Tag Archives: C/2011 L4 PANSTARRS

Comet PANSTARRS for die-hards

Posted on by
8

Comet PANSTARRS climbs toward the North Star through Cepheus the King in the coming nights. It passes close to Gamma Cephei May 12-14, making it easy to find. Click map for a completely updated finder map and more details. Stellarium

Some of you have asked about a new map for locating famed Comet L4 PANSTARRS as it treks through Cepheus headed for the North Star. Well, here ya’ go. PANSTARRS currently shines around magnitude 7 and should still be easily visible in 50mm or larger binoculars as a faint fuzzy spot with perhaps a hint of tail. The comet’s visible all night long for observers at mid-northern latitudes. Share your impressions with us via Comments if you see it.

Will Comet L4 PANSTARRS live up to expectations? A reality check

Posted on by
15

Comet C/2011 L4 PANSTARRS passes near the globular cluster NGC 6541 on the morning of Jan. 16, 2013 as photographed from Castlemaine, Victoria, Australia. The comet measures about 2 arc minutes in diameter with a 7-minute long tail. Click to see more southern comets. Credit: Michael Mattiazzo

Sometimes that shiny new phone or car doesn’t quite live up to expectations, but we often  overlook their deficiencies and make our peace. We may have to do the same with Comet L4 PANSTARRS.

Observers in the southern hemisphere have watched the comet closely since it emerged from the solar glare last month. It’s presently loping along through Corona Australis the Southern Crown and visible shortly before dawn for those living down under. Not too many months ago, PANSTARRS was forecast to reach a brilliant magnitude 0 (equal to the star Vega) come early March this year. In recent weeks however, the comet has been lagging.

Amateur astronomers have noticed that its rise in brightness has been slowing down or plateauing of late. As of Jan. 19, 2013 the comet is a small, dense fuzzball of about magnitude 8 with a short tail pointing west. Binoculars show it as a dim glow.

With less than two months to go before the “big show”, this lag has made some ardent comet watchers revise their expectations of just how bright PANSTARRS will become.

Lightcurve of Comet C/2011 L4 PANSTARRS. Each black dot represents an observation of the comet. The bottom line (axis) shows time, the vertical axis, brightness. PANSTARRS is clearly getting brighter over time but not as fast as expected. Credit: Seiichi Yoshida

Seiichi Yoshida, a Japanese amateur astronomer who maintains the excellent and most useful Weekly Information about Bright Comets site, originally pegged the comet at magnitude 0 in March but has now revised his lightcurve (graphical representation of a comet’s rise and fall in brightness) to show PANSTARRS topping out closer to magnitude 3 at best. His estimate is based upon past as well as the most recent observations.

Comet L4 PANSTARRS photographed on Jan. 19, 2013 with a 200mm lens and time exposure. Credit: Rob Kaufman

If this holds true, what does it mean for comet watchers? A magnitude 3 comet is 15 times fainter than one shining at mag. 0. While still visible with the naked eye, such a comet would not be a visual spectacle. Given that PANSTARRS will be brightest when relatively near the sun in evening twilight, it would appear faint without optical aid, but still be a stirking sight in binoculars and telescopes.

Of course this could change again, so I wouldn’t get too worried yet. Comets are wonderful to follow in part because of their unpredictability. L4 PANSTARRS may yet have a few tricks up its sleeve. Stay tuned for more updates in the coming weeks.

Hergenrother: Mouthful of a comet worth the bother

Posted on by
Reply

168P/Hergenrother displays a bright nucleus (center of the comet’s activity), a blue, elongated coma (its atmosphere) and short tail on Oct. 3, 2012. Credit: Michael Jaeger

The title is my desperate attempt to find a rhyme for this comet’s wonderful name. While I may not have succeeded, that doesn’t change Hergenrother’s status as the coolest comet in amateur telescopes right now.

With the moon out of the sky, the next few weeks are ideal for those with 6-inch and larger scopes to pursue 168P/Hergenrother, currently the brightest comet visible at mid-northern latitudes.

Thanks to a recent outburst of activity, this fuzzy interloper shines around magnitude 9.5. It’s in a very handy spot, too, located not far from the upper left star in the familiar Great Square of Pegasus. The Square is well up in the southeastern sky by 9 o’clock local time.

Finder chart showing the comet’s nightly position starting Oct. 5 at 9 p.m. (CDT). Hergenrother moves across the northeastern half of the Great Square. The star marked Alpha is Alpha Andromedae, which is shared by the Square. Stars shown to magnitude 9.5. Created with Chris Marriott’s SkyMap software

I’ve included a detailed chart for tracking the little comet. Look for a dense, fuzzy patch of light. Hergenrother has a bright head and short tail fanning south. Through my 15-inch scope at low power it was miniature spectacle last night. Hergenrother’s nucleus mimicked a fuzzy, bright “star” at the north end of a well-concentrated coma; a wispy tail blew back from the comet’s head like.steamy breath on a cold day. Beautiful!

C/2011 L4 PANSTARRS on September 9 from Australia. The comet was 11th magnitude at the time. It’s currently best viewed from the southern hemisphere. Credit: Michael Mattiazzo

Tracking comets will develop your observing skills and help you to recognize subtle features like the density of the coma, whether the nucleus is star-like or fuzzy and the length and orientation of the tail. You can then apply these skills to future comet chasing to better enjoy and appreciate how the character of these icy beauties changes as they approach and recede from the sun.

There’s much to chase. Next March C/2011 L4 PANSTARRS could shine as brightly as Sirius and display a long, feathery tail. Then in November 2013 C/2012 S1 ISON will pass near Earth after a close flyby of the sun with a potentially spectacular show in store.

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

Posted on by
54

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.

PANSTARRS – the next bright comet?

Posted on by
47

Comet C/2011 L4 PANSTARRS photographed on May 18. Credit: Ernesto Guido, Giovanni Sostero and Nick Howes

Last June astronomers at the University of Hawaii announced they’d discovered a comet with the 1.8 meter (70.7 inch) telescope atop Mount Haleakala as part of the Panoramic Survey Telescope & Rapid Response System or Pan-STARRS. The survey’s goal is to photograph the entire sky several times a month in search of Earth-approaching comets and asteroids that could pose a danger to our planet.

At the time, Comet C/2011 L4 PANSTARRS (or PANSTARRS for short) was extremely faint and nearly as far away as the planet Saturn.

After more observations pinned down the comet’s orbit, predictions showed it would pass perihelion – its closest point to the sun – at a distance of 28 million miles on the evening of March 9, 2013. That’s close enough to vaporize a lot of cometary ice, releasing the dust needed to form a bright coma and tail.

Just how bright, no one can be certain. We all know how unpredictable comets can be; the break up and fading of Comet Elenin is just one recent example. But estimates based on the PANSTARR’s distance from the sun and Earth at the time of perihelion put it at magnitude 0 or as brilliant as Vega or Arcturus.

Comet C/2011 L4 PANSTARRS will appear in the evening sky just days after perihelion. The date shown here is March 12, 2013 about 40 minutes after sunset. The ultra-thin crescent moon will lie just five degrees to the north of the comet. Maps created with Chris Marriott's SkyMap software

Circumstances for viewing a bright comet couldn’t be better. PANSTARRS pops into the evening sky only a few days after closest approach to the sun. Moving rapidly northward, it soon becomes visible all night long from mid-northern latitudes in April.

PANSTARR's orbit is steeply inclined (84 degrees). Right now it's below the plane of the solar system (dark blue) but after perihelion next March its orbit takes it quickly above the plane (light blue). Credit: JPL/NASA

You might be wondering why I’d bother writing a blog about something happening 10 months down the road. Let’s just say I want as many amateur astronomers as possible to have the opportunity to see the comet early.

Die-hard comet observers have been photographing and observing the comet since late this winter, more than a year before perihelion. I’ll take that as a good sign that PANSTARRS is on schedule.

I sought the comet a week ago using a 15-inch reflecting telescope and was surprised at how easy it was to see. Located near the bright star Antares in Scorpius the Scorpion, I estimated the comet’s brightness at magnitude 12.5 (at discovery it was 19 — faint!). PANSTARRS was a very small but dense knot of light about 20 arc seconds in diameter with a faint star-like center. Its compact appearance is a good indicator of lots of dust activity in the comet’s nucleus – another positive sign for the coming apparition. A second look this past Saturday morning showed it smidge brighter yet.

Use this map to help you find the comet in your telescope. Antares is at left and the head of Scorpius is outlined. The comet is low in the southern sky from mid-northern latitudes. Stars shown to about 10.5 magnitude. PANSTARRS look like a very small "cottonball" with a brighter center at medium and high powers.

If you start observing now, you’ll have the pleasure of watching Comet PANSTARRS brighten and develop on its journey to perihelion and beyond. Following a comet night by night can be very rewarding, comparable to studying a species of bird to better understand and appreciate its behavior. For the moment, you’ll need a 10-inch or larger scope and dark skies but as the weeks and months advance,  it will gradually brighten.

Skywatchers in mid-northern latitudes will be able to follow PANSTARRS through early August before it’s too low to view and lost in the glow of evening twilight. Our next opportunity won’t be until next March post-perihelion. Southern hemisphere observers will fare much better with the comet high in the sky and well-placed for viewing for months to come.

To assist you in your quest, either download comet orbital elements for your favorite star charting program at the IAU Minor Planet Center site  or use the map above which shows the comet’s position around 11:30 p.m. CDT every five nights. PANSTARRS is still 325 million miles from Earth or more than halfway to Jupiter.

Comet Hartley 2 photographed by NASA's EPOXI mission. The bowling pin shaped nucleus is about 1.2 miles long. Jets of material, from ice vaporized by the sun's heat, are being ejected from the nucleus. Credit: NASA/JPL-CalTech/UMD

Returning to the question of the comet’s brightness, that may depend on whether it’s making its first or hundredth trip around the sun. On a first swingby,  exotic ices of nitrogen and carbon dioxide, long preserved in the deep freeze of the outer solar system, vaporize at great distances from the sun, making the comet appear unusually bright. If we’re not careful, we might extrapolate that behavior to the time of closest approach and predict a very bright passage. Unfortunately, once those ices are gone, the comet may have only a modest amount of water ice remaining for the sun to vaporize and not brighten as expected when closer to the sun.

Three types of orbits are possible for bodies in the solar system. Most orbit in ellipses around the sun. Credit: Oracle ThinkQuest Education Foundation

Comets that return time and again all have elliptical orbits around the sun like the planets but more stretched out or elongated. Comet PANSTARRS’ orbit appears for the moment to be nearly parabolic. A parabola is a sort of open-ended ellipse with one end near the sun and the other a return trip to infinity. Most comets on parabolic orbits come from the far edge of the solar system and have their orbits reworked by giant planets Jupiter and Saturn into very long but closed ellipses with orbital periods of hundreds of thousands to millions of years. PANSTARRS might be one of those “fresh” comets and putting on a good show now despite its distance. We’ll have to just wait and see.