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

Wednesday, September 12, 2012

New update on comet C/2011 L4 (PANSTARRS)

Comet C/2011 L4 (PANSTARRS), discovered by Pan-STARRS 1 telescope on Haleakala, Maui, on the night of 2011, June 5-6, will reach perihelion in March 2013 when it will be located only 0.30 AU from the Sun and might become a bright naked eye object ( with a peak magnitude of anywhere from +1 to -1). At its brightest C/2011 L4 will appear only 15° from the Sun.

The comet is now at 3.2 AU from the Sun (m2 ~ 14.0). While visually C/2011 L4 is at m1 ~ 11.

We performed some follow-up measurements of comet C/2011 L4 remotely from the Siding Spring-Faulkes Telescope South on 2012, September 10.4 through a 2.0-m f/10.0 Ritchey-Chretien + CCD. Below you can see our follow-up image (click on it for a bigger version):


Below you can see the lightcurve of comet C/2011 L4 (PANSTARRS) collected by Seiichi Yoshida on his comet webpage: 

                                  (Credit: Seiichi Yoshida)

As a comparison, below you can see our image of the comet taken on June 7.4, 2011 just one day after his discovery by Pan-STARRS Survey. The comet was then at 8.2 AU from the Sun (m2 ~ 19.5).



While below there is our image taken on May 18.6, 2012 with the comet at 4.6 AU from the Sun (m2 ~ 15.6).


Here you can read our full past reports about this comet:

http://remanzacco.blogspot.it/2011/06/new-comet-c2011-l4-panstarrs.html

http://remanzacco.blogspot.it/2012/05/update-on-comet-c2011-l4-panstarrs.html


by Ernesto Guido, Kris Rochowicz, Nick Howes & Giovanni Sostero

Tuesday, September 11, 2012

Another Fireball Flash on Jupiter?

On September 10, Dan Petersen of Racine, Wisconsin, reported on Cloudy Nights forum the visual detection of a flash on Jupiter at 11:35 UT (of September 10 2012):

"This morning (9/10/2012) at 11:35:30 UT, I observed a bright white two second long explosion just inside Jupiter's eastern limb, located at about Longitude 1 = 335, and Latitude = + 12 degrees north, inside the southern edge of the NEB. I used my Meade 12" LX200 GPS telescope and a binoviewer working at 400X for the observation, seeing was very good at the time."

Another amateur astronomer, George Hall of Dallas, Texas, was video-recording Jupiter at the time, and he confirmed the fireball. The video was captured with a 12" LX200GPS, 3x Televue Barlow, and Point Grey Flea 3 camera. Click on the image below for a bigger version.

                                     (Credit: George Hall)

Hall also posted online a short clip of the impact video. 

It is possible that the flash was caused by a meteor or small asteroid/comet hitting Jupiter. This is the sixth time that we have seen something slam into Jupiter, beginning with a fireball recorded by Voyager 1 as it flew past in 1979 and the famous impact of Comet Shoemaker-Levy 9 in 1994. The more recent cases are that of July 19, 2009 (discovered by Anthony Wesley), of June 03, 2010 (discovered by Anthony Wesley and Christopher Go) and of August 20, 2010 (discovered by Masayuki Tachikawa & Aoki Kazuo).

The role of planet Jupiter as a shield protecting Earth from getting hit by such objects is still controversial and it has been discussed in depth in a series of articles by Jonathan Horner and Barrie Jones (Jupiter - friend or foe?):

"It has long been assumed that the giant planet Jupiter acts as a shield, significantly lowering the impact rate on the Earth from both cometary and asteroidal bodies. Such shielding, it is claimed, enabled the development and evolution of life in a collisional environment which is not overly hostile. The reduced frequency of impacts, and of related mass extinctions, would have allowed life the time to thrive, where it would otherwise have been suppressed. However, in the past, little work has been carried out to examine the validity of this idea. Our results show that the situation is far less clear cut that has previously been assumed - for example, the presence of a giant planet can act to enhance the impact rate of asteroids on the Earth significantly."

In this blog we reported about the 2009 & 2010 impact flashes on Jupiter:




Once again amateur astronomers have shown their ability in monitoring almost permanently the planet Jupiter.

For other info about this 2012 event please see also:

http://www.skyandtelescope.com/observing/home/Another-Flash-on-Jupiter-169263686.html

http://cosmicdiary.org/fmarchis/2012/09/10/another-fireball-on-jupiter/


UPDATE - September 14, 2012

On September 11, 2012 Astronomer Mike Wong was able to analyze the video data of the flash kindly provided by George Hall. According to his analysis he made the prediction that "this event is too small to create a visible impact scar".

Several observers have imaged the planet Jupiter on the second and third rotations after the fireball and nothing new has been detected at the impact site. So the total energy seems to have been low and "we can conclude that the flash was most likely a meteor due to a small (diameter < 10m assuming a density of 2 g/cc) meteoroid".

by Ernesto Guido

Monday, September 10, 2012

Close Approach of Asteroid 2012 QC8

M.P.E.C. 2012-Q25, issued on 2012 Aug. 20, reports the discovery of the asteroid 2012 QC8 (discovery magnitude 17.1) by Siding Spring Survey on images taken on August 19.6 with a 0.5-m Uppsala Schmidt + CCD.

2012 QC8 has an estimated size of 670 m - 1.5 km (H=18.0) and it will have a close approach with Earth at about 22.7 LD (Lunar Distances) or 0.0583 AU at 2256 UT on 14 Sept. 2012. This asteroid will reach an average magnitude of 14.6 around September 10-13. 2012 QC8 is a current radar target for ground based radio telescopes.
 
We performed some follow-up measurements of this object, remotely from the Siding Spring-Faulkes Telescope South on 2012, September 10.4, through a 2.0-m  f/10.0 Ritchey-Chretien + CCD. Below you can see our image, stack of 5x5-second exposures, taken with the asteroid at magnitude ~14.6 and moving at 16.15"/min. At the moment of the close approach on 14 September, 2012 QC8 will move at ~ 29"/min.


Below you can see a short animation showing the movement of 2012 QC8 (each frame is a 5-second exposure). Click on the thumbnail for a bigger version:



by Ernesto Guido, Kris Rochowicz, Nick Howes & Giovanni Sostero

Tuesday, September 4, 2012

Close Approach of PHA Asteroid 2012 QG42

M.P.E.C. 2012-Q72, issued on 2012 Aug. 28, reports the discovery of the PHA asteroid 2012 QG42 (discovery magnitude 16.8) by Catalina Sky Survey on images taken on August 26.3 with a 0.68-m Schmidt + CCD. 

2012 QG42 has an estimated size of 200 m - 500 m (H=20.4) and it will have a close approach with Earth at about 7.43 LD (Lunar Distances) or 0.019 AU at 0510 UT on 14 Sept. 2012. This asteroid will reach an average magnitude of 13.6 around September 10-12. 2012 QG42 is a current radar target for ground based radio telescopes. Astronomers at Goldstone and Arecibo will try to observe it on September as "this object should be a really strong delay-Doppler imaging target".

It was classified as a PHA ((Potentially Hazardous Asteroid). PHA are asteroids larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time. 

We performed some follow-up measurements of this object, remotely from the Siding Spring-Faulkes Telescope South on 2012, September 04.5, through a 2.0-m  f/10.0 Ritchey-Chretien + CCD. Below you can see our image, stack of 4x10-second exposures, taken with the asteroid at magnitude ~15.2 and moving at 4.35"/min. At the moment of the close approach on 14 September, 2012 QG42 will move at ~ 49"/min.



Below you can see a short animation showing the movement of 2012 QG42 (each frame is a 10-second exposure). Click on the thumbnail for a bigger version:



UPDATE - September 14, 2012

On mpml mailing list, Brian Warner presented the first lightcurve obtained using data provided by different amateur astronomers all around the world:

"Critter is still observable but the phase angle is now around 70° whereas most  of the data are from < 20°. The amplitude and shape of the curve may be evolving  and so it becomes more and more difficult to merge all the data into a single  set. Ideally, a data set taken over the next 24 hours from stations widely-separated in longitude would be treated as "stand alone" and would help  with modeling - LOTS!"

Below you can see the plot of the current photometry for 2012 QG42. It reveals this PHA rotates once every 24.278 hours, or 24 hours, 16 minutes, 40.8 seconds. (click on the image for a bigger version).


                                    (Credit: Brian Warner)

In the meantime the radar team announced on mpml mailing list that radar echoes from 2012 QG42 have been successfully  detected at Goldstone on September 13:

"We spent most of our time during the track improving the orbit by estimating Doppler and ranging corrections to the ephemerides. The radar data are  consistent with a slow rotation period as inferred from the lightcurves  reported by Brian Warner. We have one more track scheduled at Goldstone on Sep. 15 and four tracks at Arecibo on Sep. 14-17."

by Ernesto Guido, Nick Howes & Giovanni Sostero