spectro-aras.com

A supernova has been reported in NGC3254
https://wis-tns.weizmann.ac.il/object/2019np
It is currently faint at mag 18 (right at my limit) but according to the published spectrum it is a type Ia, possibly caught a remarkable 2 weeks before maximum so based on the distance to NGC3254 and that from the spectrum there does not seem to be much redenning, it could reach ~mag 13.

One to watch!

Robin

Hi Robin,

Interesting, Well situated for me right now at a good time of the night too. Midnight

Rainer

Hello,

Last night's result (300/1200 Newton, Alpy 600, 18 micron slit, ATIK 414 EXm, 8 x 1800 sec, 2019.01.18,917, R~670), using Gelato's comparison graph (gelato.tng.iac.es): The moon was high and had to subtract lots of background (30 min exposures at -20C), but the features matching very well.
There is only some shift in the H-alpha absorption .
This SN is reported now at 13.7 mag (http://www.rochesterastronomy.org/snimages/), but since no obvious emission, had to produce good SNR at continuum level.
The weather was good, but I was rather unsure when the clouds will come. Nevertheless, taken ref.stars 3 times (HD89744) as IR and response, so the response calibration quality should be good.
Gelato says 100% SN Ia match, and enlists outstanding confidence with SN2003du (phase: -9.9d).
I believe that my extra UV end here is real (except the last 1-2 pixels cutoff).

Happy hunting!
Peter

PS: attaching the zip

Now at mag 13. An ALPY 600 spectrum from last night and match to a Ia at maximum from GELATO
Robin

Last night's result, 13.7 mag, 3 x 1800 sec: The are many match possibilities (seems the SN IA is more common), but the phase=14.9d is realistic.
The object was low a bit, with some fog present.
Peter

Hi all, the first spectrum of the year. I know... it's terrible!

Same night Peter!

SN 2019np started to decline but it's still relatively bright.



Fluxed with simultaneous photometry (Baader V filter, SHV-H9 CCD and AAVSO sequence) -> V mag = 13.82.

The line identification is based on the paper here.

SNID (Blondin and Tonry 2007, Ap.J. 666, 1024) returns the best match with Ia SN 1998bu at 11.4 days.



Fraction of template by SN type (as a function of quality parameter rlap):



The first template group found by SNID:



Gelato (Harutyunyan et al. 2008, A&A 488, 383) found the same reference (SN 1998bu) but at 13.5 days.



Just to experiment with, this is a single 960s spectrum with the SN in the large slit part (300 micron), the upper profile (offset) is filtered (converting resolution into SNR).



Paolo

Bravo pour vos spectres !

A spectrum taken the 12.9/02/2019 (UVEX + color CMOS ASI294MC + RC10) :



Christian

Spectrum taken the 16.02/02/2019 (the magnitude is uncertain) - bad weather conditions :



Christian B

Ma contribution sur cette belle supernova :


Photo souvenir :


La galaxie hôte NGC3254 (jour nuageux..)


NGC3254 :
NaI = 5922A ; repos = 5893A ; z = 0.004921
MgI = 5190A ; repos = 5174A ; z = 0.0031
Z moyen = 0.0040105

Vr = (z x c) - V hel - V gal
Vr = (0.0040105 x 299792.458) + 17.5
Vr = 1220 kkm/s
V gal = 1180 km/s

D = 17.43 Mpc soit 57 millions d'années-lumière.

Sur le spectre de la supernova le 3/02/19 la raie SiII arrive à 6147.5A ; repose 6355A ; delta = -207.5A
décalage = -0.0326514

d'ou une vitesse de l'éjecta le 3/02/19 :
V ejc = (décalage x c) - Vr NGC3254
V ejc = (-0.0326514 x 299792.458) - 1180
V ejc = -10 969 km/s

La distance donnée par la spectroscopie est de 17.43 Mpc.
Sur la photo NGC3254 fait ~4.815' ce qui donne 0.08025° et donc 0.0014 radian
La taille de NGC3254 fait donc 0.0014 x 17.43 = 0.0024402 Mpc, soit 80 000 AL.