Splitting event in comet 168P/Hergenrother

Over the past few weeks, comet 168P/Hergenrother has been under intense scrutiny due to its strange behaviour, namely a 6 magnitude surge in its brightness in a matter  of several nights. Simultaneously the central condensation became markedly brighter and  sharper, whilst the coma was also seen to grow in size. This has triggered the attention of amateur and professional astronomers alike. Most of the time these brightening events (comets are among the most  unpredictable astronomical objects from themselves) originate from some activity within, or associated with, the nucleus of the  comet. There were strong assumptions in the astronomical community on the possible emergence of some visible fragments in the coma, the potential consequences of a break-up of in the comet's nucleus.

There have even been a few claims relating to a sighting within the comet hunting community, however these turned out to be most likely false alarms, due to the unfavourable combination of seeing/instrumental  resolution within the amateur community. Our team have been monitoring the evolution of this comet with a variety of  instruments including the research grade Faulkes Telescopes, with sub arcsecond imaging capability.

Today...we found the fragment...

Our team performed follow-up observations of comet 168P/Hergenrother on 2012, Oct. 26.4, remotely through the Faulkes Telescope North (Haleakala) under good seeing conditions, and a scale of 0.3"/px.

Stacking of 13 R-filtered exposures, 30-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North on 2012, Oct. 26.4, through a 2.0-m f/10.0 Ritchey-Chretien + CCD, under good seeing conditions, shows the presence of a secondary nucleus, or fragment, placed about 2" in PA 188 with respect to the main central condensation of comet 168P.

The magnitude of this fragment was measured to be R about 17, and it shows a diffuse coma nearly 2" in diameter. Click on the image below for a bigger version.

Below you can see an animation obtained by means of the same frames (here East is to the left, North is to the bottom). The animation covers about 20 minutes in total. Click on the thumbnail for a bigger version.

Below you can find the astrometry lines (0168P: main nucleus of comet Hergenrother, 168Pb the new fragment we discovered today):

0168P        KC2012 10 26.42126 23 41 31.60 +34 07 36.5          15.6 N      F65
0168P        KC2012 10 26.42747 23 41 31.37 +34 07 44.6          14.3 N      F65
0168P        KC2012 10 26.42901 23 41 31.31 +34 07 46.6          15.7 N      F65
     168Pb   KC2012 10 26.42126 23 41 31.57 +34 07 34.5          17.2 R      F65
     168Pb   KC2012 10 26.42747 23 41 31.32 +34 07 42.3          16.9 R      F65
     168Pb   KC2012 10 26.42901 23 41 31.28 +34 07 44.3          17.4 R      F65

There was no evidence of this fragment in our previus follow-up images, obtained through the Faulkes Telescopes 2.0-m f/10.0 Ritchey-Chretien + CCD on 2012, Oct. 22.4 and Oct. 3.6, to limiting magnitude about 19.. See our previous post about comet 168P here and here.

UPDATE - September 30, 2014

Paper by Z. Sekanina (JPL) about comet 168P fragmentation has been published on Arxiv with acknowledgement to our discovery and mention to this blog:

To read and download the full paper: http://arxiv.org/abs/1409.7641

by Giovanni Sostero, Nick Howes & Ernesto Guido

New Comet: C/2012 U1 (PANSTARRS)

Cbet nr. 3264, issued on 2012, October 22, announces the discovery of a new comet (discovery magnitude 21.0) by Pan-STARRS Survey on images obtained with the 1.8-m Pan-STARRS1 telescope at Haleakala  on October 18.3. The new comet has been designated C/2012 U1 (PANSTARRS).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 5 R-filtered exposures, 120-sec each,obtained remotely, from Haleakala-Faulkes Telescope North on 2012, Oct. 22.45, through a 2.0-m f/10.0 Ritchey-Chretien + CCD under good seeing conditions, shows that this object is a comet: diffuse coma nearly 5" in diameter.

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

  

M.P.E.C. 2012-U66 (including prediscovery Mount Lemmon Survey observations from Oct. 17.4) assigns the following preliminary parabolic orbital elements to comet C/2012 U1: T 2014 June 30.96; e= 1.0; Peri. = 58.03; q = 6.31 AU; Incl.= 66.73.

by Ernesto Guido, Nick Howes, Alison Tripp & Giovanni Sostero

Update on Comet 168P/Hergenrother

Our team performed follow-up observations of comet 168P/Hergenrother on 2012, Oct. 22.4, remotely through the 2m, f/10 Ritchey-Chretien + CCD of Faulkes Telescope North (Haleakala) under good seeing conditions, and a scale of 0.3"/px. Comet 168P has recently undergone an outburst with its magnitude increasing from ~14-15 to magnituide ~9.5. For more info about the recent outburst of this comet, see our previous post here.

Recent observations posted on comet-images ml were showing a "cloud" of material trailing the nucleus in the anti-solar direction. In our image (stacking of 9 x 30-second exposures) is visible an unresolved and diffuse trail about 6" long and 3" wide in PA145. Click on the image for a bigger version.

Below you can see a graph showing recent magnitude estimates of comet 168P.  Click on the image for a bigger version.

Credit: Seiichi Yoshida

by Giovanni Sostero, Nick Howes, Alison Tripp & Ernesto Guido

New Comet: P/2012 T7 (VOROBJOV)

Cbet nr. 3260, issued on 2012, October 18, announces the discovery of a new comet (discovery magnitude 20.1) by Tomas Vorobjov on three 120-s images that he took on October 15 remotely with Alexander Kostin (Houston, TX, U.S.A.) using a 0.81-m f/7 Ritchey-Chretien reflector located at the Mt. Lemmon SkyCenter via the Sierra Stars Observatory Network. The new comet has been designated P/2012 T7 (VOROBJOV).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 3 R-filtered exposures, 120-sec each,obtained remotely,from Haleakala-Faulkes Telescope North on 2012, Oct. 18.43, through a 2.0-m f/10.0 Ritchey-Chretien + CCD under good seeing conditions, shows that this object is a comet: narrow tail nearly 15" long in PA 270 elongated coma 6"x4" in the same direction
 

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

M.P.E.C. 2012-U40 assigns the following preliminary elliptical orbital elements to comet P/2012 T7: T 2012 June 16.58; e= 0.33; Peri. = 174.76; q = 3.78 AU; Incl.= 13.55.

by Nick Howes, Giovanni Sostero & Ernesto Guido.

New Comet: C/2012 T6 (KOWALSKI)

Cbet nr. 3259, issued on 2012, October 18, announces the discovery of a new comet (discovery magnitude 17.6) by R. A. Kowalski on Catalina Sky Survey images obtained with the 0.68-m Schmidt telescope on October 15.4. The new comet has been designated C/2012 T6 (KOWALSKI).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 7 R-filtered exposures, 30-sec each, obtained remotely,from the Siding Spring-Faulkes Telescope South on 2012, Oct. 16.63, through a 2.0-m f/10.0 Ritchey-Chretien + CCD under good seeing conditions,shows that this object is a comet: narrow tail nearly 13" long in PA 290 and a wide, fan-shaped tail about 20" long toward the North-northwest sharp coma about 7" in diameter.

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

M.P.E.C. 2012-U39 assigns the following preliminary parabolic orbital elements to comet C/2012 T6: T 2012 Aug. 25.08; e= 1.0; Peri. = 196.47; q = 1.79 AU; Incl.= 34.28.

by Ernesto Guido, Alison Tripp, Giovanni Sostero & Nick Howes

New Comet: C/2012 T5 (BRESSI)

Cbet nr. 3258, issued on 2012, October 18, announces the discovery of a new comet (discovery magnitude 18.6) by T. H. Bressi on CCD mosaic images taken with the Spacewatch 0.9-m f/3 reflector at Kitt Peak on October 14.4. The new comet has been designated C/2012 T5 (BRESSI).

According to its preliminary parabolic orbital, comet C/2012 T5 (BRESSI) has it perihelion on T 2013 Feb. 23 with q = 0.31 and it might reach the peak  magnitude ~8. (graph generated using the software Orbitas - click on the image for a bigger version).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 7 R-filtered exposures, 120-sec each,obtained remotely,from H06 (ITelescope network near Mayhill, NM) on 2012, Oct. 18.33, through a 0.43-m f/6.8 astrograph + CCD + f/4.5 focal reducer shows that this object is a comet: compact coma about 5" in diameter and tail nearly 12" long in PA 270.

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

 
M.P.E.C. 2012-U38 assigns the following preliminary parabolic orbital elements to comet C/2012 T5: T 2013 Feb. 23.55; e= 1.0; Peri. = 318.27; q = 0.32 AU; Incl.= 71.87.

by Giovanni Sostero, Nick Howes & Ernesto Guido

New Comet: P/2012 T1 (PANSTARRS)

Cbet nr. 3252, issued on 2012, October 11, announces the discovery of a new comet (discovery magnitude 20.7) by Pan-STARRS survey on CCD images obtained  with the 1.8-m Ritchey-Chretien + CCD on October 06. Prediscovery Pan-STARRS observations from 2011 July 28 were identified by G. V. Williams. The new comet has been designated P/2012 T1 (PANSTARRS).

After posting on the Minor Planet Center's NEOCP webpage, other CCD astrometrists have also commented on the object's cometary appearance. We performed some follow-up measurements of this object on 2012, October 11.63. Stacking of 8 R-filtered exposures, 60-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North through a 2.0-m f/10.0 Ritchey-Chretien + CCD, shows that this object is a comet with a faint coma nearly 5" in diameter.

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

M.P.E.C. 2012-T55 assigns the following elliptical orbital elements to comet P/2012 T1: T 2012 Nov. 21.89; e= 0.20; Peri. = 323.21; q = 2.41 AU; Incl.= 11.4. According to his orbital characteristics of asteroids (with a Tisserand parameter T_jup = 3.176 ) and the physical characteristics of comets this object seems to be a new member of Main Belt Comets (MBCs). (see also our previous post about 596 Scheila)

Below is shown the distribution of the mass-losing asteroids, including their relation to the asteroids (orange dots) and classical comets (blue dots). In this graph the position of newly discovered P/2012 T1 (PANSTARRS) is just nearby 300163 (2006 VW139). Click on the image for a bigger version.

Credit: David Jewitt

by Ernesto Guido, Robert Shirley, Nick Howes & Giovanni Sostero