Bright Supernova Discovered in “Fireworks Galaxy” NGC 6946

A brand new supernova in NGC 6946 is bright enough to see in modest-sized telescopes. Here's how to find it.

Live webinar, May 19th! If you're unable to view the supernova through your own telescope, Gianluca Masi will show the exploding star live online on his Virtual Telescope Project website on Friday, May 19th, starting at 4:30 p.m. CDT (21:30 UT). Be sure to check it out.
Here's blinking at you!

A possible new supernova was discovered overnight by amateur Patrick Wiggins in the spiral galaxy NGC 6946 in Cygnus. You can see it blink in photos taken in 2011 (no supernova) and on May 14th. The star is above and right of galaxy center.
Gianluca Masi

Last night, Utah amateur Patrick Wiggins discovered a possible bright supernova in the spiral galaxy NGC 6946 in Cygnus. If confirmed, 2017 eaw will become the 10th supernova found in this explosion-rich galaxy in the past century, reaffirming its reputation for fireworks of the grandest kind.

It was Wiggins's third supernova, and he found it by comparing a CCD image made on May 14.24 UT through his 0.35-m f/5.5 reflector near Erda, Utah, with one taken several years ago and another from May 12th. Nothing showed on either image, leading him to suspect a supernova.

To be sure, he watched the new object for over an hour to see if it moved. Faint asteroids have masqueraded as supernovae before, but this one didn't budge. Italian astronomer Gianluca Masi did a check for known asteroids in the vicinity and none were listed. For the moment then, it appears we have a brand new stellar blowup in our night sky.

Through a combination of good fortune and hard work, Wiggins happened to catch the star during the early stage of the blast. He estimated its magnitude at 12.8. Others have since confirmed the discovery and pinned the star's brightness at 12.6, bright enough to spot in telescopes as small as 6 inches!

10th supernova and counting

New possible supernova AT 2017eaw is shown at the tick marks. The object is located about 2 minutes northwest of the the galaxy's center. The galaxy got its "Fireworks" nickname for all its supernovae. More supernovae have now been discovered here than in any other single galaxy. 
Gianluca Masi

The new supernova is located 61″ west and 143″ north of the galaxy's nucleus at R.A. 20h 34m 44.24s, Dec. +60° 11′ 35.9″, not far from two stars of similar brightness indicated on the map. Although spectra have yet to confirm whether it's a Type Ia (white dwarf detonation) or Type II (a massive star collapsing and exploding), Wiggins's early catch likely means that AT 2017 eaw will almost certainly continue to brighten.

(Update, May 14: Good news! According to ATel #10376, a spectrum taken of the object "is consistent with that of a young type IIP supernova at one week before the maximum light." This means that our "new star" was a massive supergiant that is no more.)

Big picture view

NGC 6946, located at the border of Cygnus and Cepheus within a degree of the open cluster NGC 6939, climbs into the northeastern sky for easy viewing on May evenings. The galaxy shines at magnitude +9.5 in a rich star field and forms a nifty triangle with Eta (η) and Theta (θ) Cephei. Once you've found the galaxy in your telescope, use the map below to star-hop to the supernova. 
Stellarium

During the last supernova blast in 2008, SN 2008S hovered around magnitude 16 at best; the brightest explosion occurred in 1980 when SN 1980K peaked around magnitude around 11.4. Wouldn't that be nice if it happened again? Timing's perfect for viewing the star. By 10:30 p.m. local time from mid-northern latitudes, the galaxy is already 25° up in the northeastern sky, and the Moon doesn't rise till after midnight.

Star-hopping to your destination

You can use the bright triangle of stars on the southeastern edge of the galaxy to point you to the possible supernova (PSN) on the opposite side of NGC 6946. Star magnitudes are shown with the decimal omitted. North is up, west to the right. Click to enlarge and print out.
Map: Bob King, Source: Stellarium

I'll have additional news as it arrives in my e-mail. You can also check David Bishop's excellent Latest Supernovae site for fresh updates. Congratulations to Patrick! He joins a long line of Fireworks Galaxy supernovae discoverers, which includes American astronomer George Ritchey, inventor of the Ritchey–Chrétien telescope design, who uncovered the first stellar blast in the galaxy, SN 1917A, on July 19, 1917, and got the ball rolling.

Spinning into eternity

NGC 6946 is well-known to amateur astronomers. The magnificent pinwheel (type Sc spiral) is located 22 million light-years from Earth and was discovered by William Herschel in 1798. Clear skies and happy supernova hunting!
Jim Misti

How much time does it take a single individual to find a supernova? In an e-mail communication with Wiggins, I learned he had searched on 292 nights since his last discovery in June 2015. Each night typically involves taking more than 500 images and examining each one for a potential "new star." The patience, determination and sheer grit involved in amateur discovery in the context of today's robotic search programs is nothing short of heroic.

22 thoughts on “Bright Supernova Discovered in “Fireworks Galaxy” NGC 6946

    1. John -kramer

      Nice catch there Bruce if that is indeed the star. So a SN puts out so much energy, that its simply impossible to be visually detected prior to the event? So a nova may be more plausible simply because the host star is visible beforehand?

      1. Bob KingBob King Post author

        Hi John,
        Thanks for your e-mail. If there was any cause for doubt, that’s been removed. This just in – spectra of the object confirm it as a Type IIp supernova about a week before maximum.

    2. Bob KingBob King Post author

      Hi Bruce,
      It’s possible that faint star may be the SN progenitor but now we know the outburst is a supernova. A spectrum of the object — just reported this evening — fits a Type IIp explosion about a week before maximum light. Check the article for more details.

  1. Lesley

    I am cruising the roaring forties off the coast of Tasmania.
    Imagine my amazement when at 14/5/17 04:00 (14/5 14:00 UTC), I noted a bright new star at about 50 degrees from magnetic north towards the East from my position of 42 08.651 148 20.780.

    I happily calculated that the position was fixed as the earth rotated through 45 degrees and was likely a supernova. What a highlight of my time sailing the Southern Ocean 🙂

    1. Bob KingBob King Post author

      Hi Lesley,
      The sky must be dark in those roaring forties! I’m not sure what you saw last night, but this supernova requires a telescope since it’s much fainter than what the naked eye can see. Happy sailing!

  2. Lesley Jean Roberts

    I saw a bright new star – I can be convinced it was otherwise – but not just on the fact that others did not see it that brightly. It was the brightest object in the sky by many magnitudes (barring the moon).
    The star was not there early on 13/5/17 and was there early on 14/5/17. The morning of the15th had a light cloud, and based on the star’s brightness of the preceding morning, I expected it to shine through – but it did not – it was totally absent. The morning of the 16th had solid cloud cover and again I did not see it. I am keen to see what is visible tomorrow (16th) morning.

    I can provide my tracking notes, written into the ship’s log. My ships position is GPS accurate, however my star sights were using the crappiest hand held compass I have ever had the misfortune to utilise plus using my finger webbing to calculate declination. Not scientific but the best I had to hand.

    EST magnetic bearing declination my Lat My long
    04:00 070 025 42 08.651 148 20.780
    04:30 065 030 42 08.651 148 20.780
    0500 050 040 42 05.429 148 22 357
    0600 045 050 42 00.851 148 22.151
    0700 030 060 42 53.403 148 21.868

    Can anyone tell me, based on my position – was it possible?

    1. Bob KingBob King Post author

      Hi Lesley,
      Based on your description, position and direction I think I know what you saw. It’s most likely the planet Venus. Venus is brilliant and would appear low in your northeastern sky around 4 a.m.

  3. Tom-Reiland

    Bob, I was able to observe the SN tonight at Wagman Obs using the 21″ Reflector at 127X. Using the Thompson Supernova chart for NGC 6946, I estimated it at 13.4 mag. It wasn’t quite the brightness of a 13.2 mag star in the field. The galaxy was only 20 degrees above the NE horizon. It was rather easy to locate. I had memorized the field in and around the area of the SN over the past day and a half. I hope and expect it to start brightening. That would be similar to the SN I discovered in M51 in June of 2011. It faded slightly after discovery and then brightened. That might have been the last visual discovery of a Supernova.

    1. Bob KingBob King Post author

      Hi Tom,
      Wow – I’d forgotten that was your discovery. I thoroughly enjoyed following that one. Thanks as always for sharing your observation.

      1. Tom-Reiland

        Your very welcome. I almost nabbed one in Late July of 1998 in NGC 7451 in Pisces. I was at a friend’s farm in the country in SW Pennsylvania. I observed the galaxy on Friday night and there was a star near the edge of it, but I was fairly certain that it was a foreground star. The next night was cloudy, but Sunday night was clear. I checked it again and the star was still there, but there was a 14 mag star on the other side that wasn’t there on Friday night.
        I headed home on went to my computer to check on it. Lick Observatory had discovered the Monday before at 17 mag, but the notice didn’t go out until Saturday. I was disappointed and pleased at the same time. It proved that I could find an SN, with enough luck. A member of the AAAP and a friend of mine, Gus Johnson discovered the SN in M100 in April of 1979. That’s the first one that I observed. This latest was #91. Heading to Wagman Obs now. Hope you have clear skies tonight.

        1. Bob KingBob King Post author

          Thanks Tom. Wish I could report clear skies here, but rain and clouds rule. Let us know what you see. I hear that the AAVSO has a new chart out on the 2017 eaw.

  4. Patrick-Wiggins

    Nice to see others getting pictures of “my” supernova. At least that way I can see it. It’s been cloudy here since just after the discovery so I’ve not had a chance for a second look. Hopefully this weekend by which time it will be 1st magnitude, right? 🙂

      1. Raymond

        Thanks Bob. From IHOP site in the Sierras, did catch it on Friday night with my 8″ Dob. The SN seemed slightly brighter than the two mag 13 stars nearby.

  5. SNH

    Got my first look at the supernova and it is still hanging in there at about magnitude +12.9 – +13.0. The first good “northern” supernova of the year, Bob! Thank you so much for the article! Because of you, I’ve now seen my fourth supernova ever!

    Scott

      1. Raymond

        Yes indeed, a safe distance. Looking at the printout of your map above, we were noticing how the Supernova was at a similar position in 6946 as we are in our Milky Way. That had us imagining the Betelgeuse blowup…

  6. rocksnstarsrocksnstars

    I finally got to see it! After two months it has dropped less than one magnitude. Using our C14, I submitted an estimate of 13.3 to AAVSO on the 15th (02:45 UT on the 16th).

All comments must follow the Sky & Telescope Terms of Use and will be moderated prior to posting. Please be civil in your comments. Sky & Telescope reserves the right to use the comments we receive, in whole or in part, and to use the commenter’s username, in any medium. See also the Terms of Use and Privacy Policy.

COMMENT