{"id":323,"date":"2020-10-22T11:09:08","date_gmt":"2020-10-22T11:09:08","guid":{"rendered":"https:\/\/maritimesa.org\/nautical-science-grade-11\/?p=323"},"modified":"2020-10-22T11:16:45","modified_gmt":"2020-10-22T11:16:45","slug":"observed-to-true-altitude","status":"publish","type":"post","link":"https:\/\/maritimesa.org\/nautical-science-grade-11\/2020\/10\/22\/observed-to-true-altitude\/","title":{"rendered":"Observed to true altitude"},"content":{"rendered":"<p>When we take a sextant altitude of a heavenly body, we measure the angle between the body and the visible sea horizon as witnessed from the observer\u2019s position on the bridge of a vessel. (angle DOX in the diagram). This is referred to as the observed altitude. In converting it to a true altitude we need to change the observation position from the bridge of the vessel to the centre of the earth, the true altitude being angle RCX in the diagram.<\/p>\n<div id=\"attachment_86\" style=\"width: 910px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-86\" class=\"size-full wp-image-86\" src=\"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1.jpg\" alt=\"\" width=\"900\" height=\"720\" srcset=\"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1.jpg 900w, https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1-300x240.jpg 300w, https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1-768x614.jpg 768w, https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1-183x146.jpg 183w, https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1-50x40.jpg 50w, https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-content\/uploads\/sites\/6\/2020\/10\/11.1.5.2_fig_1-94x75.jpg 94w\" sizes=\"(max-width: 900px) 100vw, 900px\" \/><p id=\"caption-attachment-86\" class=\"wp-caption-text\">Observed altitude to true altitude.<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"<p>When we take a sextant altitude of a heavenly body, we measure the angle between the body and the visible sea horizon as witnessed from the observer\u2019s position on the bridge of a vessel. (angle DOX in the diagram). This is referred to as the observed altitude. In converting it [&hellip;]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,41,43],"tags":[],"class_list":["post-323","post","type-post","status-publish","format-standard","hentry","category-11-1-navigation","category-11-1-5-altitude-correction","category-11-1-5-2-observed-to-true-altitude"],"_links":{"self":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/posts\/323"}],"collection":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/comments?post=323"}],"version-history":[{"count":1,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/posts\/323\/revisions"}],"predecessor-version":[{"id":324,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/posts\/323\/revisions\/324"}],"wp:attachment":[{"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/media?parent=323"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/categories?post=323"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maritimesa.org\/nautical-science-grade-11\/wp-json\/wp\/v2\/tags?post=323"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}