Comete C2019Y4 ATLAS UVEX g1200

Comete C2019Y4 ATLAS UVEX g1200

Postby Dubreuil Pierre » Mon Apr 06, 2020 8:45 am

Bonjour à tous

Après une premiere tentative le 4/04 j'ai tenté de nouveau la comète avec aide et remarques de Christian Buil.
Poses de 1200s au lieu de 600s.

Le panneau d'acquisition cette nuit:

comete1200s.PNG
acquisitions cette nuit


J'ai aussi repris mon soft de guidage sur fente qui m'a enfin permis de guider 2h sans voir la comète sortir de la fente !
Quelques détails dans la raie 4880 CN mais je n'ai pas les compétences pour l'identification.

La comparaison de deux nuits:

compare_cometeUVEX.png
Comete sur 2 nuits



Zoom région Cn 4880:

compare_cometeZOOM.png
ZOOM zone CN 4880A
compare_cometeZOOM.png (135.93 KiB) Viewed 2161 times



Image 300s avec Lunette chercheur (pour le fun !):

imageBrute300sLunetteChercheur.png
Chercheur
imageBrute300sLunetteChercheur.png (403.9 KiB) Viewed 2161 times



Sacrée comète, très faible pour ma config... !

Pierre
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby Jean-Pierre Masviel » Mon Apr 06, 2020 11:39 am

Pierre, pour t'aider à indentifier les raies, tu as la page de M. Brown:

http://web.gps.caltech.edu/~mbrown/comet/

Using high-resolution spectra obtained with the Hamilton echelle spectrograph at Lick Observatory, we have constructed a catalogue of emission lines observed in comets Swift-Tuttle and Brorsen-Metcalf. The spectra cover the range between 3800 and 9900 A with a spectral resolution of ~ 42000. In the spectra, we catalogue 2997 emission lines of which we identify 2437. We find cometary lines due to H, O, C2, CN, NH2, C3, H2O+, CH, and CH+. We list 559 unidentified lines compiled from the two spectra.


Jean-Pierre
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby Michel Verlinden » Tue Apr 07, 2020 9:27 am

Bravo Pierre, vraiment pas facile cette cible, elle n'est pas très brillante.

Une modification de la structure de l'objet est rapportée dans les ATEL. Possible amorce de désintégration amorcée depuis quelques jours.
http://www.astronomerstelegram.org/?read=13622

Image de la comète dans la nuit du 4 au 5 avril. Filtre clair. Addition des images alignées sur les étoiles.
2 queues ? 2 noyaux ? Artéfact ?

c2019y4_add_sk.jpg


Amicalement,
Michel Verlinden
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby Dubreuil Pierre » Tue Apr 07, 2020 1:56 pm

Merci Jean-Pierre pour l'identification. En fait la raie 3880 est large mais que tu CN !

Merci Michel, aussi je vérifierai ce soir si je vois aussi un dédoublement, donc 2 comètes !

Pierre
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby Robin Leadbeater » Tue Apr 07, 2020 2:47 pm

Michel Verlinden wrote:Bravo Pierre, vraiment pas facile cette cible, elle n'est pas très brillante.

Une modification de la structure de l'objet est rapportée dans les ATEL. Possible amorce de désintégration amorcée depuis quelques jours.
http://www.astronomerstelegram.org/?read=13622

Image de la comète dans la nuit du 4 au 5 avril. Filtre clair. Addition des images alignées sur les étoiles.
2 queues ? 2 noyaux ? Artéfact ?



Nick James, (BAA comet section director) has just posted some measurements showing a small change in orbit suggesting either a break up or significant increase in outflowing material. He is also seeing a more diffuse coma
https://britastro.org/node/21355
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby David Boyd » Wed Apr 08, 2020 1:24 pm

Here is a comparison of two spectra of C/2019 Y4 (ATLAS) taken with a LISA on a C11. These are integrations of 130 and 90 mins respectively. The spectrum on 26 March was taken just before the recent disruption of the comet noted by several observers, the spectrum on 6 April was taken after. Reports indicate that the event has reduced the brightness of the comet by about a magnitude and it has become more diffuse. This was apparent from the increased difficulty in guiding on the comet in the later spectrum. The later spectrum also suffers from greater noise beyond that expected just from the reduced exposure time. However, it appears that the event has not introduced any significant change in the spectral profile of the comet.

David

C2019 Y4 (ATLAS) 26 March + April 6 2020.png
C2019 Y4 (ATLAS) 26 March + April 6 2020.png (84.2 KiB) Viewed 2049 times
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Re: Comete C2019Y4 ATLAS UVEX g1200

Postby Dubreuil Pierre » Fri Apr 10, 2020 8:30 am

David Boyd wrote:Here is a comparison of two spectra of C/2019 Y4 (ATLAS) taken with a LISA on a C11. These are integrations of 130 and 90 mins respectively. The spectrum on 26 March was taken just before the recent disruption of the comet noted by several observers, the spectrum on 6 April was taken after. Reports indicate that the event has reduced the brightness of the comet by about a magnitude and it has become more diffuse. This was apparent from the increased difficulty in guiding on the comet in the later spectrum. The later spectrum also suffers from greater noise beyond that expected just from the reduced exposure time. However, it appears that the event has not introduced any significant change in the spectral profile of the comet.

David

The attachment C2019 Y4 (ATLAS) 26 March + April 6 2020.png is no longer available



Belle comparaison David

Je confirme que la chute de luminosité est flagrante et il est pratiquement impossible de guider sur le noyau, ce que j'ai essayé de faire à la limite du décrochage, et pas toujours parfaitement ( passage étoiles proches du noyau).

Ci-dessous le champs du capteur de guidage posé 20s gain maxi caméra ZWO290MM. (poses 6s pendant guidage noyau)

comete-guidage_20200409.png
champs Guidage 20s



La comète (très bruitée, posée 6x1200s)

Comete_3732 to 4381.png
comete 6x1200s
Comete_3732 to 4381.png (141.48 KiB) Viewed 2003 times

Comete_Zoom.png
zoom 3880 A
Comete_Zoom.png (101.49 KiB) Viewed 2003 times


Pierre
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