New Comet: C/2013 B2 (CATALINA)

Cbet nr. 3390, issued on 2013, January 23, announces the discovery of a new comet (discovery magnitude 18.9) on images taken by J. A. Johnson with the Catalina Sky Survey's 0.68-m Schmidt telescope + CCD on January 16.2. The new comet has been designated C/2013 B2 (CATALINA). The apparently asteroidal object posted on the Minor Planet Center's NEOCP webpage, has been found to show cometary appearance by CCD astrometrists elsewhere.

We performed follow-up measurements of this object, while it was still on the neocp. Stacking of 22 R-filtered exposures, 50-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North on 2013, Jan. 23.5, through a 2.0-m f/10.0 Ritchey-Chretien + CCD, shows that this object appears slightly diffuse compared to the nearby field stars of similar brightness and elongated toward PA 220.

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

M.P.E.C. 2013-B84 assigns the following preliminary parabolic orbital elements to comet C/2013 B2: T 2013 June 30.59; e= 1.0; Peri. = 156.14; q = 3.75;  Incl.= 43.56.

Images of  C/2013 B2 (CATALINA) taken in collaboration with the Faulkes Project and :

Shoeburyness High School - Philip Benson
South Hampstead High School - Chris Everall

by Nick Howes, Ernesto Guido & Alison Tripp

New Comet: P/2013 A2 (SCOTTI)

Cbet nr. 3376, issued on 2013, January 08, announces the discovery of a new comet (discovery magnitude 19.5) by J. Scotti with the 691 Steward Observatory, Kitt Peak, on images obtained with the 0.9-m f/3 reflector + CCD on January 06.2. The new comet has been designated P/2013 A2 (SCOTTI).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 6 R-filtered exposures, 60-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North on 2013, Jan. 08.6, through a 2.0-m f/10.0 Ritchey-Chretien + CCD, shows that this object appears "soft" compared to the nearby field stars of similar brightness and elongated toward PA 290. Our observations combined with those of Peter Phelps of Hazelmere School in the UK, using Faulkes South later in the day helped confirm the nature of the object.

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

M.P.E.C. 2013-A45 assigns the following preliminary elliptical orbital elements to comet P/2013 A2: T 2013 May  16.14; e= 0.57; Peri. = 182.74; q = 1.98 AU;  Incl.= 3.89.

Our confirmation image of comet P/2013 A2 (SCOTTI) was featured on BBC StarGazing Live on January 10, 2013. 

by Nick Howes & Ernesto Guido

Comets C/2012 K5 (LINEAR) & C/2012 F6 (Lemmon)

C/2012 K5 (LINEAR) & C/2012 F6 (Lemmon) are the brightest comets currently visible in the sky (together with comet C/2011 L4 PanSTARRS which is unobservable in Northern Hemisphere until 2013 March while is observable very low in the sky in the Southern Hemisphere until mid February).

C/2012 K5 (LINEAR) was discovered by the LINEAR survey on CCD images taken with the 1.0-m f/2.15 reflector on May 25.3. For more info about the discovery of this comet see our previous post here. Latest visual estimates indicate a total visual brightness of about m1 ~ 8.5. This comet is very close to the Earth now (~0.369 AU, while it is at ~1.3 AU from the Sun). The visibility condition is good in the Northern Hemisphere. But after mid January, the comet moves away from the earth and fade out rapidly. It will become observable in good condition also in the Southern Hemisphere after January.

Below you can see a graph generated using the software Orbitas and showing the C/2012 K5 predicted magnitude (in red) versus the maximum height (for Northern Hemisphere). Click on the image for a bigger version.

C/2012 K5 (LINEAR)  - Faulkes Telescope South - January 07, 2013 (North is up, East to the left)

C/2012 K5 (LINEAR)  MCM (Median Coma Model) 

The MCM filter creates an artificial coma, based on the photometry of the original image, and subtract the original image itself in order to highlight the internal zones of different brightness that are very close to the inner core and that would normally be hidden from the diffuse glow of the comet.

C/2012 K5 (LINEAR)  RWM (Radial Weighted Model) 

RWM - 1/r theoretical coma subtraction.

Below you can see an animation of comet C/2012 K5 obtained using the same frames of the images above. Click on the thumbnail for a bigger version:

C/2012 F6 (Lemmon) was discovered by the Mount Lemmon Survey on CCD images taken with the 1.5-m reflector on March 23, 2012. Latest visual estimates indicate a total visual brightness of about m1 ~ 8.0. This comet is getting brighter much faster than expected. Perihelion is on March 24 at 0.73AU in 2013 March. If this trend continues it may brighten up to magnitude ~3. In the Northern Hemisphere, it is only observable until early January and then after middle May 2013 while in the Southern Hemisphere, it keeps observable while brightening gradually after this in good condition.

Below you can see a graph generated using the software Orbitas and showing the C/2012 F6 predicted magnitude (in red) versus the maximum height (for Northern Hemisphere). Click on the image for a bigger version. (Please consider that as explained above, the comet is surprisingly bright and over 4 magnitudes brighter than the ephemeris)

 C/2012 F6 (Lemmon) - Faulkes Telescope South - January 07, 2013 (North is up, East to the left)

C/2012 F6 (Lemmon) -  MCM (Median Coma Model)  

C/2012 F6 (Lemmon) - RWM (Radial Weighted Model)

Below you can see an animation of comet C/2012 F6 obtained using the same frames of the images above. Click on the thumbnail for a bigger version:

Images of  C/2012 K5 & C/2012 F6 taken in collaboration with the Faulkes Project and :

Longley Park Sixth Form College  - Ismail Musa
Glenlola Collegiate   -  Jacquie Milligan
Bury College   -  Dr. Lyshia Quinn

by Ernesto Guido, Nick Howes & Martino Nicolini

New Comet: C/2012 Y3 (MCNAUGHT)

Cbet nr. 3367, issued on 2013, January 01, announces the discovery of a new comet (discovery magnitude 15.2) by the E12 Siding Spring Survey on images obtained with the 0.5-m Uppsala Schmidt + CCD on December 30.6. The new comet has been designated C/2012 Y3 (MCNAUGHT).

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 19 unfiltered exposures, 30-sec each,obtained remotely,from Q62 (iTelescope Observatory, Siding Spring) on 2013, Jan. 01.46, through a 0.32-m f/9.0 Ritchey-Chretien + CCD shows that this object is a comet: coma about 10" in diameter with a fan-shaped tail elongated in PA 85.

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

M.P.E.C. 2013-A03 assigns the following preliminary parabolic orbital elements to comet C/2012 Y3: T 2012 Aug. 26.59; e= 1.0; Peri. = 236.15; q = 1.78 AU; Incl.= 73.90.

by Ernesto Guido & Nick Howes

Recovery of comet 26P/Grigg–Skjellerup

MPEC 2012-Y30, issued 2012 December 26, reports our recovery of comet 26P/Grigg–Skjellerup. We found the comet on 2012 December 05.6 and December 14.5 at about magnitude 20. We imaged it remotely with the 2.0-m f/10 from the Siding Spring-Faulkes Telescope South.

This comet is named after the singing teacher and amateur astronomer John Grigg and after J. Frank Skjellerup, an Australian telegraphist working at the Cape of Good Hope in South Africa. On July 10, 1992, comet 26P was visited by Giotto spacecraft after its successful close encounter with comet Halley. The Giotto camera has been damaged in the Halley flyby and there are no pictures of the nucleus. In 1972 the comet was discovered to produce a meteor shower (first predicted by Harold Ridley), the Pi Puppids, and its current orbit makes them peak around April 23, for observers in the southern hemisphere, best seen when the comet is near perihelion. 

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

While below you can see an animation showing the movement of the comet (7 frames x 30 seconds each). North is up, East is to the left (click on the thumbnail below for a bigger version):

Comet 26P/Grigg–Skjellerup was last observed (before our recovery) on August 09, 2008 by mpc code 204 (Schiaparelli Observatory). While there is also a single night observation by F51 – Pan-STARRS 1,  Haleakala dated November 25, 2011, a comet recovery requires 2 nights of observations, "as it is not possible to unambiguously identify a comet by  position and rate alone without a second night of data to verify the orbit." (Hainaut et al. A&A 1997).

by Nick Howes & Ernesto Guido

Asteroid (99942) Apophis

Asteroid (99942) Apophis was discovered on 2004 June 19 by R. A. Tucker, D. J. Tholen and F. Bernardi at Kitt Peak and then lost until it was serendipitously recovered in December of 2004. This Aten class asteroid, approximately 270 meters in diameter, caused a brief period of concern in December 2004 because initial observations indicated a small probability that it would strike the Earth in 2029. Thanks to additional observations, the 2029 threat was eventually ruled out. However, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through a gravitational  keyhole, a precise region in space no more than about a 600 meters wide, that would set up a future impact on 2036. The principal source of uncertainty is the acceleration due to the Yarkovsky effect, a non-gravitational effect that is a function of the asteroid's rotation period, pole direction, thermal properties, mass, shape, and dimensions. So this asteroid continues to receive considerable attention from amateur and professional astronomers.  

Apophis became (on 2004) the first object rated level 2 on the Torino scale, and for only a short time it was subsequently upgraded to level 4, the record for highest Torino rating. Currently Apophis has been downgraded to 0 in the Torino scale (the currently  highest-scaled objects are 2007 VK184 & 2011 AG5 at level 1).

The following citation is from MPC 54567: "(99942) Apophis = 2004 MN4. Also known as Apep, the Destroyer, Apophis is the Egyptian god of evil and destruction who dwelled  in eternal darkness.  As a  result of its passage within 40 000 km of the earth on 2029 Apr. 13, this minor planet will move from the Aten to the Apollo  class."

Apophis will make a very close Earth approach on April 13, 2029 at 2146UT when it will pass within 0.1 LD (Lunar Distances = ~384,000 kilometers)  or 0.00025 AU (1 AU = ~150 million kilometers). This will be the closest approach by something this large currently known. During the 2029 approach, Apophis' brightness will peak at magnitude 3.3, so it will be visible to the naked eye.

Before the 2029 encounter, Apophis will have a close approach with our planet on January 2013.  Actually, (99942) Apophis will have a close approach with Earth at about 37.6 LD (Lunar Distances = ~384,000 kilometers) or 0.0967 AU (1 AU = ~150 million kilometers) at 1143 UT on Jan. 09, 2013. On that date, the asteroid will reach the magnitude ~15.8 while moving at ~ 3.49"/min. According to Giorgini et al. (2008), it's likely that radar astrometry in 2013 will shrink the uncertainties sufficiently to completely rule out an impact in the 2030s.

We performed some follow-up measurements of this object just few weeks before its 2013 close approach, from the H06 ITelescope network (near Mayhill, NM) on  2012, Dec. 13.4, through a 0.25-m f/3.4 reflector + CCD. Below you can see our image, 19x30-second exposures, taken with the asteroid at magnitude ~17.5 and moving at ~2.57"/min. Click on the image below to see a bigger version. North is up, East is to the left.

Below you can see a short animation showing the movement of (99942) Apophis (each frame is a stack of 19x30-second exposures). North is up, East is to the left. Click on the thumbnail for a bigger version:

UPDATE - January 11, 2013

ESA’s Herschel space observatory made new observations of asteroid Apophis as it approached Earth this weekend. The data shows the asteroid to be bigger than first estimated, and less reflective. "Herschel provided the first thermal infrared observations of Apophis at different wavelengths, which together with optical measurements helped refine estimates of the asteroid’s properties. Previous estimates bracketed the asteroid’s average diameter at 270 ± 60 m; the new Herschel observations returned a more precise diameter of 325 ± 15 m".  The image below shows the asteroid in Herschel’s three PACS wavelengths: 70, 100 and 160 microns, respectively (click on it for a bigger version). For more info about Herschel's find click here.

Credit: ESA/Herschel/PACS/MACH-11/MPE/B.Altieri (ESAC) and C. Kiss (Konkoly Observatory)

After tracking asteroid 99942 Apophis with NASA's Goldstone radar dish, astronomers are now certain that the threatening asteroid has essentially no chance of striking Earth in 2036. See S&T article here for more details.

by Ernesto Guido & Nick Howes

Close Approach of Asteroid (4179) Toutatis

4179 Toutatis was discovered by C. Pollas at Caussols (France) on January 4, 1989. 4179 Toutatis was first sighted on February 10, 1934, as object 1934 CT, and then promptly lost. It remained a lost asteroid for several decades until it  was discovered by Pollas.

According to Minor Planet Circ. 16444: "Named after the Gaulish god, protector of the tribe. This totemic deity is well known because of the cartoon series "Les aventures d'Asterix" by Uderzo and Goscinny. This tells the stories of two almost fearless heroes living in the last village under siege in Roman-occupied Gaul in 50 B.C., and whose only fear is that the sky may fall onto their heads one day. Since this object is the Apollo object with the smallest inclination known, it is a good candidate to fall on our heads one of these days... But as the chief of the village always says: "C'est pas demain la veille..." Citation written by the discoverer and A. Maury and endorsed by J. D. Mulholland, who with Maury obtained the discovery plates."

4179 Toutatis is a highly irregular body consisting of two distinct "lobes", with maximum widths of about 4.5 km and 2.4 km respectively (4.5 × 2.4 × 1.9 km; absolute magnitude H=15.3) and it had a close approach with Earth at about 18 LD (Lunar Distances = ~384,000 kilometers) or 0.0463 AU (1 AU = ~150 million kilometers) at 0640 UT on Dec. 12, 2012. Its magnitude will be between 10.5 to 11 from December 11 through December 23, 2012.

Moreover, Toutatis will be the target of a flyby by the Chinese Chang'e 2 spacecraft on December 13, 2012   Chang'e 2 was originally launched to study the Moon but was diverted in April, 2012 for the asteroid encounter.

We performed some follow-up measurements of this object just few hours before its 2012 close approach, from the I89 iTelescope network (Nerpio, Spain) on  2012, Dec. 11.9, through a 0.15-m f/7.3 refractor + CCD. Below you can see our image, single 120-second exposure, taken with the asteroid at magnitude ~10.5 and moving at ~20.7"/min. The asteroid is trailed in the image due to its fast speed. At the moment of the close approach 4179 Toutatis will move at ~ 21.86"/min. Click on the image below to see a bigger version. North is up, East is to the left.

Below you can see a short animation showing the movement of 4179 Toutatis (40 consecutive 10-second exposures). East is up, North is to the right. Click on the thumbnail for a bigger version:

Toutatis passes by Earth’s orbit roughly every 4 years. Four years ago it didn’t come quite so close (0.0502 AU). But four years before that (in September 2004) it missed us by just 0.0104 a.u., less than a quarter of its distance this time. The next notable close approach of Toutatis will be November 5, 2069, when the asteroid will fly by at a distance of only 0.0198 AU (7.7 lunar distances). See graphs below (click on it for bigger versions).

Credit: Hazards Due to Comets & Asteroids by T. Gehrels - University of Arizon Press

Credit: Hazards Due to Comets & Asteroids by T. Gehrels - University of Arizon Press

Thanks to its proximity and size Toutatis was a strong target for radar imaging. Astronomers of NASA's Goldstone radar were tracking the asteroid as it passes by Earth and they obtained images of unprecedented clarity. Click on the image below for a bigger version.

2012 Goldstone Radar Observations of (4179) Toutatis

According to  radar team member Michael Busch: "Toutatis appears to have a complicated internal structure. Our radar measurements are consistent with the asteroid's little lobe being ~15% denser than the big lobe; and they indicate 20% to 30% over-dense cores inside the two lobes.". This raises the interesting possibility that asteroid Toutatis is actually a mash up of smaller space rocks.  "Toutatis could be re-accumulated debris from an asteroid-asteroid collision in the main belt," he says.

UPDATE - December 18, 2012

The Chinese Chang'e 2 spacecraft has successfully imaged Toutatis during his flyby on December 13, 2012. See image below captured at 93–240 km distance between 16:30:09–16:30:24, maximum resolution 10 meters/pixel. Click on the image for a bigger version.

by Ernesto Guido & Nick Howes