ATLAS Crumbles As New SWAN Comet Stirs Excitement

Once our hope of becoming a naked-eye object Comet ATLAS (C/2019 Y4), seen here on April 9th, is fading as its nucleus fragments. Chris Schur

You gotta love a comet. Wait. Let me rephrase. You gotta be crazy to love a comet. Their unpredictability can drive us nuts. We expect them to brighten as predicted but then they’ll stall or even bust apart and dissipate. But it’s that very unreliability that gives them their charm and affirms that change in the heavens is as certain as change on Earth. Not only that but new comets can come out of nowhere — exactly what happened with the exciting discovery of Comet SWAN (C/2020 F8). Sit tight. We’ll touch on this new object in just a moment.

We’ll begin with Comet ATLAS, discovered last December, was predicted to brighten to naked-eye visibility in May. Some astronomers cautioned at the time that it might also break into pieces and fade away as it approached the sun. Guess what happened? Earlier this month it began to shed fragments from its icy nucleus. While had been a spectacular brightening trend rapidly reversed, and ATLAS began to fade. The fragments drifted apart, spewing dust and ice, to create a train of  of fuzzy nuggets inside the comet’s head.

When the center does not hold! Over the past couple weeks several fragments have broken away from the main comet nucleus — likely the bright point at the far right in each frame — over the past couple weeks. The comet has also become noticeably elongated in telescopes. Gianluca Masi and Nick Haigh (lower left)

Although the comet is still visible in 6-inch and larger telescope as it wriggles across the northern sky it’s faded from magnitude 8 to 9.5. Instead of getting brighter ATLAS appears to be headed toward oblivion. While part or parts of the comet may survive its May 31st perihelion (closest approach to the sun) we’ll probably have to eat our hopes of seeing it with the naked eye or binoculars. In the past week I’ve examined it regularly in my 15-inch telescope. It looks like a soft, misty patch of haze with a stretched-out core. At 400x I see hints of the fuzzy fragments clearly shown in the photo above.

If you want to track down Comet ATLAS yourself, use this map from Sky & Telescope. Warning — it’s not particularly bright. Likewise, the comet is tracking across the large, dim constellation Camelopardalis the giraffe which has no bright stars to serve as easy guides. Still, with determination and the right instrument you’ll find it. Look soon though! The best viewing time is at the end of evening twilight when it first gets dark. The comet is located about halfway up in the northwestern sky.

On April 13th Comet SWAN (C/2020 F8) sported a bright, dense coma (the green cloud) and short, spiky tail. It should become visible without optical aid low in the dawn sky come mid-May. Rolando Ligustri

In the Nick of Time

Just as ATLAS is dissipating another comet has come to the rescue. Named SWAN (C/2020 F8) — after a specialized camera on the orbiting Solar and Heliospheric Observatory (SOHO) — it was discovered earlier this month by Australian amateur Michael Mattiazzo. Mattiazzo spotted it while browsing through SOHO images posted online. The comet is already 8th magnitude and viewable in binoculars but only for southern hemisphere observers at the moment. Come early May it will ease into the dawn sky in the constellation Pisces then move rapidly eastward through Triangulum and Perseus as it brightens from about magnitude 6 (naked-eye limit) to 3.5! From mid-May into June will be prime time viewing for northern hemisphere observers when the comet will be located low in the northeastern sky at the start of dawn.

This map shows the path of Comet SWAN nightly through May, when it will shine brightest and become visible in the northern hemisphere. Its position is marked for 0h UT (Greenwich Time) every three days. 0h UT is the same as 7 p.m. Central Time the night before, so U.S. observers should remember to subtract one day from the dates shown. I’ll provide more detailed maps as we get closer to that time. Stars are shown to magnitude 6.5. SkyMap software

Of course there are caveats. Throughout its run, SWAN will never rise very high before the light of dawn interferes. That means you’ll have to be out at the right time to see it at its best … and carry along a pair of binoculars for assistance. I’ll help with updated maps, news and occasional humorous anecdotes in the weeks ahead. Should the comet live up to predictions it will be dimly visible at dawn without optical aid and a fine sight in binoculars.

Comet PanSTARRS wags a short tail on April 12th. The comet is faintly visible in binoculars right now. Sean Walker / MDW Sky Survey

“Old Faithful”

Meanwhile, Comet PanSTARRS (C/2017 T2) has been plugging across the northern sky for weeks. Ugh! It’s also in Camelopardalis — thankfully not for long. The comet inches closer to the bucket of the Big Dipper each night which will make finding it much easier.

Use this map to find Comet PanSTARRS through June 24th as it travels toward the Big Dipper. Positions are marked every 5 days at 7 p.m. CDT (0h UT). The best viewing time is early evening. The comet passes near the bright galaxy pair M81-M82 from April 20-25.Its position is marked for 0h UT (Greenwich Time) every three days. 0h UT is the same as 7 p.m. Central Time the night before, so U.S. observers should remember to subtract one day from the dates shown. Stars are shown to magnitude 8. SkyMap software

From a dark sky PanSTARRS is visible as a faint, fuzzy blob in 10×50 binoculars. Through a 6-inch scope you’ll see a round, misty glow with a brighter center and might even glimpse the central pinpoint of light called the false nucleus (the real one is very tiny and obscured by dust). Larger telescopes reveal a short, brush-like tail pointing southeast.

PanSTARRS will remain around magnitude 8 through the remainder of April and May, presenting many opportunities for you to grab a look. Best viewing time for late April is during the first half of the night from the onset of darkness until around midnight. Like the two ATLAS comets it’s also in the northwestern sky and up all night from many mid-northern latitude locations.

ATLAS, Take 2

Oh, and that’s not the end of it. A reader reminded me that a second Comet ATLAS (C/2019 Y1) has stubbornly refused to fade away despite predictions to the contrary. I checked it out last night (April 15-16) and was surprised to see it binoculars next to the W of Cassiopeia low in the northern sky at nightfall. Just a tiny ball of fuzz, but in the telescope it was bright — magnitude 8.5 with a small, dense coma and faint tail pointing north. I even saw hints of green!

This map will help you find Comet ATLAS (C/2019 Y1) as it moves north. Like the other ATLAS and PanSTARRS this comet is circumpolar for mid-northern latitudes and remains visible all night long. Its position is marked for 0h UT (Greenwich Time) every three days. 0h UT is the same as 7 p.m. Central Time the night before, so U.S. observers should remember to subtract one day from the dates shown. Stars are shown to magnitude 8. SkyMap

ATLAS Y1 was discovered in December 2019 and hugged the horizon until recently. Watch for it to sail across the northern sky toward the Big Dipper in the coming weeks while slowly fading. It passes just 6.5° from the North Star on May 1st. While faintly visible in binoculars a 6-inch telescope will show as a glowing blob of light.

With all the exciting news about comets I don’t miss a clear night anymore. Sometimes nature just piles it on!

8 Responses

  1. Edward M Boll

    I know experts can be wrong. Dr Batasms who predicted the demise of Y4 has stated that it is early on, but it kid likely that Swan is in outburst and will too fade away before perihelion. Maybe, he likes to take a pessimistic prediction. I sure hope his educated guess is wrong this time.

    1. astrobob

      There are some signs of life but the comet has been fading for a while now … thank goodness only slowly. It looked quite weak last night in the 15-inch. The only thing keeping its magnitude up is the size of the coma. Otherwise it’s on the dim side.

  2. Edward M Boll

    I have good news about F8. I checked recent observations. It has been seen with 7 power binoculars at magnitude 7.7, so far so good. Y4 reached mag 7.4, and was seen in 9 power binoculars. Charles Morris called it mag 6.9.

    1. astrobob

      Hi Edward,
      Thanks! I’ve heard the same for F8, but Morris’s estimate seems off for Y4 unless it suddenly brightened up in the past 12 hours. I saw it last night at 11 p.m. and it was a little
      brighter (with a longer tail) but I gave it magnitude 9. Are you sure you don’t mean Y1, though 6.9 seems overly bright.

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