{"id":13342,"date":"2025-11-05T11:04:02","date_gmt":"2025-11-05T21:04:02","guid":{"rendered":"https:\/\/www.eaobservatory.org\/jcmt\/?p=13342"},"modified":"2025-11-05T11:04:02","modified_gmt":"2025-11-05T21:04:02","slug":"noise-arcs-in-scuba-2-maps","status":"publish","type":"post","link":"https:\/\/www.eaobservatory.org\/jcmt\/2025\/11\/noise-arcs-in-scuba-2-maps\/","title":{"rendered":"Noise Arcs in SCUBA-2 Maps"},"content":{"rendered":"<p>Some reductions of SCUBA-2 data exhibit arc-like structures, most often in &ldquo;blank field&rdquo; observations taken in good weather and at high elevation.  An example reduction of a group of observations exhibiting this issue can be seen below, along with an alternative reduction where it has been suppressed by altering the dimmconfig parameters.<\/p>\n<table>\n<tr>\n<td><img loading=\"lazy\" src=\"https:\/\/www.eaobservatory.org\/JCMT\/scicom\/scuba2-noise-arcs\/red_4p00_200_256.png\" width=\"256\" height=\"256\" \/><\/td>\n<td><img loading=\"lazy\" src=\"https:\/\/www.eaobservatory.org\/JCMT\/scicom\/scuba2-noise-arcs\/red_4p00_125_256.png\" width=\"256\" height=\"256\" \/><\/td>\n<\/tr>\n<tr>\n<th>Example reduction showing the issue with the standard blank field config.<\/th>\n<th>Reduction of the same data with reduced <tt>filt_edge_largescale <\/tt> parameter<\/th>\n<\/tr>\n<\/table>\n<p>Please see the <a href=\"https:\/\/www.eaobservatory.org\/JCMT\/scicom\/scuba2-noise-arcs\/\">investigation of parameters to suppress noise arcs<\/a> for more detailed information about this issue.  There you can find example reductions made with varying parameters in <a href=\"https:\/\/www.eaobservatory.org\/JCMT\/scicom\/scuba2-noise-arcs\/grid_red.html\">blank field<\/a> and more typical <a href=\"https:\/\/www.eaobservatory.org\/JCMT\/scicom\/scuba2-noise-arcs\/grid_flt.html\">flt-based<\/a> configurations.  But in summary, modifying the blank field config. to reduce the filt_edge_largescale parameter, as in the configuration below, may be sufficient.<\/p>\n<pre>\r\n^$STARLINK_DIR\/share\/smurf\/dimmconfig_blank_field.lis\r\nfilt_edge_largescale = 125\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Some reductions of SCUBA-2 data exhibit arc-like structures, most often in &ldquo;blank field&rdquo; observations taken in good weather and at high elevation. An example reduction of a group of observations exhibiting this issue can be seen below, along with an alternative reduction where it has been suppressed by altering the\u2026 <a class=\"continue-reading-link\" href=\"https:\/\/www.eaobservatory.org\/jcmt\/2025\/11\/noise-arcs-in-scuba-2-maps\/\">Continue reading<\/a><\/p>\n","protected":false},"author":89,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[36],"tags":[46],"_links":{"self":[{"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/posts\/13342"}],"collection":[{"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/users\/89"}],"replies":[{"embeddable":true,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/comments?post=13342"}],"version-history":[{"count":4,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/posts\/13342\/revisions"}],"predecessor-version":[{"id":13346,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/posts\/13342\/revisions\/13346"}],"wp:attachment":[{"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/media?parent=13342"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/categories?post=13342"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.eaobservatory.org\/jcmt\/wp-json\/wp\/v2\/tags?post=13342"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}