Comet ISON (C/2012 - S1)

[Christian Buil]

A first spectrum of comet ISON. The object is faint for the moment.
The spectral signature is dominated by dust (only very faint gaz emission) :



Alpy 600 on Celestron 11 + f/6.7 focal reducer

Christian B

[Paolo Berardi]

Great observation Christian! I did not think it was already observable with spectrograph. As usual you've pushed forward the limit!

I see several photos of the comet showing a conspicuous green coma (see spaceweather.com), so I expected more visible Swan band on the spectrum. Could be due to not high spectrum SNR or the color of images are a little "pumped"?

Thanks for sharing!

Ciao
Paolo

[Christian Buil]

I have not a definitive response.
My spectrum rather shows the central region, probably richer in dust. The gazeous coma is very faint and difficult to see because
the SNR is not very high (the object is still quite faint!). I can detect fluorescence in the spectrum, so it is there. However,
the dust part now clearly dominate in the nucleus region, photos also shows this. Aind I suspect a (artificial) boost of green component
in some photography...

Christian

[Paolo Berardi]

Thank you Christian, we'll see spectrum evolution when the comet will be brighter.

Ciao
Paolo

[Christian Buil]

For comparison a spectrum, of Encke comet taken with the
same setup.

No apparent nucleus and a large fluorescent coma:



(not easy to detect in imagerie mode from my suburban observatory,
more simple with a spectrograph).

Christian

[Paolo Berardi]

Excellent spectrum! I think this match very well with an RGB image like this:

http://www.astrostudio.at/3_Faint%20Com ... _02_10.jpg

Paolo

[Christian Buil]

La brillance de ISON monte lentement (pas très pressée la bestiole ). Une observation
du spectre cette nuit (24.16 octobre) avec un Alpy 600 et un C11 - pose de 1 heure.
On commence à voir quelques détails dans le spectre, le CN est bien évident à présent)

A spectrum of ISON taken the Oct. 24.162 with Alpy 600 and Celestron 11 (6 x 600 s exposure)



See also the page:

http://www.astrosurf.com/buil/comet/ison/obs.htm

Same night a short exposure spectrum of C/2013 X1 (LINEAR) presently in outburst:



See: http://www.astrosurf.com/buil/comet/C2012_X1/obs.htm

Christian B

[Paolo Berardi]

NASA CIOC explains why comet ISON look green on the basis of Christian spectrum:

http://www.isoncampaign.org/why-does-ison-look-green

Great job!

Paolo

[Christian Buil]

C/ISON spectrum show now more and more details (NH2 lines, ...).
A spectrum taken the October 31.146 UT with Alpy 600 spectrograph:

http://www.astrosurf.com/buil/comet/iso ... 131031.png



See also: http://www.astrosurf.com/buil/comet/ison/obs.htm

My observatory is suburban, not ideal... Many observers are more well
placed and use more largest telescope. I am the only observer
of this major object?????

LISA, Alpy, ... spectrograph class are ideal here, but now you
you can also try with Lhires 600, 1200, .... I encourage observations
(actual weather condition in France are dramatics, but other in the world!?)

============

[Français]
Un nouveau spectre de ISON le 31.146 octobre. Il commence
à montrer pas mal de détails. La météo est tout à fait catastrophique en
France actuellement, mais si vous avez la moindre occasion, ne pas hésiter
de faire cet objet majeur, il devient facile. LISA, Alpy, ... voire des
spectrographes plus résolvants sont possibles.

Christian

[Hubert Boussier]

"I am the only observer of this major object????? "

Non Christian t’es pas tout seul

François Kugel a posté ce spectre de Joan Guarro sur le forum yahoo des observateurs de comètes.
Ici : http://fr.groups.yahoo.com/group/les_co ... ssage/5855
A+