{"id":2212,"date":"2024-07-01T07:39:17","date_gmt":"2024-07-01T06:39:17","guid":{"rendered":"https:\/\/pepsi.aip.de\/?p=2212"},"modified":"2024-09-02T07:45:06","modified_gmt":"2024-09-02T06:45:06","slug":"solar-disk-integration-polarimeter-an-automateddisk-integration-full-stokes-vector-solar-feed-for-thepepsi-spectrograph","status":"publish","type":"post","link":"https:\/\/pepsi.aip.de\/?p=2212","title":{"rendered":"Solar disk integration polarimeter: An automateddisk-integration full-Stokes-vector solar feed for thePEPSI spectrograph"},"content":{"rendered":"\n\n\n<p>We introduce a new solar feed for the PEPSI nighttime spectrograph of the LBT. It enables spectroscopy of the Sun-as-a-star in circular polarization (CP) and linear polarization (LP) with a spectral resolution of 250,000 (\u22480.025 \u00c5 or 600 m s<sup>\u22121<\/sup>) for the wavelength range 383\u2013907 nm. The polarimeter is a dual-beam design with a modified Wollaston prism as beam splitter and linear polarizer combined with a retractable super-achromatic \ud835\udf06\u22154 retarder. The Wollaston beam diameter is 14 mm and large enough that it does not require a classical telescopic feed anymore. Both polarimetric beams are re-imaged into respective integration spheres from which two fibers feed the scrambled light to the spectrograph. The system is fully automated in the sense that it finds the Sun in the morning, closes the guider loop, observes a predefined number of individual spectra, and moves to a home position at the end of the day. Among the scientific aims is Zeeman\u2013Doppler imaging of the Sun as a star over the next activity cycle. Our first-light application detects a clear Stokes-V\/I profile with a full amplitude of 1 \u00d7 10<sup>-4<\/sup> on, for example, October 13, 2023, suggesting a solar disk-averaged line-of-sight net magnetic field of +0.37\u00b10.02 G. Comparison of this value with a contemporary full-disk line-of-sight magnetogram suggests an unsigned mean field of about \u224813 G.<\/p>\n\n\n\n<figure id=\"attachment_2211\" aria-describedby=\"caption-attachment-2211\" style=\"width: 1548px\" class=\"wp-caption alignnone\"><a href=\"https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-2211\" src=\"https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6.jpeg\" alt=\"\" width=\"1548\" height=\"918\" srcset=\"https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6.jpeg 1548w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6-300x178.jpeg 300w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6-1024x607.jpeg 1024w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6-768x455.jpeg 768w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2024\/09\/SDI_pic6-1536x911.jpeg 1536w\" sizes=\"auto, (max-width: 1548px) 100vw, 1548px\" \/><\/a><figcaption id=\"caption-attachment-2211\" class=\"wp-caption-text\">Full facility close up. (a) CAD sketch. Shown are the polarimeter unit, its PlaneWave alt-az mount, the pier, and the Baader AllSky dome. The light-entrance baffle sticks out of the main polarimeter box and points in the south direction. (b) As built. In this picture the telescope points in the east direction shortly after sunrise. Notice the small circular opening in the box to the top right of the baffle, which is the guider telescope.<\/figcaption><\/figure>\n\n\n\n<p>Read more: <a href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2024AN....34540033S\/abstract\">Strassmeier et al. 2024, AN, 345, e240033 <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>We introduce a new solar feed for the PEPSI nighttime spectrograph of the LBT. It enables spectroscopy of the Sun-as-a-star in circular polarization (CP) and linear polarization (LP) with a spectral resolution of 250,000 (\u22480.025 \u00c5 or 600 m s\u22121) for the wavelength range 383\u2013907 nm. The polarimeter is a dual-beam design with a modified &hellip; <a href=\"https:\/\/pepsi.aip.de\/?p=2212\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Solar disk integration polarimeter: An automateddisk-integration full-Stokes-vector solar feed for thePEPSI spectrograph<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-2212","post","type-post","status-publish","format-standard","hentry","category-publications"],"_links":{"self":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/2212","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2212"}],"version-history":[{"count":3,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/2212\/revisions"}],"predecessor-version":[{"id":2215,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/2212\/revisions\/2215"}],"wp:attachment":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2212"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2212"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2212"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}