{"id":10793,"date":"2025-04-02T20:45:20","date_gmt":"2025-04-02T20:45:20","guid":{"rendered":"https:\/\/groupeastronomiespa.be\/astrogas\/ngc2403-en-lhargb\/"},"modified":"2025-06-07T23:01:14","modified_gmt":"2025-06-07T21:01:14","slug":"ngc2403-en-lhargb","status":"publish","type":"post","link":"https:\/\/groupeastronomiespa.be\/astrogas\/ngc2403-en-lhargb\/","title":{"rendered":"NGC2403 en LHaRGB"},"content":{"rendered":"

NGC 2403 (Caldwell 7) est une galaxie spirale situ\u00e9e dans la constellation de la Girafe.
\nSa brillance de surface est assez faible.
\nElle comprend des r\u00e9gions d’hydrog\u00e8ne ionis\u00e9. <\/p>\n

D\u00e9couverte par William Herschel en 1788, elle se situerait \u00e0 11 millions d’ann\u00e9es-lumi\u00e8re de nous.
\nElle est souvent compar\u00e9e \u00e0 M33, la galaxie du Triangle.<\/p>\n

La voici avec le VC200L et son r\u00e9ducteur de focale (taille r\u00e9duite \u00e0 50%, qualit\u00e9 JPEG 75):<\/p>\n

\"\"<\/a><\/p>\n

Le champ fait 44 par 30 minutes d’arc environ.<\/p>\n

Si vous voulez voir l’image en pleine r\u00e9solution et sans perte de qualit\u00e9 : ici<\/a><\/p>\n

Les d\u00e9tails techniques : <\/p>\n

Vixen VC200L, diam\u00e8tre 200 mm, focale 1280 mm (F\/6.4)
\nCam\u00e9ra ASI1600MMPro (3.8 microns)
\nR\u00e9solution 0.61 arcsec\/pixel
\nFiltres Astronomik 12 nm Ha, Optolong (LRGB) et IDAS (LPS2)
\nHa : 19 images de 8 minutes (pour mettre en \u00e9vidence les r\u00e9gions hydrog\u00e8ne, en rouge)
\nL : 311 images de 1 minute
\nR : 109 images de 2 minutes
\nG : 127 …
\nB : 143 …
\nLPS2 : 50 …
\nMonture AP Mach1 guid\u00e9e<\/p>\n

Capture avec MaxIm\/DL, 11 nuits en mars-avril 2025, traitement dans PixInsight.<\/p>\n

Pas mal de petites galaxies sont facilement discernables \u00e0 l’arri\u00e8re-plan.
\nL’image annot\u00e9e par PixInsight en montre quelques unes seulement.<\/p>\n

\"\"<\/a><\/p>\n

Une difficult\u00e9 particuli\u00e8re est la correction des gradients, \u00e0 traiter avec prudence.
\nEn effet, la galaxie pr\u00e9sente de nombreuses extensions, qui donnent l’impression fausse de pr\u00e9sence de gradients.
\nElles n\u00e9cessitent un temps global de pose bien plus \u00e9lev\u00e9 pour \u00eatre bien mises en \u00e9vidence (100 heures ?).
\nJ’en suis encore loin, m\u00eame ici avec 22 heures de pose.
\nVoir \u00e0 ce sujet https:\/\/app.astrobin.com\/i\/2ve5vn<\/a><\/p>\n

Pierre<\/p>\n\n\n

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NGC 2403 (Caldwell 7) est une galaxie spirale situ\u00e9e dans la constellation de la Girafe. Sa brillance de surface est assez faible. Elle comprend des r\u00e9gions d’hydrog\u00e8ne ionis\u00e9. D\u00e9couverte par William Herschel en 1788, elle se situerait \u00e0 11 millions d’ann\u00e9es-lumi\u00e8re de nous. Elle est souvent compar\u00e9e \u00e0 M33, la galaxie du Triangle. La voici […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[2],"tags":[],"class_list":["post-10793","post","type-post","status-publish","format-standard","hentry","category-astrophotos"],"_links":{"self":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/10793","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/comments?post=10793"}],"version-history":[{"count":1,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/10793\/revisions"}],"predecessor-version":[{"id":10856,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/10793\/revisions\/10856"}],"wp:attachment":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/media?parent=10793"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/categories?post=10793"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/tags?post=10793"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}