Two new supernovae for amateur telescopes are keeping things lively this month!

Supernova 2020jfo
The Zwicky Transient Facility discovered supernova 2020jfo in the bright galaxy M61 in Virgo on May 6, 2020 — the 8th supernova recorded in this galaxy since 1926. North is up.
Gianluca Masi

My gosh, the sky is so busy with comets right now, do we really need a bunch of distracting supernovae?

Yes! Good fortune has delivered two exploding stars to the evening sky, one a faint supernova in a bright galaxy and the other a bright supernova in a faint galaxy.

On the Rise

Location of M61
To find M61, a 10th-magnitude barred spiral, start at 4th-magnitude Eta (η) Virginis, then slide 4° north to 16 Virginis and from there 1.2° further north-northeast.

Let's start with SN 2020jfo since M61 is a bright, familiar face in the Virgo cluster. The supernova is located 66″ west and 29″ north of the nucleus, about 40″ due north of a similarly bright foreground star. When discovered on May 6th, it glowed meekly at magnitude 14.7, climbing to 14.3 by the 10th. Because the explosion was caught early on the object will likely continue to brighten in the coming weeks. Daniel Perley (Liverpool John Moores University, UK) and team took spectra of the new object, suggesting in a recent AstroNote that it's a "young Type II supernova" caught about 7 days before its peak brightness.

M61's spiral arms are studded with hundreds of bright nebulae (pink spots) where vast numbers of new stars are in the process of being born. The galaxy spans some 100,000 light-years, similar in size to our Milky Way.

The supernova is far from M61's blazing nucleus, gleaming bright and free in the galactic countryside. That makes it relatively easy to see compared to supernovae shrouded in the starry haze of their galaxies' cores. A 10-inch scope under dark skies should be able to handle this one. If it rises an additional magnitude, an 8-inch will do.

Supernovae in M61
Try to spot the three different supernovae in this time-lapse, cosmic version of "Where's Waldo?" They are 2006ov, 2014dt and 2020jfo.
Gianluca Masi

M61 itself is a beautiful barred spiral located about 52 million light-years away with a pinwheel of nebula-flecked arms and a bright, non-stellar core. It's also a starburst galaxy with an exceptionally high rate of star formation. Short-lived supergiant stars hatched within its myriad nebulae provide the fodder for regular supernovae. We've been enjoying the fireworks since the first supernova blew up here in 1926. Seven more followed in 1961, 1964, 1999, 2006, 2008, 2014 and now in 2020.

Supergiant Farewell

How a Supernova Explodes
As soon as a supernova progenitor ceases to produce heat, its Earth-size core collapses to about 20 kilometers and a torrent of neutrinos fly away into space. After the core reaches a density comparable to an atomic nucleus it bounces and causes a shock wave to speed outward through the overlying gas and to the star's surface, destroying the star in the process.
Steve Simpson / S&T

Type II supernovae like 2020jfo involve the sudden and violent collapse of a supergiant star when its nuclear fuel gas tank hits empty. With no heat and pressure in the core to battle back the crushing hand of gravity, the star implodes. The infall rebounds at the core, creating a shock wave of such ferocity that it rips through the star and blows it to bits in a titanic explosion 100 million times brighter than the Sun. No wonder we can see these things in our backyard telescopes!

Rockin' Bright

Supernova 2020hvf
In my 15-inch scope on May 12.1 UT, SN 2020hvf totally blew away its host galaxy NGC 3643. The galaxy is located about 95 million light years away. South is up. Click here for a photo.
Stellarium, combined with author's sketch

SN 2020hvf was discovered in the 14th-magnitude galaxy NGC 3643 in southern Leo on April 21st by the ATLAS Project, the same group that successfully spotted two comets in the spring sky. Located 21.9″ east and 2.7″ north of the galactic nucleus, the supernova was initially faint — only magnitude 15.5. But by early May it had climbed to magnitude 12.5, outshining not just the core but the entire galaxy! While NGC 3643 is only a faint, 13.5-magnitude smudge, its supernova absolutely rocks.

Location of NGC 3643
SN 2020hvf's host galaxy NGC 3643 hides in the backwoods of Leo not far from the 5th-magnitude star Tau (τ) Leonis. A suggested route to the supernova is shown in green, and the inset shows a magnified view.
Stellarium, with additions by the author

Supernova 2020hvf is a Type Ia event, where a white dwarf accretes matter from a nearby companion star until it exceeds the Chandrasekhar Limit (1.4 solar masses). The additional weight and pressure of the stolen material initiates runaway nuclear fusion within the dwarf and boom! — it explodes as a supernova. Type Ia supernovae are typically more luminous than Type IIs.

With no Moon to brighten the evening sky, the next two weeks are ideal for observing these new guest stars. How sweet life is to witness a catastrophic event in a distant galaxy and then return home to sleep soundly on a soft bed.


Image of Tom Hoffelder

Tom Hoffelder

May 15, 2020 at 3:41 pm

Supernovae! So many reasons to observe them! No supernovae, no people, no planets, no nothing, just stars. And so cool to see an individual "star" in another galaxy, some quite far away; my record with the C14 is 200 mly. On the 12th I did see 2020jfo, my 30th in the last 9 years, but I wasn't able to find the brighter one, main(e)ly because I'm pretty sure a bear was prowling around near me in our yard! Next time!

You must be logged in to post a comment.

Image of Bob King

Bob King

May 15, 2020 at 8:00 pm

And I suspect that bear was also made by a supernova. As amateurs astronomers we learn to respect nature big and small. Good luck the next clear night!

You must be logged in to post a comment.

Image of Steve Rusnak

Steve Rusnak

May 15, 2020 at 8:12 pm

Hi Tom,
I haven't seen as many Supernovae as you have but have photographed a few.
Mainly I am wondering if this is the same Tom Hoffelder that was the first president of the Treasure Coast Astronomical Society? I have a picture and although its about 40 years ago, looks like you. If so, I still have your book on star hopping, if not, keep observing those nova.

You must be logged in to post a comment.

Image of Tom-Reiland


May 26, 2020 at 4:36 am

Tom, I thought that I might miss out on these two SNs because of the weather and the operation to open up my artery with a stent on April 13. Finally got a decent night and I was able to open the roof for the 21" Reflector at Wagman Observatory tonight. The one in M61 was not difficult to find. Two foreground stars were pointing right at it. A little over half an hour later I found 2020 hvf as it formed an elongated triangle with two stars near 3643. These were the 114 and 115 SNs that I've observed going back to Gus Johnson's discovery of one in M100 in 1979 and the 47th since my discovery of the SN in M51 in early June, 2011. I made an independent discovery of the SN in NGC 7541 in July of 1998, but Lick Observatory beat me to it. Both SNs had the letter designation of dh. What an odd coincidence.

You must be logged in to post a comment.

Image of Marcelo-Barbosa


May 17, 2020 at 6:16 pm

Bob - Good article. It is not often that you get to see two supernovas in two different galaxies in one night.

I was able to visually spot both 2020 jfo and 2020 hvf with my C-14 last night. I was in west Texas and had good dark skies

High magnification certainly helped on both. 2020 jfo was relatively easy, especially given how bright M61 is. It was remarkable to see how 2020 hvf simply dwarfed it's host galaxy, just as you described

Will try to photograph them next, so wish me luck.

You must be logged in to post a comment.

Image of Bob King

Bob King

May 17, 2020 at 6:51 pm

Very happy you saw both! I share that same excitement. Good luck in your photography!

You must be logged in to post a comment.

You must be logged in to post a comment.