Supernovae SN2012ec and SN2012et

[Christian Buil]

Supernovae observation with LISA + C9.25 telescope and the new ATIK460EX CCD camera.

First, an image of SN2012ec taken with my the LISA spectrograph guiding camera system (Atik314L):



and now the 2D image (6x 600 sec exposure) - show host galaxy + SN:



(note presence of intense emission line - Halha, NII, SII...)

The spectrum of SN2012ec (15.1/09/2012 - R = 13.8 - Type Ia):



And now my faintest SN for the moment, SN2012et at R = 16.5 (!)



2D spectrum (a faint host galaxy Halpha emission is visible shifted at z = 0.0225):





See also my 2012 supernovae page; http://www.astrosurf.com/buil/supernovae/2012/index.htm

The angular resolution of the telescope can not permit clear separation of
galaxy and supernova spectrum. Remenber, the telescope is only a Celestron 9 (+ surburban condition)....

But the well efficiency for spectro of Atik460EX camera (and the excellent quantum efficiency Sony ICX694 CCD)
is demonstrated (see also http://www.astrosurf.com/buil/isis/noise/result.htm). The detector
is used in binning 2x2 (thanks to small native pixels i.e. 4.54 microns).

------------------------------------------------------------

J'ai utilisé une configuration du LISA avec une caméra Atik460EX exploitée en binning 2x2 et une fente
de 35 microns pour une efficacité maximale en terme de détectivité, mais en sacrifiant un peu la
résolution spectrale (entre R=750 et R=800). Il faut ce rappeler que LISA est aussi un reducteur de focale
de grandissement interne x0.632.

L'image d'une fente de 35 microns sur le détecteur fait donc 22 microns de large. Avec des pixels de
9.08 microns (2x 4.54 = 9.08), l'échantillonnage de la fente (FWHM) est de 2,44 pixels, ce qui est
optimal. Notez qu'une fente de 23 microns donnerait une image trop fine et ne serait pas correctement
échantillonnée (moins de 2 pixels à mi-hauteur).

Cette configuration avec Atik460EX - binning 2x2 - 35 microns est probablement la plus performante
actuellement en terme de détectivité sur LISA. Si on cherche la résolution spectrale ultime
avec LISA, le choix Atik314L + binning 1x1 - fente 23 microns est surement le meilleur
en revanche (difficile de tout avoir d'un coup )

Christian B

[Robin Leadbeater]

Hello Christian,

I was surprised to see H alpha in sn2012ec if it is 1a. Rochester Astronomy lists it as IIp though which is more likely given the H alpha emission

EDIT:

I see it is correct on your webpage.

Cheers
Robin

[Robin Leadbeater]

Hi Christian

I put the spectra through GELATO
https://gelato.tng.iac.es/login.cgi
to see if it could identify them correctly.

It got sn2012ec correct as a type II eg
https://gelato.tng.iac.es/plots/plot_zCmof4Xi4x26.png

but failed with sn2012et even after I tried removing the H alpha line (from the parent galaxy) and filtering to reduce the noise

Cheers
Robin

[Robin Leadbeater]

It got sn2012ec correct as a type II eg
https://gelato.tng.iac.es/plots/plot_zCmof4Xi4x26.png

Oops sorry. that link is to a failed attempt at identifying sn2012et
here is the correct link for sn2012ec
https://gelato.tng.iac.es/plots/plot_F1a2ktCfDNbS.png

Robin

[Christian Buil]

Hi Robin

The Halpha emission in SN2012ec is from the galaxie NGC1084 HII region.
See the 2D spectrum. We can also detect trace of radial velocity variation
along the line induced by galaxy rotation.

With my spatial resolution I can't separate galaxy and SN nova.

All your url seem fail Robin.

Christian

[Robin Leadbeater]

Hi Christian,

The GELATO links work for me but only if I accept the invalid certificate for their secure site. Attached are their identifications both sn.

The contamination in sn2012ec does not look too bad to me. The spectrum of the galaxy core is well separated from the sn. The H alpha emission is expected as it it type II

I agree the contamination is bad for sn2012et. There should be no H alpha as it is type 1a . GELATO failed to identify this one even after removing the h alpha.

Cheers
Robin