Probable SN in NGC 6946

[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 (33.97 KiB) Viewed 9729 times

[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

[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

[etienne bertrand]

Spectra of the SN this night high in the sky (~50°)

[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]

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



Christian Buil

[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 (47.06 KiB) Viewed 9608 times

Best regards,

[Peter Somogyi]

Finally, got my very 1st SN last night:

SN2017eaw_20170528_957_PSO.png (30.03 KiB) Viewed 9580 times

It's worth the long exposures, absorptions getting clearly defined!
- Peter
EDIT: normalized spectrum to fit with others view

[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).



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



Gelato removed uncertainties now:



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



Paolo

[etienne bertrand]

Exellent spectra Paolo, Peter, Jacques.

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