Autour d'Alnitak (bis) (Doublegui)

Celestial hemisphere: Southern · Constellation: Orion (Ori) · Contains: Horsehead nebula · IC 431 · IC 432 · IC 434 · IC 435 · NGC 2023 · NGC 2024 · The star Alnitak (ζOri) · The star σOri

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Autour d'Alnitak (bis)

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Autour d'Alnitak (bis)

Une nuit plus tard, je suis retourné pointer le téléobjectif Tamron à 600 mm sur les nébuleuses de la Flamme et de la Tête de cheval. Cette fois-ci, pas de voiles nuageux et une exposition totale plus longue (2,5 heures : c'est ma plus longue exposition totale), avec l'objectif ouvert au maxi (f/6.3) sur un Canon 6D non défiltré à 3200 ISO.

J'ai du supprimer encore une trentaine de poses unitaires (30 s) qui résultaient d'un filé d'étoiles un peu trop visible je trouve : cela est lié aux limites de ma monture AVX sans autoguidage (et alignée au mieux au pôle selon la méthode 'All stars Polar align') pour cette focale. L'idéal ici serait de pouvoir poser au moins 1 minute à chaque cliché pour maximiser le signal brut de chaque image unitaire. Pour cela, il me faut améliorer la monture ou pratiquer un autoguidage. J'y pense...

Image empilée traitée avec StarTools, pour révéler un maximum de signal par rapport au bruit. J'ai utilisé ici la fonction préalable BIN à 71% sur l'image de base avant de poursuivre le traitement (on gagne un peu en rapport signal/bruit tout en conservant une image de taille encore très respectable).

Par rapport à l'image d'hier, je m'aperçois du gain en signal subtil mais pas énorme non plus, qui permet toutefois de pousser un peu plus le traitement avant l'apparition critique du bruit. Aussi, j'ai réussi ici à mieux limiter la diffusion lumineuse de l'étoile Alnitak autour d'elle : je trouve ainsi que l'on voit mieux la nébuleuse de la Flamme.

J'aime vraiment bien ces nébuleuses autour d'Alnitak, pleines de couleurs, de contrastes... et de mystères !

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Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
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Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

Status	Basic success
Started	...
Astrometry.net job	2543549
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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Autour d'Alnitak (bis)

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