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Potentially bright supernova in NGC4636

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#1 robin_astro

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Posted 12 January 2020 - 06:47 PM

While we wait for Betelgeuse to explode, there is another supernova which has the potential to be the brightest for some time

 

https://wis-tns.weiz...l/object/2020ue

Discovered today at mag 15 by Koichi Itagaki and confirmed as a type Ia, this could reach brighter than mag 12 depending on the extinction in the host  galaxy.

Cheers
Robin


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#2 Redbetter

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Posted 12 January 2020 - 08:42 PM

I don't see a spectra/type report although it is listed as Type Ia.  I guess they are making the assumption based on the host being an elliptical galaxy.   Should make a good target for the 60ED. 


Edited by Redbetter, 12 January 2020 - 10:14 PM.


#3 robin_astro

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Posted 12 January 2020 - 09:27 PM

I don't see a specta/type report although it is listed as Type Ia.  I guess they are making the assumption based on the host being an elliptical galaxy.   Should make a good target for the 60ED. 

The classification spectrum is there, it is just not displaying properly because there are some extremely high spurious values at the far end. If you zoom in eventually you can see the spectrum and the Si II absorption lines characteristic of a type Ia at the host redshift - 15000km/s expansion velocity, see attached screen shot.

 

SN0202ue_classification.png


Edited by robin_astro, 12 January 2020 - 09:29 PM.

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#4 Rich (RLTYS)

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Posted 13 January 2020 - 11:02 AM

The Bright Supernova Web site has some info on this new SN 2020ue. Here's the discovery image.

 

Attached Thumbnails

  • 2020ue.jpg

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#5 Rich (RLTYS)

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Posted 15 January 2020 - 05:04 PM

Here's my image of SN 2020ue taken on the morning of the 14th. Using comp star mags from Wikisky (none available from the AAVSO) I estimated 2020ue's brightness at mag 14.9.

Attached Thumbnails

  • SN 2020ue T2hm 1-14-20r.png

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#6 Aquarellia

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Posted 17 January 2020 - 12:40 AM

From Wikipedia a supernova has been observed in NGC 4636 in 1939. It was a type Ia too, and the maximum magnitude was estimated to be 11.9.  Same type, same distance so out of local light absorption, the magnitude of this one of today must reach similar value, isn't it? 

And then 14.9 two days after the discovery I wonder that this means maybe that we are days after the maximum?

Michel


Edited by Aquarellia, 17 January 2020 - 12:47 AM.


#7 robin_astro

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Posted 17 January 2020 - 06:23 AM

From Wikipedia a supernova has been observed in NGC 4636 in 1939. It was a type Ia too, and the maximum magnitude was estimated to be 11.9.  Same type, same distance so out of local light absorption, the magnitude of this one of today must reach similar value, isn't it? 

And then 14.9 two days after the discovery I wonder that this means maybe that we are days after the maximum?

Michel

The spectrum suggests it was discovered before maximum and I have had feedback from a professional team that it is currently brightening. (The problem with magnitude measurements is they might be based on different comparision stars)

 

There are a couple of reasons why it may not be the same brightness as 1939A 

 

1. There may be a different amount of interstellar absorption in the host galaxy between it and us compared with SN 1939A .  (I have not seen any estimates of extinction but from a quick look at the spectrum it does not look exceptionally high.

 

2. Not all Ia have exactly the same luminosity.  (To use them as "standard candles"  the luminosity has to be corrected slightly based on the shape of the light curve)

 

It "should" be a bright one but we will have to  see

 

Cheers

Robin


Edited by robin_astro, 17 January 2020 - 06:25 AM.

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#8 robin_astro

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Posted 17 January 2020 - 06:35 AM

There are also outlier type Ia which have significantly higher and lower luminosity eg

1991bg-like  (under luminous)

1991T-like (over luminous)


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#9 Aquarellia

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Posted 17 January 2020 - 06:40 AM

Ok Robin, thank you for those information.

Wait, see and estimate...



#10 robin_astro

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Posted 18 January 2020 - 07:07 AM

Currently 12.8 as measured by Itagaki so directly comparable with the 14.9  discovery magnitude

https://www.flickr.c...es/49401526653/


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#11 Aquarellia

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Posted 18 January 2020 - 10:04 AM

Currently 12.8 as measured by Itagaki so directly comparable with the 14.9  discovery magnitude

https://www.flickr.c...es/49401526653/

I agree with this value.

Visualy I estimate this SN between 12.6 and 13.0 this morning using Gaïa comparison values.

Michel


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#12 Rich (RLTYS)

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Posted 19 January 2020 - 04:16 PM

My observation of SN 2020ue based on my Slooh image taken on 1/18 is about 12.7. I used magnitudes from WikiSky.


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#13 Rich (RLTYS)

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Posted 19 January 2020 - 04:38 PM

I agree with this value.

Visualy I estimate this SN between 12.6 and 13.0 this morning using Gaïa comparison values.

Michel

Michel, where did you get your Gaia comparsion values from?



#14 Aquarellia

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Posted 19 January 2020 - 04:45 PM

Michel, where did you get your Gaia comparsion values from?

Easy, just from the star's info from SkySafari Pro.  I know this is not the best choice but better than no comparison, isn't it?  The AAVSO chart has only one comparison star (mag 14.3).

Michel


Edited by Aquarellia, 19 January 2020 - 04:53 PM.

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#15 robin_astro

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Posted 19 January 2020 - 05:47 PM

A low noise spectrum of SN 2020ue from last night using the ALPY 600 

 

sn2020ue_20200119_100_Leadbeater.png

 

Using SNID gives  exquisitely good detailed matches to several type Ia supernovae still a few days before maximum eg

 

sn2020ue_SNID_fit.png

 

Although the reported magnitude depends on the particular comparison stars and filters used, Gary Poyner's measurements over the last 2 days indicate it is still rising

https://britastro.or...55#comment-7755

 

Cheers

Robin


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#16 Aquarellia

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Posted 20 January 2020 - 12:24 AM

A low noise spectrum of SN 2020ue from last night using the ALPY 600 

 

attachicon.gifsn2020ue_20200119_100_Leadbeater.png

 

Using SNID gives  exquisitely good detailed matches to several type Ia supernovae still a few days before maximum eg

 

attachicon.gifsn2020ue_SNID_fit.png

 

Although the reported magnitude depends on the particular comparison stars and filters used, Gary Poyner's measurements over the last 2 days indicate it is still rising

https://britastro.or...55#comment-7755

 

Cheers

Robin

Whaw, what a good result!  

What is the reason of the ray near 6900 ?

Michel



#17 robin_astro

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Posted 20 January 2020 - 04:53 AM

 

What is the reason of the ray near 6900 ?

 

That is an O2 telluric band so absent in the reference spectrum.

The  broad absorption line at ~6100A is Si II,  the key identifier for Ia supernovae.  Its rest wavelength is 6355A but is redshifted by the host galaxy and blue shifted by the velocity of the material (approximately 13,500km/s currently)

 

Robin


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#18 robin_astro

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Posted 21 January 2020 - 11:33 AM

AAVSO have now published a chart with comparison stars

https://www.aavso.or...left&type=chart

 

Robin 



#19 Rich (RLTYS)

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Posted 22 January 2020 - 09:15 AM

It's about time, I've been looking for a chart since I started imaging this SN. waytogo.gif



#20 Aquarellia

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Posted 02 February 2020 - 04:10 PM

This SN magnitude stays high, my yesterday visual estimation : +12.3 +/- 0.2 using AAVSO chart.

Clear sky to you all

Michel



#21 Redbetter

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Posted 03 February 2020 - 04:41 PM

A few nights ago I observed it with an ST80 stopped down to 42mm.  I didn't do a magnitude estimate that night because seeing was very poor.  I had estimated it around 12.4 mag on January 22 (23 UTC) using the AAVSO chart when I observed it with the 20" and 60mm.  I don't think it was brighter a few nights ago, but like I said I didn't do an estimate because of poor seeing. 


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#22 Dave Mitsky

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Posted Yesterday, 03:07 PM

I observed SN 2020ue for the third time last night using the 17" f/15 classical Cassegrain at the Naylor Observatory.  I used magnifications of 170, 216, 259, and 324x.  For whatever reason, the supernova was more difficult to see than the first time I saw it, which was January 29th.


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