Comet 252P Zooms North, BA14 Grows Tail

Splintered comet duo 252P/LINEAR and P/2016 BA14 liven up both dusk and dawn this week. Naked-eye 252P finally debuts in northern skies, while BA14 makes a beeline through the Big Dipper. 

Green as Spring Grass

Comet 252P/LINEAR displays a vivid green coma from fluorescing gas in this photo taken on March 18, 2016, three days before perigee when the comet passed 3.3 million miles  (5.3 million kilometers) from Earth.
Gerald Rhemann

Get your ticket ready, the train's a comin'. Comet 252P/LINEAR, having passed closest to Earth on Monday, continues its dash north, finally poking above the horizon for the southern United States this week. Tomorrow morning (March 24th), skywatchers in the southern states can spot it just below the tail of Scorpius (nearly due south) shortly before the start of dawn.

Cloud vs. Cloud

Comet 252P/LINEAR passes by the Large Magellanic Cloud (small, diffuse object directly above it) on March 18, 2016.
Chris Wyatt

The following morning, it might be glimpsed as far north as Minnesota under excellent skies. By Saturday (March 26th), the entire United States and southern Canada will be in the clear with 252P nearly 10–20° high, depending upon your latitude.

If you're a beginner and don't quite know where to look, find a location with a wide-open horizon to the south and face that direction about two hours before sunrise. About 1/3 the way up from the horizon you'll see three bright "stars" arranged in a triangle. The top two are the planets Saturn and Mars, the bottom is the star Antares (see map below).

Both Mars and Antares have a reddish-orange color. Using Antares as a pointer, glide your gaze down the sloping tail of Scorpius until you reach the end, marked by the bright star, Lambda (λ) Scorpii (Shaula). Use this star as a stepping stone to reach the comet.

Recent reports from Southern Hemisphere skywatchers peg 252P at about magnitude +5.0, not a bright object but certainly naked-eye under good conditions.

Northern Comet Express

This map shows the daily position of 252P/LINEAR at 5:30 a.m. local daylight time for the Americas. Stars are shown to magnitude +6.5; sky for latitude 40° North. The comet passes just 2.4° west of M6, the Butterfly Cluster, on March 26th. Click for a larger version.
Stellarium / Diagram: Bob King

On March 18th, comet-watcher Michael Mattiazzo of Australia described it as 50′ across with a weakly condensed, somewhat brighter center. Glowing at magnitude +4.8, he spotted it with the naked eye, adding:

"Back in early March, when I found it a difficult object in an 8-inch scope, I was questioning whether 252P would even reach its predicted peak of magnitude 10. Never had I expected it to reach naked-eye brightness!"

Beautiful Black and White

Prefer a B&W reversed chart? Try this one, which shows the daily positions of 252P at the same time as the one above. Stars to magnitude +6.5.
Chris Marriott's SkyMap

Another Australian observer, Chris Wyatt, found it slightly brighter at +4.5, very diffuse, and about 40′ across through 7×50 binoculars on March 21st. The comet's sudden rise to prominence may be due to several factors: its close flyby of Earth just a week after reaching perihelion on March 15th certainly played a role, but the steep increase was unexpected and may point to an eruption on the comet that exposed fresh ice and dust to the Sun. Time exposure photos show a bloated ball of green mist from fluorescing diatomic carbon, a carbon vapor "exhaled" by active comets and set to glow by solar UV light.

Deeper for a Fainter Comet

If Comet 252P/LINEAR is fainter than expected or fades quickly, use this deeper and enlarged chart that shows stars to magnitude +8. The view is facing south around 5:30 a.m. local daylight saving time. Saturn or Theta Ophiuchi are good places to begin your star-hop to the comet.
Chris Marriott's SkyMap

So that's the good news. Ready for the bad? In one of the finest examples of wretched timing, a bright waning gibbous Moon takes up residence in the morning sky this week. Given 252P's diffuse appearance, most of us may need binoculars to coax it from the moonlight-soaked sky. Even worse, the Moon draws closer and closer to the comet through March 30th. Not until March 31–April 1st, when 252P/LINEAR is expected to fade to magnitude +6–7, will we finally get to see it in a dark sky.

Let's hope the comet hangs in there. Occasionally, a periodic comet will exhibit perihelion asymmetry, when its decline in brightness due to increasing distance from the Earth and Sun is delayed. No one's sure why this happens, but it may have to do with solar heat still working its way through the comet's nucleus, setting off additional waves of vaporization and dust outflow. If this happens with 252P, there's still a chance it will be faintly visible with the naked eye when the Moon departs.

Runaway Comet

On March 20, 2016, Comet P/2016 BA14 still appeared stellar but had brightened to magnitude +13. The comet is likely a fragment of 252P/LINEAR that broke away and now travels on a separate but very similar orbit.
Gianluca Masi

Meanwhile, the possibly related comet, P/2016 BA14 (Pan-STARRS), remains faint and almost coma-less. Photographs show a very small, nearly stellar object. Another Australian comet watcher, Paul Camilleri, used a 16-inch (0.41-meter) Dob at 260× to track the comet when it passed near a bright star on the 22nd. He described it as "stellar in appearance, magnitude +12.8; motion was such that you could watch the star-like comet move against the moonlit background sky and field stars."

Finally Some Fuzz

Comet P/2016 BA14 has been showing weak activity in photos taken this week. In this image made on March 22, a short tail extends southeast of the stellar coma.
Alfons Diepvens

On March 22nd, Belgian amateur Alfons Diepvens succeeded in photographing an extremely faint, 1′-long tail pointing southeast of the stellar coma using a 7.9-inch (20 cm) refractor. Other amateurs have also noted weak activity despite the bright moonlight of recent nights.

The comet's closest approach occurred yesterday (March 22nd), but it's still loping across the sky at practically a constellation a day. To get a sense of its movement, check out this animation by Greg Hogan of Kathleen, Georgia. The tracking map below shows BA14's hourly positions beginning at 0 UT March 24th (7 p.m. CDT March 23rd) through March 26th.

I suspect parallax may shift the comet's track just a bit as viewed from various locations because of its proximity to Earth. To plot a custom path for your city, go to the Minor Planet &Comet Ephemeris Service and type in P/2016 BA14 in the big, empty box. Next, scroll down and enter your latitude and longitude, then select your sky-charting program from the list near the bottom and click on Get Ephemerides/HTML page. Save the file of orbital element file that pops up and place it (or copy and paste) into the appropriate folder in your program. Open your program, select the comet and create a chart.

On a Tear

This map plots Comet P/2016 BA14's hourly progress starting on March 24th 0 UT (upper right) through March 26th. I've labeled brighter and helpful guide stars along the comet's path. Stars shown to magnitude +11. Click to enlarge and print out for use at the telescope.
Chris Marriott's SkyMap

The comet will undoubtedly prove challenging, but on the plus side, its fast movement will set it apart from everything else. When seeking it, focus on a brighter star the comet is expected to pass and then lie in wait for it to enter the view. If BA14 remains bright enough to spot in amateur scopes beyond the weekend, I'll create a new map and post it to the blog on Sunday.

Dual Flybys

Comet 252P/LINEAR safely flew past Earth on March 21, 2016, at a range of about 3.3 million miles (5.2 million kilometers). The following day, comet P/2016 BA14 did the same but at a distance of about 2.2 million miles (3.5 million kilometers), in what turned out to be the third closest comet observed to approach Earth after Lexell's Comet (1770) and 55P/Tempel-Tuttle (1366). 
NASA / JPL-Caltech

Both of these objects are very small. 252P is approximately 750 feet (230 meters) wide, or several hundred feet smaller than the lake freighters and cargo ships that ply the ports of the U.S. Great Lakes. BA14 is only about half as big.

A New Meteor Shower?

Peter Jenniskens of the SETI Institute and Jeremie Vaubaillon of the Institut Mécanique Céleste et de Calcul des Éphémérides (Paris), report that in the wake of 252P's close approach on March 21st, a new meteor shower may radiate from the constellation Lepus (below Orion) on March 28–29th. The shower, predicted to be weak, would originate from a diffuse cloud of meteoroids released by the comet between 1894 and 1926. Keep watch early in the evening before Lepus sinks too low.

A potential meteor shower, two fast comets, and a dwindling moon — our Easter baskets are quickly filling up!

10 thoughts on “Comet 252P Zooms North, BA14 Grows Tail

  1. Joe StieberJoe Stieber

    The caption for the initial 252P finder chart says “5:30 a.m. CDT (add 1 hour for Eastern, subtract 1 hour for Mountain, and subtract 2 hours for Pacific).” For those of us in the USA, it should simply say 5:30 am local daylight time. If those of us in the Eastern time zone looked at 5:30 am + 1 hr = 6:30 am, the sky would be getting bright from twilight while those in the Pacific time zone would be looking at 5:30 am – 2 hr = 3:30 am, when the comet would be noticeably lower in the sky, only a couple of degrees altitude on March 25th. The comet itself will not have moved substantially with respect to the background sky during the three-hour span between Eastern and Pacific times (at least not for a binocular or naked-eye observer). I’m hoping the weather over the next days allows me an opportunity to spot 252P. BTW, I should also note that like all of your articles, this one is top notch!

    1. Bob KingBob King Post author

      Thanks Joe – I overthought this one! You’ll see it changed now. I was just concerned that between one end of the country and the other, the comet would have moved a small amount. Thank you.

    1. Joe StieberJoe Stieber

      We finally had a clear morning on March 31, 2016, so I headed to the New Jersey Pinelands to look for 252P. I had already tried and failed a couple of times (closer to home), mainly due to cloudiness coupled with the gibbous moon. Anyway, shortly after arrival on March 31, I found the comet a couple of degrees above Xi Serpentis using 16×70 binoculars. I subsequently saw it with 10×50 binoculars. In both cases, the coma was dim and required careful inspection to see it (the third-quarter moon was only 15 degrees away from 252P). I’m looking forward to seeing it in a moon-free sky, but this morning (April 1) it was cloudy/rainy, and the forecast for the next couple of days isn’t favorable.

      1. docent

        Been looking for 252P with my 20 x 80 binos. One website, indicates this comet is between 5-6 mag.
        Another is reporting 12 mag. If you found it (Joe Stieber) with our 16×70 binos, I would assume it is
        between 5-6 mag. Any updates on where to find in on April 2nd?

  2. SNH

    Great article Mr. King. Because of the utterly horrible timing of the waning gibbous moon passing right through the are of 252/LINEAR at the end of March, I didn’t bother to try and see it until the morning of April 1st. What I found then was a large, bright glow 0.25 degrees wide in my 7×35 binoculars. It wasn’t until the morning of the 3rd that I looked at it again. This time the comet was higher in the sky before the moon was scheduled to rise. I was able to easily see it naked eye and put a magnitude rating of about +5.9 on it! What a surprise!

    1. Bob KingBob King Post author

      Thank you, SNH! I also finally got my first good look on April 1. Still waiting for a clear morning without moonlight and hoping the comet remains a naked eye object. Thanks for sharing your observation.

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