Wassup with comets Hergenrother, L4 PanSTARRS and S1 ISON

168P/Hergenrother with its short but sweet tail pointing southeast continues to head north into Andromeda in the coming nights. This photo was taken on October 16, 2012 from Austria. Credit: Michael Jaeger

With Comet 168P/ Hergenrother still bright and perfectly placed high in the southeast at nightfall, I wanted to share an updated map for amateur astronomers with 6-inch and larger telescopes who’d like to track the comet. At around magnitude 9.5, it’s still the brightest fuzzball in the fall sky. For the next couple weeks, 168P will track from northern Pegasus into Andromeda as it slowly fades. Put it on your list of autumn night sky targets and you won’t be disappointed.

Comet Hergenrother’s position in Pegasus and Andromeda at 10 p.m. (CDT) nightly beginning Oct. 18. Stars are shown to magnitude 9.5 with the brighter ones labeled. Right click the image and save, then print a copy you can use at the telescope. North is up. Created with Chris Marriott’s SkyMap software

If you don’t see the comet this time around, you’ll have to wait 7 years for its return. Hergenrother is a short period  or periodic comet – one that orbits the sun in fewer than 200 years. That’s what the “P”  stands for in its name. Since its discovery in 1998 by American astronomer Carl Hergenrother, this feathery visitor is making its third observed trip. About 265 numbered periodic comets have been discovered to date. Unnumbered periodic comets number nearly 250.

Next in our comet lineup is comet C/2011 L4 PANSTARRS.  The “C” indicates a long-period comet or one that orbits the sun in more than 200 years. Two hundred? That’s nothing. L4 Pan-STARRS’s period is estimated at 110,000 years. Seeing it’s a once-in-a-lifetime experience for sure.

Comet C/2011 L4 Pan-STARRS sprouts a short tail in this photo taken on Sept. 9, 2012. Credit: Michael Mattiazzo

Right now, the comet looks like a small, dense cotton wad of light in southern Libra visible only from the southern hemisphere low in the west during early evening hours.

Pan-STARRS has plateaued at a dim 11.5 magnitude for the past few weeks, but is expected to slowly brighten through fall and winter. Northern hemisphere observers will have to be patient. We won’t spy it till next March because the comet will either be too near the sun or too low in the sky.

On March 9, 2013 , L4 PANSTARRS passes just 28 million miles from the sun. In the days before and after, solar heating will furiously vaporize ice and dust from its outer crust causing the comet to quickly brighten and develop a substantial tail. A few days later it pops into the evening sky and could shine as bright as -1 magnitude or nearly the equal of Sirius, the brightest star. That’s what the predictions say anyway. More information and a sky chart HERE.

Artyom Novichonok and Vitali Nevski at their observatory. The two discovered the comet in photos taken a half hour before dawn on Sept. 21, 2012.  Copyright: Vitali Nevski and Artyom Novichonok

At least we can see L4 Pan-STARRS with an 8-inch or larger telescope. Comet C/2012 S1 ISON at 17th magnitude dips way below the limit, though amateur astronomers using larger instruments and digital cameras have taken pictures of it. ISON was scooped up by Russian amateur astronomers Vitaly Nevski and Artyom Novichonok in the course of the work for the International Scientific Optical Network (ISON) Survey from near Kislovodsk, Russia on Sept. 21. I hope the two are eventually recognized for their discovery by having their names penned to the comet instead of a survey acronym. Other comets discovered during surveys have received the discoverer’s name. Why not this one?

S1 ISON creeps very slowly across the constellation Cancer in the morning sky this month and next and won’t become visible in typical telescopes until next September. On November 28, 2013, the comet passes just 800,000 miles from the sun. If it survives the encounter, it could become brighter than Venus and be visible in broad daylight. A few days after its near-death experience, ISON swiftly moves northward, becoming visible in both evening and morning skies.

Look closely and you’ll see a small, fuzzy coma around Comet C/2012 S1 ISON’s star-like nucleus in this photo taken Oct. 17, 2012. Credit: Rolando Ligustri

Ernesto Guido and the team of amateur astronomers at the Remanzacco Observatory in Italy have observed a large amount of activity in the comet’s nucleus this fall despite it being 558 million miles from the sun or farther than Jupiter. Mike Mattei, another amateur astronomer, reports that Earth will pass under the incoming leg of ISON’s orbit. If the comet is large and active, he predicts we could see an increase in meteor activity around January 14-15, 2014 spawned by dust cooked off the comet nucleus. Isonids anyone?

Though I’ve heard it’s possible ISON could rival the full moon’s brightness and become one of history’s “Great Comets” when it appears in both morning and evening skies in early December, I’m going to play the conservative card. I’ve been burned by a few comets that haven’t lived up to expectations, and besides, these creatures are unpredictable anyway. That’s their charm. It could easily be fainter or brighter, though the latter is preferable by far. More on the S1 ISON including sky charts HERE.

New comet C/2012 S1 (ISON) could be spectacular sight in fall 2013

Comet C/2012 S1 ISON was discovered on Sept. 21 in pictures taken with 15.7-inch reflecting telescope of the International Scientific Optical Network (ISON) in Russia. This photo was taken on Sept. 22. Credit: Ernesto Guido, Giovanni Sostero and Nick Howes

A new comet was discovered inching across Cancer the Crab in the morning sky may knock your socks off next fall. Based on a preliminary orbit, it could become a very bright object beginning in November 2013 for both northern and southern hemisphere sky watchers. C/2012 S1 (ISON), its formal name, was found by Russian amateurs Vitali Nevski and Artyom Novichonok of the International Scientific Optical Network (ISON), a network of observers who track man-made space debris.

When first photographed on Sept. 21 the comet was an incredibly faint 18.8 magnitude and appeared much like a star with only a “whiff” of a coma around its icy nucleus. It will slowly cruise through the constellation Gemini for many months while growing gradually brighter. And I do mean gradually. Even as late as next June, ISON will only shine at 14th magnitude; that’s scraping the bottom of the bucket for most amateur telescopes.

The situation improves next September when 8-10 inch scopes should pick it up as a small blob in Cancer around 11.5 magnitude. From late October through late-November, things get much cheerier with C/2012 S1 brightening sharply from 7th to 1st magnitude in the eastern sky at dawn. I’m sure I’ll be setting my alarm for a look Thanksgiving morning.

The sharply curving path of Comet C/2012 S1 (ISON) shown from mid-November through mid-December 2013. The comet will be only 1.1 million miles from the sun on Nov. 29. That’s only a little more one sun-diameter. Maps created with Chris Marriott’s SkyMap software

When closest to the sun at perihelion on Nov. 29 it’s predicted to shine a spectacular -7 magnitude or almost 10 times brighter than Venus. Before you say WOW, you need to know the comet will lie only 4.4 degrees north of the sun (very close!) on that date and probably be hidden in the solar glare. Then again, we might spy it in daylight through binoculars by taking proper precautions to keep the sun out of the field of view. Some of us saw the last daylight comet C/2006 P1 McNaught in January 2007 this way.

The comet will be visible low in the southwest just after sunset in bright twilight with an upward pointing tail. The numbers are its brightness or magnitude. For reference, Venus is -4.4, Vega is 0 and the Big Dipper stars are +2 or second magnitude.

A second round of excellent visibility commences immediately after perihelion as S1/ISON performs a  hairpin turn around the sun and banks north into Ophiuchus and Hercules in early December.

While the comet fades during this time, it’s likely to have a spectacular tail and be as bright as magnitude -4. Both hemispheres will get great views, with the northern favored as Christmas approaches. Indeed, northerners will see it at both dusk and dawn. The comet will pass nearest Earth at a distance of about 37 million miles in January 2014. On the 8th it will appear only 2 degrees from the North Star.

That makes two potentially bright comets in 2013 – the other is C/2011 L4 PANSTARRS. It’s forecast to shine as brightly as Vega next March. While I like what I see, it’s important to remember that comets don’t always perform as expected. Any prediction of a comet’s brightness is subject to change, sometimes radically. I’ve seen a few wax much brighter than expected, while others have gone nowhere but downhill. More needs to be known about C/2012 S1′s orbit before an accurate forecast can be made. Let’s just say things look very promising for now.

The Great Comet of 1680 over Rotterdam painted by Lieve Verschuier. Notice the lack of city lights. Some of the people are using cross-staffs to measure the comet’s altitude and tail length.

One other interesting tidbit about C/2012 S1 (ISON) is that its orbit appears very similar to the Great Comet of 1680 also known as Kirch’s or Newton’s Comet. The two may even be related. Kirch’s comet was discovered on November 14, 1680 by German astronomer Gottfried Kirch.  After passing extremely close to the sun, it brightened so much it was plainly visible to the naked eye in mid-afternoon in early December.

One eyewitness report described it as having a “very fiery tail” that stretched 70 degrees long or more than 2/3 the way from horizon to zenith. Newton was working on his great treatise “Principia” at the time and used the comet’s motions to test the predictions of his theory of gravity.

Will C/2012 S1 (ISON) become a Great Comet, too? I’ll look into my crystal ball when more data becomes available.