{"id":1375,"date":"2021-04-30T11:48:53","date_gmt":"2021-04-30T09:48:53","guid":{"rendered":"http:\/\/astrosurf-magazine.com\/?p=1375"},"modified":"2021-06-11T11:46:57","modified_gmt":"2021-06-11T09:46:57","slug":"une-comete-decouverte-a-loculaire","status":"publish","type":"post","link":"https:\/\/astrosurf-magazine.com\/index.php\/2021\/04\/30\/une-comete-decouverte-a-loculaire\/","title":{"rendered":"Une com\u00e8te d\u00e9couverte \u00e0 l\u2019oculaire !"},"content":{"rendered":"\n\n[et_pb_section fb_built=”1″ _builder_version=”4.9.4″ _module_preset=”default”][et_pb_row _builder_version=”4.9.4″ _module_preset=”default”][et_pb_column _builder_version=”4.9.4″ _module_preset=”default” type=”4_4″][et_pb_text _builder_version=”4.9.4″ _module_preset=”default” hover_enabled=”0″ sticky_enabled=”0″]

Avec les syst\u00e8mes automatiques qui cherchent tout ce qui bouge dans le ciel, c’est un miracle qu’un amateur puisse encore d\u00e9couvrir une com\u00e8te visuellement.<\/em><\/p>[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.9.4″ _module_preset=”default” column_structure=”1_2,1_2″][et_pb_column _builder_version=”4.9.4″ _module_preset=”default” type=”1_2″][et_pb_text _builder_version=”4.9.4″ _module_preset=”default” hover_enabled=”0″ sticky_enabled=”0″]

C\u2019est pourtant ce qui s\u2019est pass\u00e9 le 7 novembre 2018 \u00e0 23 heures TU, lorsque Don Machholz a d\u00e9couvert une nouvelle com\u00e8te dans la Vierge. Et cerise sur le g\u00e2teau il l\u2019a d\u00e9couverte \u00e0 l\u2019oculaire de son t\u00e9lescope situ\u00e9 \u00e0 Colfax, en Californie. Heureusement pour nous, il est situ\u00e9 en dehors de la zone des incendies et de leurs fum\u00e9es qui ravagent cet \u00e9tat et son ciel. Depuis 2010, date de sa onzi\u00e8me d\u00e9couverte, c\u2019est 746 heures d\u2019observation \u00e0 l\u2019oculaire qui lui ont \u00e9t\u00e9 n\u00e9cessaires pour engranger sa d\u00e9sormais douzi\u00e8me com\u00e8te.
Deux observateurs japonais ( Shigehisa Fujikawa et Masayuki Iwamoto) ont ind\u00e9pendamment rep\u00e9r\u00e9 l’objet sur des photographies et ont pu ajouter leurs noms \u00e0 celui de Machholz.
Lors de ma premi\u00e8re observation, l\u2019atmosph\u00e8re n\u2019\u00e9tait pas tr\u00e8s coop\u00e9rante. Le 14 novembre, c\u2019est dans les brumes matinales que j\u2019ai pu l\u2019observer. Arriver \u00e0 en estimer diam\u00e8tre de la chevelure, magnitude apparente ainsi que niveau de condensation avec pr\u00e9cision n\u2019\u00e9tait quasiment pas possible.
Le lendemain la m\u00e9t\u00e9o n\u2019est toujours pas au beau fixe. Pourtant, ce 15 novembre, je mets mon r\u00e9veil \u00e0 4h, sait-on jamais. Rapide d\u00e9placement \u00e0 moins d\u2019un kilom\u00e8tre de chez moi, au m\u00eame endroit que la veille. Et bingo, le ciel est superbe (SQM 21,30), ce qui me permet d’observer la com\u00e8te, d\u2019en estimer les param\u00e8tres et d\u2019en dessiner l\u2019apparence. D\u00e9couverte le 7 \u00e0 la magnitude +10,2 je l\u2019estime aujourd\u2019hui \u00e0 +8,5, une condensation de 5\/10 et un diam\u00e8tre de la coma de 4\u2019.
L\u2019utilisation d\u2019un filtre SWAN permet de faire tr\u00e8s bien ressortir la com\u00e8te sur le fond du ciel, ce n\u2019est pas toujours le cas (voir figure 2).
Lors de cette seconde nuit d\u2019observation j\u2019ai pu admirer \u00e9galement le lever de la conjonction V\u00e9nus-Spica, l\u2019Epi de la Vierge qui a donn\u00e9 un peu plus de peps \u00e0 mon aquarelle (voir figure 1).
Bien que sur les rares photos prises de cette com\u00e8te on distingue une tr\u00e8s longue queue bleut\u00e9e toute fine ainsi qu\u2019une coma vert fluo, en visuel il n\u2019y a pas grand-chose \u00e0 dessiner, mais ce n\u2019est peut-\u00eatre que partie remise ?
En cet automne 2018, j\u2019ai d\u00e9j\u00e0 pu observer les com\u00e8tes p\u00e9riodiques suivantes (voir figure 3) :
\u2022 21P\/Giacobini-Zinner<\/span>, d\u00e9couverte \u00e0 Nice en d\u00e9cembre 1900 qui a une p\u00e9riode de 6 ans,
\u2022 38P\/Stephan-Oterma<\/span> qui a une p\u00e9riode de 38 ans,
\u2022 46P\/Wirtanen<\/span>, \u00e0 son sujet voyez la suite de sa saga dans ce num\u00e9ro d’Astrosurf-Magazine,
\u2022 64P\/Swift-Gehrels<\/span> dont la p\u00e9riode est de 9 ans.
Mais seule la com\u00e8te C\/2018 V1 (Machholz-Fujikawa-Iwamoto) est une nouvelle venue.
Cette d\u00e9couverte est tr\u00e8s int\u00e9ressante. Les com\u00e8tes p\u00e9riodiques sont des astres qui ont d\u00e9j\u00e0 connu le soleil de pr\u00e8s. On les conna\u00eet, on gu\u00e8te leurs retours, mais celle de Machholz passera pr\u00e8s de notre \u00e9toile pour la toute premi\u00e8re fois, sa neige de surface n\u2019a pas encore \u00e9t\u00e9 sublim\u00e9e, elle est ce qu\u2019elle \u00e9tait au tout d\u00e9but de la cr\u00e9ation de notre syst\u00e8me plan\u00e9taire.
Le passage au p\u00e9rih\u00e9lie doit avoir lieu le 3 d\u00e9cembre, en passant au plus pr\u00e8s de la terre le 27 novembre.
Traquer ces objets a toujours \u00e9t\u00e9 une passion dans ma passion, traquer le d\u00e9placement de ces grosses boules de neige capricieuses a r\u00e9ellement quelque chose de magique.<\/p>[\/et_pb_text][\/et_pb_column][et_pb_column _builder_version=”4.9.4″ _module_preset=”default” type=”1_2″][et_pb_image src=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/aqu-c2018v1_hh-scaled.jpg” _builder_version=”4.9.4″ _module_preset=”default” title_text=”Aqu C2018v1 Hh” url=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/aqu-c2018v1_hh-scaled.jpg” hover_enabled=”0″ sticky_enabled=”0″][\/et_pb_image][et_pb_text _builder_version=”4.9.4″ _module_preset=”7e56652b-4cb5-4e2b-88e6-1271b53869a4″ hover_enabled=”0″ sticky_enabled=”0″]

1. Autoportrait de l’auteur en cours d’observation de la com\u00e8te C\/2018 V1 (Machholz-Fujikawa-Iwamoto).<\/em><\/span><\/p>[\/et_pb_text][et_pb_image src=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/20180708-21P_hh-scaled.jpg” _builder_version=”4.9.4″ _module_preset=”default” title_text=”20180708 21P Hh” url=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/20180708-21P_hh-scaled.jpg” hover_enabled=”0″ sticky_enabled=”0″][\/et_pb_image][et_pb_text _builder_version=”4.9.4″ _module_preset=”7e56652b-4cb5-4e2b-88e6-1271b53869a4″ hover_enabled=”0″ sticky_enabled=”0″]

2. C\/2018 V1 (Machholz-Fujikawa-Iwamoto) – 15\/10\/2018 04:20 TU. <\/span>Dessin \u00e0 l’oculaire d’une Vixen Bino 125mm avec filtre Swan et grossissement 40x. F.O.S. (Field Of Sketch) donne le champ du dessin, ici 70 minutes d\u2019arc.<\/span><\/em><\/p>[\/et_pb_text][et_pb_image src=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/automne2018-scaled.jpg” _builder_version=”4.9.4″ _module_preset=”default” title_text=”Automne2018″ url=”https:\/\/astrosurf-magazine.com\/wp-content\/uploads\/2021\/04\/automne2018-scaled.jpg” hover_enabled=”0″ sticky_enabled=”0″][\/et_pb_image][et_pb_text _builder_version=”4.9.4″ _module_preset=”7e56652b-4cb5-4e2b-88e6-1271b53869a4″ hover_enabled=”0″ sticky_enabled=”0″]

3. Autres com\u00e8tes p\u00e9riodiques observ\u00e9es et dessin\u00e9es au cours de l’automne 2018.<\/em><\/span><\/p>[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":1374,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":""},"categories":[22],"tags":[52],"yoast_head":"\nUne com\u00e8te d\u00e9couverte \u00e0 l\u2019oculaire ! - Astrosurf-Magazine<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/astrosurf-magazine.com\/index.php\/2021\/04\/30\/une-comete-decouverte-a-loculaire\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Une com\u00e8te d\u00e9couverte \u00e0 l\u2019oculaire ! 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