{"id":2312,"date":"2020-02-19T17:38:18","date_gmt":"2020-02-19T20:38:18","guid":{"rendered":"http:\/\/scidev\/wordpress\/?page_id=2312"},"modified":"2024-06-19T17:12:06","modified_gmt":"2024-06-19T21:12:06","slug":"the-telescope","status":"publish","type":"page","link":"https:\/\/www.apex-telescope.org\/ns\/observing\/the-telescope\/","title":{"rendered":"The telescope"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"857\" src=\"http:\/\/www.apex-telescope.org\/ns\/wp-content\/uploads\/2020\/06\/apex_non_stop-cc.jpg\" alt=\"\" class=\"wp-image-2905\"\/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Reference paper<\/h3>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>The Atacama Pathfinder EXperiment (APEX) \u2013 a new submillimeter facility for southern skies. <\/p><cite><em>R. G\u00fcsten,&nbsp;L.-\u00c5. Nyman,&nbsp;P. Schilke,&nbsp;K. Menten,&nbsp;C. Cesarsky&nbsp;and&nbsp;R. Booth, <\/em><a rel=\"noreferrer noopener\" href=\"https:\/\/www.aanda.org\/articles\/aa\/abs\/2006\/29\/aa5420-06\/aa5420-06.html\" target=\"_blank\">Astronomy and Astrophysics, (2006), Volume 454, Number 2, L13-L16<\/a>.<\/cite><\/blockquote>\n\n\n\n<div class=\"wp-block-ugb-icon-list ugb-icon-list ugb-icon--icon-arrow ugb-3e79a83 ugb-icon-list--v2 ugb-main-block\"><style>.ugb-3e79a83 li::before{background-image:url('data:image\/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAxOTQgMTk0IiBzdHlsZT0iZmlsbDogIzAwZDA4NCAhaW1wb3J0YW50OyBjb2xvcjogIzAwZDA4NCAhaW1wb3J0YW50Ij48cGF0aCBkPSJNOTYuOSAyYy01Mi40IDAtOTUgNDIuNi05NSA5NXM0Mi42IDk1IDk1IDk1IDk1LTQyLjYgOTUtOTUtNDIuNi05NS05NS05NXpNNzguMiAxNTAuNGwtMTAuNi0xMC42TDExMC4zIDk3IDY3LjYgNTQuMmwxMC42LTEwLjZMMTMxLjUgOTdsLTUzLjMgNTMuNHoiIGZpbGw9IiMwMGQwODQiIHN0cm9rZT0iIzAwZDA4NCIgc3R5bGU9ImZpbGw6IHJnYigwLCAyMDgsIDEzMik7IHN0cm9rZTogcmdiKDAsIDIwOCwgMTMyKTsiLz48L3N2Zz4=')}.ugb-3e79a83.ugb-icon-list ul{columns:1}<\/style><div class=\"ugb-inner-block\"><div class=\"ugb-block-content\"><ul><li><a href=\"#factsheet\">Fact sheet<\/a><\/li><li><a href=\"#wobbler\">Wobbling secondary<\/a><\/li><li><a href=\"#efficiencies\">Telescope efficiencies<\/a><\/li><\/ul><\/div><\/div><\/div>\n\n\n\n<a id=\"factsheet\"><\/a>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<div style=\"height:60px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Fact sheet<\/h3>\n\n\n\n<figure class=\"wp-block-table aligncenter is-style-stripes\"><table><tbody><tr><td class=\"has-text-align-left\" data-align=\"left\"><br>Location<br><\/td><td class=\"has-text-align-left\" data-align=\"left\">Llano de Chajnantor. 50 km east of San Pedro de Atacama, Northern Chile<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Geodetic <br>Coordinates<sup>1<\/sup><\/td><td class=\"has-text-align-left\" data-align=\"left\">Latitude: 23\u00ba 00&#8242; 20&#8243;.8037 South<br>Longitude: 67\u00ba 45&#8242; 32&#8243;.9035 West<br>Altitude: 5104.47 m<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Geocentric coordinates (ITRF2005)<sup>1<\/sup><\/td><td class=\"has-text-align-left\" data-align=\"left\">X : 2225039.5297 m<br>Y: -5441197.6292 m<br>Z: -2479303.3597 m<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Main reflector<\/td><td class=\"has-text-align-left\" data-align=\"left\">Diameter: 12 m<br>264 aluminum panels with an average panel surface r.m.s. of 5 \u03bcm.<br>Full surface accuracy:  &lt; 15 \u03bcm r.m.s.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Secondary reflector<\/td><td class=\"has-text-align-left\" data-align=\"left\">Diameter: 0.75 m. <br>Hyperboloidal Aluminum<br>Polished to an average surface r.m.s. of 2 \u03bcm.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Manufacturer<\/td><td class=\"has-text-align-left\" data-align=\"left\">Vertex Antennentechnik<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Mass<\/td><td class=\"has-text-align-left\" data-align=\"left\">125,000 Kg<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Mounting <\/td><td class=\"has-text-align-left\" data-align=\"left\">Alt-azimuthal<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Primary focal length<\/td><td class=\"has-text-align-left\" data-align=\"left\">4.8 m<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Cassegrain focal ratio f\/D<\/td><td class=\"has-text-align-left\" data-align=\"left\">8<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Beam width<\/td><td class=\"has-text-align-left\" data-align=\"left\">7.\u20338 \u00d7 (800 \/ f [GHz])<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Pointing accuracy (r.m.s.)<\/td><td class=\"has-text-align-left\" data-align=\"left\">&lt; 2\u2033 all over the sky<br>Pointing accuracy on track, 0.\u20336<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Receiver cabins<\/td><td class=\"has-text-align-left\" data-align=\"left\">2 Nasmyth (A,B) + 1 Cassegrain (C)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><sup>1<\/sup> Coordinates measured as described in <a href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2015A%26A...581A..32W\/abstract\" target=\"_blank\" rel=\"noreferrer noopener\" aria-label=\"Wagner at al. 2015, A&amp;A, 581, A32 (opens in a new tab)\">Wagner at al. 2015, A&amp;A, 581, A32<\/a>.<\/p>\n\n\n\n<a id=\"wobbler\"><\/a>\n\n\n\n<div style=\"height:60px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Wobbling secondary<\/h3>\n\n\n\n<p>In 2007 the static subreflector was successfully replaced by a chopping subreflector. The wobbler, in the cases where it can be used, improves significantly the quality of the observations. By chopping quickly between two positions on sky (the &#8220;throw&#8221;), the observations will be less sensitive to time dependent instabilities in the receivers and the atmosphere. Currently, the wobbler can only be used together with the heterodyne receivers.<\/p>\n\n\n\n<p>In 2018 a new wobbling secondary was installed with a new and more advanced design. It has the following specifications:<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><tbody><tr><td class=\"has-text-align-left\" data-align=\"left\">Chop direction<\/td><td class=\"has-text-align-left\" data-align=\"left\">Cross elevation<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Wobbling rate (R)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Up to 2.0 Hz<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Maximum wobbling <br>throw (T<sub>max<\/sub>)<\/td><td class=\"has-text-align-left\" data-align=\"left\">T<sub>max<\/sub> = 300\u2033<br>maximum offset between the on and off positions is 600&#8243;\u00a0<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Duty cycle<\/td><td class=\"has-text-align-left\" data-align=\"left\">up to 96%  at 0.5 Hz<br>80-90%  at 1.0-1.5 Hz , throw 120&#8243;<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Operating modes<\/td><td class=\"has-text-align-left\" data-align=\"left\">Negative (left)<br>Positive (right)<br>Symmetric (left-right-left-right)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>When doing spectroscopic measurements with the heterodyne receivers it is recommended not to use&nbsp;<em>R<\/em> = 1.0 Hz as switching rate since it will be in resonance with the cryogenics pump cycle of 1 Hz. However, in the case of total power scans with the heterodyne receivers it is an advantage to use&nbsp;<em>R<\/em> = 1.0 Hz. The wobbling secondary is improving the quality of the observations when observing compact sources with extent less than twice the wobbler throw (up to 8-10 arc minutes). Typical sources where its use is beneficial are circumstellar envelopes, planets, molecular hot cores, and most galaxies.<\/p>\n\n\n\n<div style=\"height:60px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<a id=\"efficiencies\"><\/a>\n\n\n\n<h3 class=\"wp-block-heading\">Telescope efficiencies<\/h3>\n\n\n\n<p>We maintain a page with the <a href=\"http:\/\/www.apex-telescope.org\/telescope\/efficiency\/index.php\" target=\"_blank\" rel=\"noreferrer noopener\">antenna efficiencies<\/a> measured all over the years, based on cross-scans towards planets. You will need these to convert your antenna temperatures into physical units.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Reference paper The Atacama Pathfinder EXperiment (APEX) \u2013 a new submillimeter facility for southern skies. R. G\u00fcsten,&nbsp;L.-\u00c5. Nyman,&nbsp;P. Schilke,&nbsp;K. Menten,&nbsp;C. Cesarsky&nbsp;and&nbsp;R. Booth, Astronomy and Astrophysics, (2006), Volume 454, Number 2, L13-L16. Fact sheet Wobbling secondary Telescope efficiencies Fact sheet Location <a href=\"https:\/\/www.apex-telescope.org\/ns\/observing\/the-telescope\/\" class=\"read-more\">Read More &#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":39,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ngg_post_thumbnail":0,"spay_email":"","footnotes":""},"class_list":["post-2312","page","type-page","status-publish","hentry"],"featured_image_urls":{"full":"","thumbnail":"","medium":"","medium_large":"","large":"","1536x1536":"","2048x2048":"","education-hub-thumb":""},"post_excerpt_stackable":"<p>Reference paper The Atacama Pathfinder EXperiment (APEX) \u2013 a new submillimeter facility for southern skies. R. G\u00fcsten,&nbsp;L.-\u00c5. Nyman,&nbsp;P. Schilke,&nbsp;K. Menten,&nbsp;C. Cesarsky&nbsp;and&nbsp;R. Booth, Astronomy and Astrophysics, (2006), Volume 454, Number 2, L13-L16. Fact sheetWobbling secondaryTelescope efficiencies Fact sheet LocationLlano de Chajnantor. 50 km east of San Pedro de Atacama, Northern ChileGeodetic Coordinates1Latitude: 23\u00ba 00&#8242; 20&#8243;.8037 SouthLongitude: 67\u00ba 45&#8242; 32&#8243;.9035 WestAltitude: 5104.47 mGeocentric coordinates (ITRF2005)1X : 2225039.5297 mY: -5441197.6292 mZ: -2479303.3597 mMain reflectorDiameter: 12 m264 aluminum panels with an average panel surface r.m.s. of 5 \u03bcm.Full surface accuracy: &lt; 15 \u03bcm r.m.s.Secondary reflectorDiameter: 0.75 m. Hyperboloidal AluminumPolished to an average surface r.m.s.&hellip;<\/p>\n","category_list":"","author_info":{"name":"apex","url":"https:\/\/www.apex-telescope.org\/ns\/author\/apex\/"},"comments_num":"0 comments","featured_image_urls_v2":{"full":"","thumbnail":"","medium":"","medium_large":"","large":"","1536x1536":"","2048x2048":"","education-hub-thumb":""},"post_excerpt_stackable_v2":"<p>Reference paper The Atacama Pathfinder EXperiment (APEX) \u2013 a new submillimeter facility for southern skies. R. G\u00fcsten,&nbsp;L.-\u00c5. Nyman,&nbsp;P. Schilke,&nbsp;K. Menten,&nbsp;C. Cesarsky&nbsp;and&nbsp;R. Booth, Astronomy and Astrophysics, (2006), Volume 454, Number 2, L13-L16. Fact sheetWobbling secondaryTelescope efficiencies Fact sheet LocationLlano de Chajnantor. 50 km east of San Pedro de Atacama, Northern ChileGeodetic Coordinates1Latitude: 23\u00ba 00&#8242; 20&#8243;.8037 SouthLongitude: 67\u00ba 45&#8242; 32&#8243;.9035 WestAltitude: 5104.47 mGeocentric coordinates (ITRF2005)1X : 2225039.5297 mY: -5441197.6292 mZ: -2479303.3597 mMain reflectorDiameter: 12 m264 aluminum panels with an average panel surface r.m.s. of 5 \u03bcm.Full surface accuracy: &lt; 15 \u03bcm r.m.s.Secondary reflectorDiameter: 0.75 m. Hyperboloidal AluminumPolished to an average surface r.m.s.&hellip;<\/p>\n","category_list_v2":"","author_info_v2":{"name":"apex","url":"https:\/\/www.apex-telescope.org\/ns\/author\/apex\/"},"comments_num_v2":"0 comments","_links":{"self":[{"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/2312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/comments?post=2312"}],"version-history":[{"count":46,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/2312\/revisions"}],"predecessor-version":[{"id":5144,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/2312\/revisions\/5144"}],"up":[{"embeddable":true,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/39"}],"wp:attachment":[{"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/media?parent=2312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}