Probable SN in NGC 6946

Information about outbursts of eruptive stars, Be activity, ...
Forrest Sims
Posts: 86
Joined: Thu Feb 09, 2017 5:52 pm

Re: Probable SN in NGC 6946

Post by Forrest Sims »

Hello,

Here is my spectrum data of PSNAT2017eaw from early this morning 20-May.

This was taken with a LISA on a C11EdgeHD with an Atik414ex camera. 7 600sec exposures and ISIS calculated R=752. I had very wild spikes below 4000A which made the remainder of the spectrum appear rather flat and featureless. I was thinking somehow I missed the supernova even though the plate solved image indicated I had the correct star. So by chance, I cropped the data below 4000A which produced a much more viewable Relative intensity scale on the y-axis. Following Robin’s discussion I exported the image out of PlotSpectra with a scale of 700x450 pixels as a png file as a test to see how this displays on the web page.

Cheers!
Woody
psnat2017eaw_20170520_335_Woody Sims small.png
psnat2017eaw_20170520_335_Woody Sims small.png (33.97 KiB) Viewed 8477 times
James Foster
Posts: 439
Joined: Sun Jan 24, 2016 7:14 am

Re: Probable SN in NGC 6946

Post by James Foster »

TO: Robin,

RE:"I presume the Hg lines (and fainter Na D emission and other narrow lines) are from residual light pollution sky lines incompletely removed by the background subtraction ?"
Yes, I re-edited the caption to indicate these. When I'm on the rising side of my mount (looking east) I get these lines. There not as bad on the west, since this mor "affluent" portion of Los Angeles got rid of there old Hg street lights years ago.......

James
James Foster
eShel2-Zwo ASI6200MM Pro
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope
LISA IR/Visual Spectroscope (IR Configured)
Alpy 200/600 with Guide/Calibration modules and Photometric slit
Star Analyzer 200
Robin Leadbeater
Posts: 1926
Joined: Mon Sep 26, 2011 4:41 pm
Contact:

Re: Probable SN in NGC 6946

Post by Robin Leadbeater »

Hi James,

Yes my light pollution spectrum has been changing too (and not for the good) over the years too even in my relatively rural area. Predominantly LP sodium originally, then HP sodium, now metal Halide and a lately a few LED (good cut off but some of them high in blue unfortunately) and each brighter than the last. Background subtraction is normally very effective at removing them though.

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
etienne bertrand
Posts: 1040
Joined: Mon Aug 31, 2015 11:26 am

Re: Probable SN in NGC 6946

Post by etienne bertrand »

Spectra of the SN this night high in the sky (~50°)
Image
Paolo Berardi
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: Probable SN in NGC 6946

Post by Paolo Berardi »

Hi all, congratulation for your very nice spectra. From AAVSO light curve it seems that the decline has begun. Maximum brightness happened between 18 and 20 may. Maybe the SN will lose a magnitude, then enter in the plateau stage. Shame it's not a bit brighter to better follow its spectroscopic evolution.

Paolo
Christian Buil
Posts: 1431
Joined: Mon Sep 26, 2011 6:59 pm
Contact:

Re: Probable SN in NGC 6946

Post by Christian Buil »

SN2017eaw the 20.97/05/2017 (C11 + Lhires III 150 g/mm). 7 x 600 sec. exposure and some cirrus cloud:

Image

Christian Buil
Jacques Montier
Posts: 242
Joined: Sun May 13, 2012 2:46 pm

Re: Probable SN in NGC 6946

Post by Jacques Montier »

Hello,

Here is my contribution to SN 2017eaw in NGC 6946 the 2017/05/25.065
8x600s with Atik460EX and Meade ACF 355mm f/d 7
sn2017eaw_v2.png
sn2017eaw_v2.png (47.06 KiB) Viewed 8356 times

Best regards,
--
Jacques Montier
Societe d'Astronomie de Rennes
IAU code J23
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: Probable SN in NGC 6946

Post by Peter Somogyi »

Finally, got my very 1st SN last night:
SN2017eaw_20170528_957_PSO.png
SN2017eaw_20170528_957_PSO.png (30.03 KiB) Viewed 8328 times
It's worth the long exposures, absorptions getting clearly defined!
- Peter
EDIT: normalized spectrum to fit with others view
Paolo Berardi
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: Probable SN in NGC 6946

Post by Paolo Berardi »

Excellent spectrum Peter! Also those of other observers but yours has an incredible SNR.

Spectral features are emphasised now. I also observed it on may 27. I wanted to see the efficiency degradation by placing the target in the narrow and large slit part. The profiles are not IR corrected (single 960 s frames). I think this result is highly dependent on the atmospheric tubulence (counts reduced by half).

Image

The final profile calibrated in absolute flux thanks to the simultaeous V photometry (narrow slit):

Image

Gelato removed uncertainties now:

Image

The SNID analysis shows a good fit with type IIP sn1999em, 1 day after maximum (forced agemin=0):

Image

Paolo
etienne bertrand
Posts: 1040
Joined: Mon Aug 31, 2015 11:26 am

Re: Probable SN in NGC 6946

Post by etienne bertrand »

Exellent spectra Paolo, Peter, Jacques.

Peter your spectr is extraordinair ! The signal is very perfect ! well done !
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