A new supernova in the bright galaxy M77 in Cetus is within range of amateur telescopes. Here's how to find it.
On November 24th, the DLT40 Survey picked up a 15th magnitude supernova in M77, a bright, barred spiral galaxy in Cetus located 50′ southeast of 4th magnitude Delta Ceti. Whenever a supernova is discovered in a Messier galaxy, I get excited. Messiers are among the closer and brighter galaxies and often host supernovae visible in smaller telescopes.
With an apparent magnitude of 9.6, M77 is easy to find in telescopes as small as 3 inches though a 10-inch or larger scope will be needed to ferret out this supernova — at least at the moment.
Designated 2018 ivc, the new supernova has brightened to about magnitude 14.5 and appears as a tiny pinprick of light 8.7″ east and 16.1″ north of the center of the galaxy along the edge of the bright inner disk. Spectroscopy reveals the "new star" as a Type II supernova in its early stages, implying that the object could brighten further. Not to throw water on the fire, but intervening dust within the galaxy has dimmed and reddened the explosion, so it's difficult to predict how bright it might become. One outlier observation from November 25th put it at about magnitude 13.6.
This is the first recorded supernova in M77 and though it looks like little more than a faint star in a telescope, the reality is we're witnessing the collapse and explosion of a highly evolved supergiant star. As you read this, debris from the blast is expanding outward at some 13,500 kilometers per second (30.2 million mph). For perspective, that's a little more than one Earth-diameter per second! Going along for the ride are the complex elements that were forged in the star's core and now released into space to seed future generations of stars and their planetary systems.
M77 lies 47 million light-years from Earth in Cetus. After all those years of travel, how fortunate that the light from the supernova arrived just in time to track it down without a bright moon and the galaxy well-placed for viewing during evening hours. To find it, start with Menkar (magnitude 2.5), the second brightest star in Cetus, and slide about 2° to the southwest to Delta (δ) Ceti. Set Delta off to one side of the low-magnification field of view and you should see M77 on the opposite side less than a degree to the southeast.
To dig out the stellar cinder I recommend increasing the magnification to 200x or higher and studying the location along the bright, inner disk for a stellar point — this will be the supernova. Never fear magnification — you may need to go north of 300x depending on whether 2018 ivc brightens further or not. If seeing is poor, it can be difficult to suss out the star in a bright, galactic environment. Try again on another night.
Coincidentally, the bright comet 46P/Wirtanen passes about 7° southeast of the galaxy on the nights of December 8th and 9th.
For updates, head over to David Bishop's excellent Latest Supernovae page and click on the 2018 ivc link. I'll also update this blog with additional information including my own observation of the supernova which I hope to make tomorrow night.
UPDATE Dec. 4: I finally had clear skies last night (Dec. 4.1 UT) and looked for the supernova. Unfortunately, it was still very faint — I glimpsed it several times at ~magnitude 15.0. Despite some estimates around magnitude 13, I don't believe this object ever brightened beyond ~14.5 magnitude. Normally, a supernova this close would have been an easy mark, but as described above, dust within the host galaxy likely contributed to its faintness.