Monday, September 24, 2012

New Comet: C/2012 S1 (ISON)

Cbet nr. 3238, issued on 2012, September 24, announces the discovery of a new comet (discovery magnitude 18.8) by Vitali Nevski (Vitebsk, Belarus) and Artyom Novichonok (Kondopoga, Russia) on CCD images obtained on Sept. 21.06 UT with a 0.4-m f/3 Santel reflector of the International Scientific Optical Network (ISON) near Kislovodsk, Russia. The new comet has been designated C/2012 S1 (ISON). 

Comet C/2012 S1 (ISON) will get to within 0.012AU of the Sun (extremely close) at the end of  November 2013 and then to ~0.4AU from Earth at the beginning of January 2014! According to its orbit, this comet might become a naked-eye object in the period November 2013 - January 2014. And it might reach a negative magnitude at the end of November 2013.

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 24 unfiltered exposures, 120-sec each, obtained remotely on 2012, September 22.4 from H06 (ITelescope network near Mayhill, NM) through a 0.25-m, f/3.4 reflector + CCD, shows that this object is slightly diffused, with a 5" coma. The FWHM of this object was measured about 15% wider than that of nearby field stars of similar brightness.

Our confirmation image (click on the image for a bigger version):

Below a false colour rendition of our image, better showing the coma (click on the image for a bigger version):

Below you can see an animation showing the movement of the comet in about 30 minutes (click on the thumbnail for a bigger version):

M.P.E.C. 2012-S63 assigns the following nearly parabolic (e = 0.999999964) orbital elements to comet C/2012 S1 (ISON): T 2013 Nov. 28.87; e= 0.99; Peri. = 345.56; q = 0.012 AU; Incl.= 62.36. (prediscovery observations were identified by G. V. Williams in MPC data from the Mount Lemmon Survey on 2011 Dec. 28 and from the 1.8-m f/4 Pan-STARRS reflector on 2012 Jan. 28)

Below you can see the orbit (Credit JPL) and current position of comet C/2012 S1 (ISON). The comet is at present of magnitude ~18 and it is located at 6.25 AU from the Sun. 

Below you can see a graph generated using the software Orbitas and showing the predicted magnitude (in red) versus the elongation (click on the image for a bigger version):

Below a star map (calculated for Latitude is 46 deg north, time about 45 minutes before sunrise) for 2013, Nov.10. showing the comet position (click on the image for a bigger version):

While by clicking here, you'll see a daily animation from 2013, Nov. 10 to Nov. 25 (wait a few seconds for the video to load).

Ephemerides (for the geocenter) generated using the "Minor Planet Ephemeris Service" for the period November 2013 - December 2014. A word of caution: as always with comets, the future magnitudes reported here are only indicative at this stage. Next weeks will tell us something more about the future of this promising comet.

Date       R.A. (J2000) Decl.    Delta     r     El.    Ph.    m1                                                                          
2013 11 10 12 08 03.9 -01 01 00   1.003   0.768   45.3  66.5   4.9
2013 11 18 13 24 14.0 -10 43 12   0.871   0.528   32.2  86.2   2.9
2013 11 21 14 01 42.1 -14 51 28   0.856   0.423   25.3  95.1   1.9
2013 11 22 14 15 23.6 -16 13 08   0.856   0.386   22.7  98.2   1.5
2013 11 23 14 29 42.5 -17 32 40   0.860   0.346   20.1 101.2   1.1
2013 11 24 14 44 40.4 -18 48 53   0.868   0.304   17.4 104.1   0.5
2013 11 25 15 00 21.0 -20 00 30   0.880   0.260   14.6 106.9  -0.1
2013 11 26 15 16 52.8 -21 05 50   0.898   0.211   11.6 109.2  -1.0
2013 11 27 15 34 37.4 -22 02 15   0.922   0.156    8.5 110.4  -2.3
2013 11 28 15 54 44.1 -22 42 33   0.955   0.090    5.0 107.8  -4.6
2013 11 29 16 23 20.6 -20 31 20   0.985   0.022    1.3  93.0 -10.6
2013 11 30 16 22 02.5 -16 36 54   0.917   0.108    5.0 127.2  -3.9
2013 12 01 16 19 50.9 -14 12 38   0.872   0.170    7.8 128.2  -2.0
2013 12 02 16 18 02.1 -12 08 28   0.834   0.223   10.4 127.5  -0.9
2013 12 03 16 16 32.0 -10 12 48   0.801   0.271   12.8 126.3  -0.2
2013 12 06 16 13 22.7 -04 40 04   0.716   0.395   19.9 122.2   1.2
2013 12 07 16 12 40.2 -02 48 06   0.692   0.433   22.2 120.7   1.6
2013 12 08 16 12 06.2 -00 53 51   0.668   0.468   24.5 119.1   1.8
2013 12 09 16 11 39.8 +01 03 27   0.646   0.503   26.9 117.5   2.1
2013 12 20 16 13 50.5 +28 33 54   0.467   0.829   57.1  94.7   3.5
2013 12 21 16 14 41.8 +31 45 29   0.457   0.855   60.3  92.1   3.6

by Ernesto Guido, Giovanni Sostero & Nick Howes


Anonymous said...

Is this something we should be very concerned about ? Could it cause a catastrophic event ?

Unknown said...

Doubtful. It's been stated that it will approach very close to the sun, not Earth. But, they haven't been specific about how close to Earth it will get, nor how large it is.

Stephen said...

Nope. Not a concern.

Anonymous said...

It appears to be the promise of a cosmic show, not a doomsday event...

Anonymous said...

"Comet C/2012 S1 (ISON) will get to within 0.012AU of the Sun (extremely close) at the end of November 2013 and then to ~0.4AU from Earth at the beginning of January 2014!"

~0.4AU is nearly half the distance between Earth and the sun. I wouldn't consider it a threat if the orbit calculations are correct.

Anonymous said...

It will pass about 0.5 AU from Earth -- half the distance between the Earth and Sun.

Anonymous said...

.4 AU is quite a distance [though not for visibility... for that, it is quite close]. But it might be interesting to recalculate the orbits using the Parker-Sochacki solution to the Picard iteration , and including the orbits of the planets, the relativistic effects as it goes around the sun, and ??? I dunno if the steam jets would affect the orbits or not, but possibly see how much variation that would generate. The nice thing about Parker Sochacki is that it makes multi-body orbital calculations a lot easier.

sky guy said...

We will be in for a VERY good show since we've not seen a comet pass this close to the sun and earth in a long, long time. I just hope the crazies don't latch on to ISON and make stupid predictions.

Kevin Heider said...

1. The apparent magnitude of a comet has a lot to do with the viewing angle from the Sun. C/2012 S1 (ISON) will only be brighter than Venus when the comet is less than 5 degrees from the Sun in the sky. If the comet does not disintegrate, I do have high hopes that the dust tail will extend far from the Sun/comet.

2. The orbit of the comet (thanks to precovery images in Dec 2011 and Jan 2012) is already determined well enough to know that the comet will safely pass somewhere from 0.42AU to 0.44AU from the Earth. That is almost half the distance to the Sun.

3. No comet has even been known to cause a CME.

4. Comets do not cause Earthquakes (unless they collide with the Earth).

-- Kevin Heider

Kevin Heider said...

sky guy, C/2011 W3 (Lovejoy) passed 0.00555 AU from the Sun (less than half the distance of C/2012 S1 @ 0.012 AU).

Lynn Umby said...

If you run the simulations, you'll see how incredibly close this comet will get to Mars early Oct 2013. Maybe even close enough to be peturbed. Might be a photo op for MRO or Curiosity.

Wanzewurld said...

What are the objects showing up as dotted lines bottom left, upper right, and center right? Just curious.

Ademir Xavier said...

Thank you for the information. You all are doing a wonderful job!

Rachel Rotz said...

How large is the comet? Scientists should know this based on orbit calculations.

Anonymous said...

Question about the data figures: Is the period listed in years? If so, how far out from the sun is the orbit at maximum distance from the sun? Seems like a huge orbit.


Kevin Heider said...


Whether the comet is 3km or 30km in diameter, it is basically a massless particle in comparison to the planets and Sun. The comet would have to perturb a small body to measure its small mass. Due to the coma surrounding the comet, it is difficult to directly estimate the size of the central nucleus.

Kevin Heider said...


It is still a little early to hope to accurately estimate the orbital period of the comet. The incoming orbit could have been tens or hundreds of thousands of years depending on the exact eccentricity value. It requires much less accuracy to calculate where the comet will be in 1 year than where it was or will be in 10,000+ years.

Do keep in mind that the incoming orbital period will be different than the outgoing orbital period due to perturbations by the planets and Sun.

-- Kevin Heider

Anonymous said...

Any opinions on whether this comets tail will be the source for future meteor showers?


Anonymous said...

Where do we have to look exactly for seeing the comet?

NickAstronomer said...

Thanks Kevin for your replies... to see the comet, go to the minor planet centre website (or indeed and select it from the list of comets for your area. As for the tail being a source for meteor showers, it is possible yes

Kevin Heider said...

There is speculation that there could be a meteor shower around January 15-16th. But the orbit should be better refined and the long-term activity level of the comet better determined.

Chris Garvey said...

Anonymous said...
Where do we have to look exactly for seeing the comet?
See thee table just before the comments.

Anonymous said...

Anyone think we will get a meteor shower associated with this comet when we pass through the C/2012 S1 debris trail on Jan 16th, 2014.

According to the current orbit we will pass through the area that was the comets tail around this date.

Also isn't its current orbit going to bring it very very close to Mars around October 1st 2013.

The next 6 months will be interesting to see if its refined orbit brings it even closer to Mars. The Mars rover can image what may possibly be the brightest comet in modern history from another planet. Awesome!

Kevin Heider said...

As of 2 October 2012, the orbit of ISON (largely thanks to precovery images in Dec 2011 and Jan 2012) is already determined well enough to know that the comet will safely pass somewhere from 0.0712AU to 0.0743AU of Mars. So it will miss Mars by at least 10,650,000 km (6,620,000 mi).

Voyager2 said...

why we don't know yet the size of the comet?

glcat said...

Just heard today it will be really close to mars and this should verify the electrical connection the sun has with the planets. should be quite a show. I thought 0.4 au is damn close. That is the projected earth fly by.

Anonymous said...

will this comet pass thru the astroid belt and if so what are the chances of collitions

Anura Guruge said...

I am confused why 'ISON' is listed as the discoverer. Was it because Vitali Nevski first reported it as a Minor Planet and posted it on NEOCP? Or was it because you good folks helped out? Thank you. Keep up the good work. Cheers, Anura

keyem said...

Actually is the e < 1 or not?

Anura Guruge said...

To "Keyem" who asked whether 'e' is <1. Not as yet! Slightly above 1 right now. BUT, astronomers believe that, based on at least one other recent observation, that 'e' could, most likely will, drop below 1 on the return once it has passed the gas giants. Basically the theory is that the 'e' of comets such as C/2012 S1 changes depending on their distance from the Sun. Hope that helps.
Anura Guruge

Anura Guruge said...

To Ernesto and his team,
Can I just give folks a heads up that I just published a 50,000+ word (100+ pages) Kindle eBook on: 'Comet ISON, C/2012 S1 (ISON), The Great Comet of 2013'. I sent a 'copy' to Ernesto electronically via Amazon. It is available on all Amazon stores worldwide. I priced it at U.S. $3.99! Get it 39.9 million miles. There is a 'Look Inside' feature.
Thanks. Cheers, Anura Guruge