{"id":8693,"date":"2008-07-05T18:04:39","date_gmt":"2008-07-05T18:04:39","guid":{"rendered":"https:\/\/groupeastronomiespa.be\/astrogas\/retour-sur-m27\/"},"modified":"2025-07-14T11:13:13","modified_gmt":"2025-07-14T09:13:13","slug":"retour-sur-m27","status":"publish","type":"post","link":"https:\/\/groupeastronomiespa.be\/astrogas\/retour-sur-m27\/","title":{"rendered":"Retour sur M27"},"content":{"rendered":"

Voici quelques jours, je proposais une image de M27 – un classique de l’\u00e9t\u00e9 – r\u00e9sultat de la combinaison de 7 images de 10 minutes.
\nPlusieurs d’entre vous m’ont signal\u00e9 que l’image poss\u00e9dait assez de d\u00e9tails qui m\u00e9ritaient d’\u00eatre mis en valeur.
\nComme les captures sont \u00e0 F\/9, j’ai profit\u00e9 aussi de ces derniers jours pour reprendre quelques images afin d’augmenter le signal – en fait le temps total de pose a quasi doubl\u00e9.<\/p>\n

Voici le r\u00e9sultat.<\/p>\n

3 nuits, avec:
\n– 7 poses de 10 minutes – h\u00e9las sans filtre
\n– 4 poses de 10 minutes – avec filtre IDAS LPS
\n– 2 poses de 15 minutes – idem<\/p>\n

Pour chaque nuit: 16 offsets, 16 flats et 1 ou 2 darks, utilis\u00e9s pour cr\u00e9er une bad pixel map<\/p>\n

CCD: Starlight Xpress SXVF-M25C
\nautoguidage via SXV autoguider et off-axis-guider, corrections toutes les 5 \u00e0 10 secondes, guide speed= 0.25 sidereal
\nVC200L \u00e0 F\/9 (1800 mm de focale – 1 pixel = 0.89 arcseconde)
\nMonture AP MAch1 avec PEM<\/p>\n

Capture et processing dans MaxIm, avec alignement puis crop et export en TIFF<\/p>\n

Traitement final dans PhotoShop, pour faire ressortir les d\u00e9tails, avec les \u00e9tapes principales ci-dessous:
\n– curves + levels
\n– \u00e9limination du vignettage r\u00e9siduel (filtre RC-astro, comme conseill\u00e9 par Andr\u00e9 en son temps – merci !)
\n– smooth de la partie ext\u00e9rieure de la n\u00e9buleuse (gaussian blur)
\n– sharpening l\u00e9ger de la partie centrale de la n\u00e9buleuse (unsharp mask) et des \u00e9toiles
\n– sortie en JPEG, qualit\u00e9 50%<\/p>\n

J’esp\u00e8re avoir trouv\u00e9 un compromis entre r\u00e9alit\u00e9 et \u00ab\u00a0photoshoperies\u00a0\u00bb dont je ne suis pas trop friand. Mais \u00e7a valait le coup d’essayer en effet.<\/p>\n

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

Image compl\u00e8te:
\n\"\"<\/a><\/p>\n

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

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\n Veuillez voter<\/span>\n <\/div>\n <\/div>\n","protected":false},"excerpt":{"rendered":"

Voici quelques jours, je proposais une image de M27 – un classique de l’\u00e9t\u00e9 – r\u00e9sultat de la combinaison de 7 images de 10 minutes. Plusieurs d’entre vous m’ont signal\u00e9 que l’image poss\u00e9dait assez de d\u00e9tails qui m\u00e9ritaient d’\u00eatre mis en valeur. Comme les captures sont \u00e0 F\/9, j’ai profit\u00e9 aussi de ces derniers jours […]<\/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-8693","post","type-post","status-publish","format-standard","hentry","category-astrophotos"],"_links":{"self":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/8693","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=8693"}],"version-history":[{"count":3,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/8693\/revisions"}],"predecessor-version":[{"id":16130,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/8693\/revisions\/16130"}],"wp:attachment":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/media?parent=8693"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/categories?post=8693"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/tags?post=8693"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}