{"id":2140,"date":"2020-02-01T14:28:38","date_gmt":"2020-02-01T17:28:38","guid":{"rendered":"http:\/\/scidev\/wordpress\/?page_id=2140"},"modified":"2025-07-10T10:50:58","modified_gmt":"2025-07-10T14:50:58","slug":"sepia660","status":"publish","type":"page","link":"https:\/\/www.apex-telescope.org\/ns\/observing\/the-telescope\/instruments\/sepia660\/","title":{"rendered":"SEPIA660"},"content":{"rendered":"\n<h4 class=\"wp-block-heading\">Technical details<\/h4>\n\n\n\n<p>The SEPIA660 channel is a dual polarisation 2SB receiver delivered by <a href=\"https:\/\/nova-astronomy.nl\/instrumentation\/\" target=\"_blank\" rel=\"noreferrer noopener\">the NOVA group<\/a>. It was installed and commissioned during the second half of 2018. It replaced the previous DSB receiver built to the specifications of ALMA band 9, based on a pre-production ALMA Band 9 receiver cartridge.<\/p>\n\n\n\n<p>The SEPIA660 receiver has two IF outputs per polarisation, USB and LSB, each covering 4-12 GHz, adding up a total of 32 GHz instantaneous IF bandwidth. The central frequencies of the two sidebands are separated by 16 GHz. <\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1150\" height=\"426\" src=\"http:\/\/www.apex-telescope.org\/ns\/wp-content\/uploads\/2020\/07\/TuningSEPIAB9.png\" alt=\"\" class=\"wp-image-3123\"\/><\/figure>\n\n\n\n<p>Each sideband (and polarisation) is recorded by two FFTS spectrometer units, each of them sampling 4 GHz, in the following configuration:<\/p>\n\n\n\n<div class=\"wp-block-ugb-icon-list ugb-icon-list ugb-icon--icon-arrow ugb-1b8b281 ugb-icon-list--v2 ugb-main-block\"><style>.ugb-1b8b281 li{margin-bottom:2px !important}.ugb-1b8b281 li::before{background-image:url('data:image\/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAxOTAgMTkwIiBzdHlsZT0iZmlsbDogIzAwZDA4NCAhaW1wb3J0YW50OyBjb2xvcjogIzAwZDA4NCAhaW1wb3J0YW50Ij48cGF0aCBkPSJNNTkuNCAxNzcuNWw4Mi40LTgyLjQtODIuNC04Mi4zLTEwLjYgMTAuNiA3MS44IDcxLjctNzEuOCA3MS44IDEwLjYgMTAuNnoiIGZpbGw9IiMwMGQwODQiIHN0cm9rZT0iIzAwZDA4NCIgc3R5bGU9ImZpbGw6IHJnYigwLCAyMDgsIDEzMik7IHN0cm9rZTogcmdiKDAsIDIwOCwgMTMyKTsiLz48L3N2Zz4=')}.ugb-1b8b281 li ul{margin-bottom:2px !important}.ugb-1b8b281.ugb-icon-list ul{columns:1}.ugb-1b8b281 .ugb-inner-block{text-align:left}<\/style><div class=\"ugb-inner-block\"><div class=\"ugb-block-content\"><ul><li>FFTS1:  4.17 &#8211; 8.17 GHz IF bandwidth<\/li><li>FFTS2:  8.07 &#8211; 12.07 GHz IF bandwidth<\/li><\/ul><\/div><\/div><\/div>\n\n\n\n<p>Therefore, both units overlap in the middle for about 100 MHz and the full coverage is slightly smaller than 8 GHz (7.9 GHz). <\/p>\n\n\n\n<p>Line setups are designed to avoid placing the astronomical interesting line in the overlap region where aliasing effects are present. This is why the tuning sky frequency is placed in the middle part of one of the FFTS units, at 6 GHz from the LO frequency. In this configuration (shown in the figure above) the spectral coverage is not symmetric around the tuning frequency, and this needs to be considered when aiming for other transitions inside the band or when performing line surveys.<\/p>\n\n\n\n<p>The sideband rejection ratio is by design >10 dB over the full  band coverage.<\/p>\n\n\n\n<p>The commissioning at the telescope of SEPIA660 was successfully done in Aug-Oct 2018. By that time, the instrument was occupying one of the PI positions inside the Nasmyth cabin (A-cabin). The noise temperature was measured to be &lt; 335 K all over the band, with a reference value ~225 K @ 600 GHz. These noise values determined in the commissioning have been incorporated in the SEPIA660 <a href=\"https:\/\/www.apex-telescope.org\/ns\/observing-time-calculators\/\" data-type=\"page\" data-id=\"2942\">observing time estimator<\/a>. The sideband suppression was measured to be better than 20 dB and the stability (Allan times) were estimated to be between 5-10s (total power) and >100 s (spectroscopic) at different tuning frequencies. In January 2019 the cryostat was moved to the middle facility position (also in the A cabin) and some of the commissioning measurements were repeated, confirming similar results.<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h4 class=\"wp-block-heading\">SEPIA660 Atmospheric window<\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1200\" height=\"700\" src=\"http:\/\/www.apex-telescope.org\/ns\/wp-content\/uploads\/2020\/07\/ATM_model_SEPIA660.png\" alt=\"\" class=\"wp-image-3124\"\/><\/figure>\n\n\n\n<p>In the figure above the atmospheric transmission in the SEPIA660 frequency range (600-720 GHz) is shown. At this atmospheric window you need submillimeter weather conditions to have atmospheric transmission higher than 50%. <\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Observing with SEPIA660<\/h3>\n\n\n\n<p>SEPIA660 is a Facility receiver so everybody is welcomed to use it, independently of the <a href=\"http:\/\/www.apex-telescope.org\/ns\/partners\/\">partner<\/a>. Given the 2SB capability and the wide bandwidth coverage (7.9 GHz + 7.9 GHz), SEPIA660 is a very interesting instrument to perform line surveys at high frequency.<\/p>\n\n\n\n<p>If you are interested only in particular transitions, think on a strategy to place the lines of your interest with the minimum number of tunings. Due to the number of atmospheric absorption within this band, it is essential that you check the <a rel=\"noreferrer noopener\" href=\"http:\/\/www.apex-telescope.org\/ns\/instrument-setup-tool\/\" target=\"_blank\">Instrumen<\/a><a href=\"http:\/\/www.apex-telescope.org\/ns\/instrument-setup-tool\/\" target=\"_blank\" rel=\"noreferrer noopener\">t<\/a><a href=\"http:\/\/www.apex-telescope.org\/ns\/instrument-setup-tool\/\"> setup tool<\/a> to optimise your tunings.<\/p>\n\n\n\n<div class=\"wp-block-ugb-icon-list ugb-icon-list ugb-icon--icon-check ugb-f48a51a ugb-icon-list--v2 ugb-main-block\"><style>.ugb-f48a51a li{margin-bottom:8px !important}.ugb-f48a51a li::before{background-image:url('data:image\/svg+xml;base64,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')}.ugb-f48a51a li ul{margin-bottom:8px !important}.ugb-f48a51a.ugb-icon-list ul{columns:1}<\/style><div class=\"ugb-inner-block\"><div class=\"ugb-block-content\"><ul><li>Check the <a href=\"https:\/\/www.apex-telescope.org\/ns\/observing-run\/observing\/spectral-line-catalogs\/#660\" data-type=\"page\">SEPIA660 line catalogue<\/a> to find typical astronomical lines within the band.<\/li><li><a href=\"https:\/\/www.apex-telescope.org\/ns\/observing-run\/observing\/instrument-setup-tool\/\" target=\"_blank\" rel=\"noreferrer noopener\">Instrument setup tool<\/a>. Find the right configuration for your observing setup when planning SEPIA660 observations.<\/li><li><a href=\"https:\/\/www.apex-telescope.org\/ns\/observing-run\/observing\/observing-time-calculators\/\">Observing time estimator for Heterodyne receivers<\/a><\/li><\/ul><\/div><\/div><\/div>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>Technical papers about SEPIA660.<\/p>\n\n\n\n<p><em>Belitsky, V.; Lapkin, I.; Fredrixon, M.; Meledin, D.; Sundin, E.; Billade, B.; Ferm, S. -E.; Pavolotsky, A.; Rashid, H.; Strandberg, M.; Desmaris, V.; Ermakov, A.; Krause, S.; Olberg, M.; Aghdam, P.; Shafiee, S.; Bergman, P.; De Beck, E.; Olofsson, H.; Conway, J. De Breuck, C.; Immer, K.; Yagoubov, P.; Montenegro-Montes, F. M.; Torstensson, K.; P\u00e9rez-Beaupuits, J. -P.; Klein, T.; Boland, W.; Baryshev, A. M.; Hesper, R.; Barkhof, J.; Adema, J.; Bekema, M. E.; Koops, A<\/em>. <a href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2018A%26A...612A..23B\/abstract\">SEPIA &#8211; a new single pixel receiver at the APEX telescope<\/a>&nbsp;Astronomy &amp; Astrophysics, (2018) Volume 612, A23, (12 pages).<\/p>\n\n\n\n<p><em>Baryshev, A. M.; Hesper, R.; Mena, F. P.; Klapwijk, T. M.; van Kempen, T. A.; Hogerheijde, M. R.; Jackson, B. D.; Adema, J.; Gerlofsma, G. J.; Bekema, M. E.; Barkhof, J.; de Haan-Stijkel, L. H. R.; van den Bemt, M.; Koops, A.; Keizer, K.; Pieters, C.; Koops van het Jagt, J.; Schaeffer, H. H. A.; Zijlstra, T.; Kroug, M.Lodewijk, C. F. J.; Wielinga, K.; Boland, W.; de Graauw, M. W. M.; van Dishoeck, E. F.; Jager, H.; Wild, W<\/em>., <a aria-label=\"The ALMA Band 9 receiver. Design, construction, characterization and first light (opens in a new tab)\" href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2015A%26A...577A.129B\/abstract\" target=\"_blank\" rel=\"noreferrer noopener\">The ALMA Band 9 receiver. Design, construction, characteri<\/a><a aria-label=\"The ALMA Band 9 receiver. Design, construction, characterization and first light (opens in a new tab)\" href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2015A%26A...577A.129B\/abstract\" target=\"_blank\" rel=\"noreferrer noopener\">s<\/a><a aria-label=\"The ALMA Band 9 receiver. Design, construction, characterization and first light (opens in a new tab)\" href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2015A%26A...577A.129B\/abstract\" target=\"_blank\" rel=\"noreferrer noopener\">ation and first light<\/a>, Astronomy &amp; Astrophysics, Vol 577, A129 (12 pages).<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>Technical details The SEPIA660 channel is a dual polarisation 2SB receiver delivered by the NOVA group. It was installed and commissioned during the second half of 2018. It replaced the previous DSB receiver built to the specifications of ALMA band <a href=\"https:\/\/www.apex-telescope.org\/ns\/observing\/the-telescope\/instruments\/sepia660\/\" class=\"read-more\">Read More &#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":10,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ngg_post_thumbnail":0,"spay_email":"","footnotes":""},"class_list":["post-2140","page","type-page","status-publish","hentry"],"featured_image_urls":{"full":"","thumbnail":"","medium":"","medium_large":"","large":"","1536x1536":"","2048x2048":"","education-hub-thumb":""},"post_excerpt_stackable":"<p>Technical details The SEPIA660 channel is a dual polarisation 2SB receiver delivered by the NOVA group. It was installed and commissioned during the second half of 2018. It replaced the previous DSB receiver built to the specifications of ALMA band 9, based on a pre-production ALMA Band 9 receiver cartridge. The SEPIA660 receiver has two IF outputs per polarisation, USB and LSB, each covering 4-12 GHz, adding up a total of 32 GHz instantaneous IF bandwidth. The central frequencies of the two sidebands are separated by 16 GHz. Each sideband (and polarisation) is recorded by two FFTS spectrometer units, each&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>Technical details The SEPIA660 channel is a dual polarisation 2SB receiver delivered by the NOVA group. It was installed and commissioned during the second half of 2018. It replaced the previous DSB receiver built to the specifications of ALMA band 9, based on a pre-production ALMA Band 9 receiver cartridge. The SEPIA660 receiver has two IF outputs per polarisation, USB and LSB, each covering 4-12 GHz, adding up a total of 32 GHz instantaneous IF bandwidth. The central frequencies of the two sidebands are separated by 16 GHz. Each sideband (and polarisation) is recorded by two FFTS spectrometer units, each&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\/2140","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=2140"}],"version-history":[{"count":17,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/2140\/revisions"}],"predecessor-version":[{"id":5134,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/2140\/revisions\/5134"}],"up":[{"embeddable":true,"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/pages\/10"}],"wp:attachment":[{"href":"https:\/\/www.apex-telescope.org\/ns\/wp-json\/wp\/v2\/media?parent=2140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}