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Other relatively bright supernovae

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#1 StanH

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Posted 19 June 2017 - 05:10 PM

Besides SN 2017eaw in NGC 6946 there are currently a few other supernovae visible from northern areas in telescopes of 17.5-inch or possibly less.

SN 2017egm in NGC 3191 is superluminous (SNSL-I) or hypernova in NGC 3191 in Ursa Major.  I viewed it last night (June 18) and estimated it around magnitude 14.5.  At a glance the supernova/galaxy combination appeared as a fuzzy, but odd looking star.  With averted vision the supernova stood out east of center.  See http://www.astronome...org/?read=10498 for more information.

 

SN 2017ein in NGC 3938 is a peculiar Type Ic as it only reached around magnitude 15.1.  It is currently fading though.  It lies in Ursa Major.

 

SN 2017erp which is a normal Type Ia in NGC 5861 in Libra. It’s a bit south, but sufficiently high from my latitude of 37 degrees north.  It was an easy starhop from Beta Librae.  On the night of June 18 I estimated it to be around 14.3-14.4 (though an image I took later had it closer to 14.7V). It is currently on the rise and may reach magnitude 13.2.  Also viewed the galaxies NGC 5858, IC 1091, and NGC 5872 in the area. Of these, NGC 5861 was by far the largest.

 

MASTER OT J132501.00+431846.1 was initially thought to be a supernova near NGC 5145, but its quick fading is more indicative of a dwarf nova in our galaxy. It was about magnitude 14.5 a few nights ago, but may be too faint now to be detected in anything but large apertures.  Thus far there has not been a spectrum to my knowledge to determine its nature.

 


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#2 ssmith

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Posted 19 June 2017 - 09:49 PM

"MASTER OT J132501.00+431846.1 was initially thought to be a supernova near NGC 5145, but its quick fading is more indicative of a dwarf nova in our galaxy. It was about magnitude 14.5 a few nights ago, but may be too faint now to be detected in anything but large apertures. Thus far there has not been a spectrum to my knowledge to determine its nature."

Stan - This is good to know. I went out on the 16th to photograph it but caught only a wiff of it on my photos. Seemed way too dim to be at the reported 14.5 mag so I thought there may have been a problem with my equipment. Tried again last night and could not even duplicate my previous feeble success. Totally vanished.

Here is a photo I took of SN2017ein on the same evening.

image.jpeg

Edited by ssmith, 19 June 2017 - 11:32 PM.

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#3 stargzr66207

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Posted 20 June 2017 - 06:33 PM

Stan,

Supernova 2017eaw in NGC-6946 is definitely the cream of the current crop.  I took a look at 2017ein in NGC-3938 last night through my 14-inch f/4.5 Steve Swayze Dob under mag 21.4 skies (SQM-L reading).  It was a tough one, but with averted vision it could be held, close to the nucleus on the SE side. The galaxy itself looked great, with hints of two spiral arms, and a lot of mottling in the outer haze. I was observing at 80X (20mm Nagler II).

 

Ron Abbott


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#4 StanH

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Posted 20 June 2017 - 06:37 PM

Steve - the latest on David Bishop's page has it at 17.6 on June 18.

 

Forgot in my original post to include David's link for those who might not be aware of it:  http://www.rochester...y.org/snimages/

 

He does extraordinary work keeping information on supernovae together. 

 

The ASAS-SN team found one which could get to about magnitude 15.0 if it is a Type Ia before maximum.  It is AT 2017evn (ASASSN-17hz) in an SDSS galaxy.  This appears to be a relatively near dwarf galaxy with z = 0.017  https://wis-tns.weiz.../object/2017evn


Edited by StanH, 20 June 2017 - 06:41 PM.


#5 ssmith

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Posted 21 June 2017 - 07:27 AM

Here is a photo of SN2017eaw I took on the same night as SN2017ein above.


image.jpg
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#6 stargzr66207

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Posted 21 June 2017 - 01:12 PM

Here is an image of supernova 2017ein in NGC-3938 which I captured Monday evening the 19th.  Simultaneously, it was just barely visible in my 14-inch f/4.5 dob with averted vision.  It was VERY close to the core.

This image is 48 minutes of data (8X6-minute subs) thru my C-11 at f/2 using HyperStar.NGC3938SN360SecLtAnn.jpg

 

Ron Abbott


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#7 StanH

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Posted 21 June 2017 - 11:50 PM

Tonight I had plans for imaging and observing as I have the next two days off.  Thought I might get lucky and the cirrus runoff from thunderstorms to the west and the apparently leading edge of the tropical system would stay away long enough tonight.  Turned out to be a huge sucker hole. frown.gif

 

However, I did get a view of SN 2017erp in NGC 5861 in Libra.  Poor seeing and stars were more difficult than a few nights ago.  However, it seemed to be as bright as a 13.7 star to the east-southeast.  Wasn't able to image it as from where the imaging telescope was set up a tree was in the way.

 

Got a series on SN 2017ein in NGC 3938 through the thinner portion of the cirrus runoff before they got too thick.  It has faded to around 16.0V now.

SN2017ein NGC3938 June 21 2017

Edited by StanH, 21 June 2017 - 11:56 PM.

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#8 StanH

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Posted 24 June 2017 - 07:17 PM

SN 2017evn (ASASSN-17hz) was confirmed as a Type Ia some 7 days prior to maximum http://www.astronome...org/?read=10521.  There is about 0.1 magnitude of extinction in the direction so it could peak around magnitude 15.1.  Have not seen any updates on David Bishop's site nor have I been able to image it.

 

SN 2017exo (ASASSN-17ie) in IRAS  18294+1636 has also been confirmed as a Type Ia before maximum.  It has a similar redshift to that of SN 2017evn, but there is about 0.9 magnitude of extinction.  It would peak around 15.9.  I was able to image it tonight with a robotic telescope in Spain.  It measured 16.2.  The date on the image should read 2017 June 24.982.  Got a couple of numbers turned around.

SN2017exo

Edited by StanH, 24 June 2017 - 07:27 PM.


#9 Redbetter

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Posted 26 June 2017 - 07:17 AM

I observed SN 2017erp in NGC 5861 in Libra tonight.  This one was easy in the 20" in dark skies even before twilight was complete.  It was more luminous than I anticipated and likely in the 14.0 mag range or better. 

 

Since I was in the region I viewed another 6 NGC galaxies, an IC, and another four MGC/UGC/PGC's.   



#10 SNH

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Posted 26 June 2017 - 03:01 PM

Wow! Thanks a lot StanH for the supernova update. Most of the time David Bishop's sight has a couple ~+14.5 supernovas listed, but when I research them they're in the early morning sky, or too low, or in a galaxy that is so obscure I have trouble finding it! Because of your post though, I got out last night with my 10-inch SCT and saw three supernovas! I first saw SN 2017egm while it was only 31 degrees up in the NW, then saw SN 2017erp around 13th magnitude (I didn't have an AAVSO chart) and 38 degrees up, and finished my observations of supernova off with SN 2017eaw in Cepheus. I'm not familiar with the term "superluminous", so I will have to research that. You might be surprised that I could see all three, but I've seen magnitude +15.3 stars under my magnitude +7.1 skies!

 

Scott


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#11 StanH

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Posted 28 June 2017 - 04:42 PM

SNH, that is great!  Especially for seeing SN 2017egm.  Due to the rarity and usual extreme distances of superluminous supernovae, I suspect very few have actually been seen rather than imaged.  That was my thrill in seeing it and hoped more people would get a chance to see it.

 

Unfortunately, I have nothing further to report.  Haven't had the weather to get out.  Wanted to have a try at SN 2017evn (ASASSN-17hz) near peak to see if it brightened like I expected.  Pretty much used up my budget for robotic images this month so not able to follow up their either.



#12 StanH

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Posted 02 July 2017 - 05:41 PM

Another superluminous supernova has been discovered which is a little closer than SN 2017egm.  It is 2017faf (ATLAS17hpt) found in a dwarf galaxy at z = 0.029.  However, there may be significant reddening within the host.  https://wis-tns.weiz.../object/2017faf

 

AT2017fbu (ASASSN-17is) in IC 211 could get to about magnitude 14.0 if a type Ia,  A normal core collapse would be closer to 16.0.  No spectrum yet.  https://wis-tns.weiz.../object/2017fbu



#13 StanH

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Posted 03 July 2017 - 03:04 PM

Another superluminous supernova has been discovered which is a little closer than SN 2017egm.  It is 2017faf (ATLAS17hpt) found in a dwarf galaxy at z = 0.029.  However, there may be significant reddening within the host.  https://wis-tns.weiz.../object/2017faf

 

 

A second spectrum of SN 2017faf suggests it is not a superluminous supernova after all and it a Type IIb.  Furthermore, the significant reddening was not seen. http://www.astronome...org/?read=10554

 

Might not get bright enough to be seen visually, but might be interesting to follow with photometric filters.


Edited by StanH, 03 July 2017 - 03:04 PM.


#14 StanH

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Posted 11 July 2017 - 05:40 PM

MASTER-IAC reports of a transient found in the SAO galaxy NGC 474.  http://www.astronome...org/?read=10570.  The SDSS shows this to be a very perturbed galaxy with multiple rings or halos http://skyserver.sds...t=512&scale=0.4

 

Most likely if this proves to be a supernova prior to maximum it would be a Type Ia due to morphology of the galaxy.  A normal Type Ia could max around 13.0.  However, it could potentially be a subluminous Type Ia.  If so it would only get to about magnitude 15.0.



#15 StanH

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Posted 11 July 2017 - 08:37 PM

MASTER-IAC reports of a transient found in the SAO galaxy NGC 474.  http://www.astronome...org/?read=10570.  The SDSS shows this to be a very perturbed galaxy with multiple rings or halos http://skyserver.sds...t=512&scale=0.4

 

Most likely if this proves to be a supernova prior to maximum it would be a Type Ia due to morphology of the galaxy.  A normal Type Ia could max around 13.0.  However, it could potentially be a subluminous Type Ia.  If so it would only get to about magnitude 15.0.

Somehow I missed the prior ATel.  Also discovered on same day by DLT and was classified as a young Type Ia http://www.astronome...org/?read=10569

 

Should also add this is a morning object.


Edited by StanH, 11 July 2017 - 08:39 PM.


#16 StanH

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Posted 22 July 2017 - 03:42 AM

Viewed SN 2017eaw in NGC 6946 and got my first and probably only look at SN 2017fgc in NGC 474 tonight under subpar conditions as the sky was bright.  Don't have a sky quality meter.  Even at 3AM with the Milky Way passing right overhead it was rather poor.

 

Estimated SN 2017eaw at 13.2 to 13.3 as it seemed equally bright as the star closest to it which APASS has at 13.26V.

 

Estimated SN 2017fgc at 13.7 to 13.8.  It was well separated about 2' east of the core of NGC 474.  In the field to the north is an arc of stars of 13.54, 13.57, and 13.91 all V from APASS.  To me, the 13.57 star (middle star of arc) was the brightest of the arc.  The supernova seemed fainter than the 2 nearer stars, but brighter than the 13.9 star which was farthest from the supernova.  A magnitude 14.5 star some 2' east of the supernova was rather difficult.  Only a very small portion of the central region of NGC 474 could be seen.  Actually, NGC 470 to the west appeared larger.  It was oval in shape and about 1' long.

 

Did a lot of imaging tonight.  Haven't gotten NGC 474 processed yet.  For SN 2017eaw came up with 13.24 +/- 0.03 on the unfiltered stack with V as reference.



#17 Redbetter

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Posted 26 July 2017 - 08:38 AM

I stayed long enough at the dark site last night to catch SN 2017fgc in NGC 474.  This one can be a little disorienting since NGC 470 is brighter and larger looking than NGC 474.  NGC 474's larger size shown in Uranometria is mostly invisible to the eye so the visual impressions are reversed..  Only a small brighter central portion is seen in 474.  After doing a drift and realizing which one was preceding the star pattern made sense and the SN was easily observed.  NGC 470 also revealed some of its spiral structure. 


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#18 StanH

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Posted 26 July 2017 - 09:07 PM

Bob King used my image of SN 2017fgc for his recent S&T article http://www.skyandtel...ernova-to-boot/
 
It did measure 13.7V which is a relief as it supports my estimate of 13.7 to 13.8 visually. 
 
This morning I got a robotic image of SN 2017fqk in NGC 1137.  It is a little farther than NGC 474.  Unfortunately, it is apparently fading.  My image had it down to 17.8V.  https://www.flickr.c.../36145333566/. 

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#19 StanH

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Posted 27 July 2017 - 05:38 PM

SN 2017fra = ASASSN-17jq has the potential of reaching about magnitude 16.0 if not a hair more.   It lies in SDSS J153151.40+372445.8 which has z = 0.0300.  Normally, that would be just too for for even a Type Ia to reach 16.0.  However, in ATel 10601 http://www.astronome...org/?read=10601 it was determined to be a Type Ia of the SN 1991T variety some 8 days before maximum.  These can be slightly brighter than the typical Type Ia.  Assuming a peak magnitude of -19.5, negligible extinction, and a distance modulus of 35.5 that puts it right at 16.0.  

 

I took an image through iTelescope.net in Spain and it measured 16.3 with V as reference, which is brighter than 16.8 at discovery.  That puts it about -19.2.  If it still has about a week to rise, it might go up another 0.5 magnitude or more.  https://www.flickr.c...N07/35815567780

 

As the host galaxy is very faint and probably not visible except in extremely large telescopes, that should make it easier to pick out this faint supernova.  Unfortunately, the moon is a problem.  Perhaps a few days after full, this supernova may remain near magnitude 16.0.



#20 SNH

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Posted 01 August 2017 - 03:38 PM

Thanks for the heads up on SN 2017fgc, StanH! I got out on the morning of July, 31st and saw it along with Pluto, the nova in Scutum, SN 2017eaw, and comet C2017 O1 in my 10-inch SCT.

 

Scott


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#21 StanH

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Posted 11 August 2017 - 05:01 PM

Newest potentially bright supernova is in the southern galaxy NGC 7187 (declination nearly -33 degrees).  It was discovered by ATLAS http://www.astronome...org/?read=10633.  Being an S0 galaxy most likely it is a Type Ia.  If it is a normal Type Ia it could get to about magnitude 13.4.



#22 StanH

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Posted 12 August 2017 - 09:43 AM

Got a BVR series on AT 2017gah in NGC 7187.  It has not brightened much since the discovery by ATLAS.  No published spectrum yet, but due to the faintness, the colors, and the type of galaxy it is probably a subluminous Type Ia of the 1991bg type.  https://www.flickr.c...N07/36521374315



#23 Redbetter

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Posted 18 August 2017 - 09:56 AM

I took a look at NGC 7187's SN 2017 gah last night.  The SN itself was an easy spot, visible in direct vision at around 15th magnitude and all of my field stars were matched down to 16 mag.  The difficulty was in catching the galaxy between trees in the more light polluted segment of the sky.  The last time I tried it was already in the trees due south, so this time I caught it lower in the sky in the clear.  There are a number of other galaxies along the star hop path.  Last night I missed on the first try doing a quick sweep and caught the noticeably brighter/larger tilted spiral ESO 404-27.  Realizing the morphology and field were wrong I back tracked and hopped from ESO 404-31 to ESO-404-28 before landing on NGC 7187.  The main obstacle is the low declination.

 

I also targeted SN 2017 fvl in UGC 2358 way north in Cassiopeia.  This isn't a verifiable rewarding target visually since the SN is nearly a perfect bulls eye on the stellar core of a dim galaxy.  There is no separation to speak of, so detecting the core is detecting the SN.  I caught it just as the glow of the moon was beginning to brighten the sky before it rose.  It was already a week past maximum light on Aug. 6 (per ATel #10621) at 15.8 mag.  The body of the galaxy itself was apparent, but quite faint.  The core/SN was an AV object.   I managed to catch one other galaxy nearby, CGCG 326-4, before a brightening sky convinced me to call it a night.   


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