\/blog\/?p=43"},"modified":"2011-05-03T01:35:57","modified_gmt":"2011-05-03T01:35:57","slug":"cassegrain-telescope","status":"publish","type":"post","link":"https:\/\/astronomy.snjr.net\/blog\/?p=43","title":{"rendered":"Cassegrain Telescope"},"content":{"rendered":"<p>Cassegrains are reflectors. \u00a0The classic Cassegrain has a parabolic (concave) primary mirror and a hyperbolic (convex) secondary mirror. \u00a0As you can see from the diagram below, the mirrors are aligned with the focal point behind the primary mirror (outside the telescope tube, at the end of the tube). \u00a0The light is gathered through the open end of the tube on the left and bounced off the primary mirror onto the secondary mirror. The secondary mirror then bounces the light to the central focal point, through a hole in the primary mirror at the right.<\/p>\n<div id=\"attachment_45\" style=\"width: 310px\" class=\"wp-caption alignnone\"><a href=\"https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain-Telescope.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-45\" class=\"size-medium wp-image-45\" title=\"Cassegrain Telescope\" src=\"https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain-Telescope-300x116.jpg\" alt=\"\" width=\"300\" height=\"116\" srcset=\"https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain-Telescope-300x116.jpg 300w, https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain-Telescope-1024x398.jpg 1024w, https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain-Telescope.jpg 1027w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><p id=\"caption-attachment-45\" class=\"wp-caption-text\">Cassegrain Telescope<\/p><\/div>\n<p>After some searching, I found the original description of the Cassegrain telescope in the 29 February 1672 issue of the <em>Journal des S\u00e7avans.* <\/em>Here&#8217;s the .pdf,\u00a0<a href=\"https:\/\/astronomy.snjr.net\/blog\/wp-content\/uploads\/2011\/04\/Cassegrain.pdf\">Cassegrain Telescope, 1672 Journal of S\u00e7avans<\/a>, courtesy of Gallica\u00a0Biblioth\u00e8que Num\u00e9rique.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Cassegrains are reflectors. \u00a0The classic Cassegrain has a parabolic (concave) primary mirror and a hyperbolic (convex) secondary mirror. \u00a0As you can see from the diagram below, the mirrors are aligned with the focal point behind the primary mirror (outside the telescope tube, at the end of the tube). \u00a0The light is gathered through the open [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7,6,5],"tags":[],"class_list":["post-43","post","type-post","status-publish","format-standard","hentry","category-instruments","category-telescopes","category-terminology"],"_links":{"self":[{"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/43","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=43"}],"version-history":[{"count":0,"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/43\/revisions"}],"wp:attachment":[{"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=43"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=43"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/astronomy.snjr.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=43"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}