67P/Churyumov-Gerasimenko

67P/Churyumov-Gerasimenko was discovered by Klim Churymov en photographs of 32P/Comas Solá taken by Svetlana Gerasimenko on October 22nd 1969. Churyumov was measuring the positions of Comet Comas Sola and discovered to his surprise that in one the image that he was measuring it was 2 degrees out of position. On investigating he realised that the object that he had thought was Comas Solá was, in fact, a new comet. He soon found a second image of this new comet on a plate taken on September 9th. Other images were found at Nice and in the USA on September 13th and 14th photographs. The comet was already receding from perihelion and fading.

The comet has a particularly unusual history. Up to 1840 its perihelion distance was a 4.0AU and the comet totally unobservable from Earth. That year there was an encounter with Jupiter and the orbit shifted inwards to a perihelion distance of 3.0AU. From there it slowly decreased further to 2.77AU, from which, in 1959, a further Jupiter encounter moved it in to an orbit with perihelion at just 1.28AU.

This is the 6th return to perihelion. The comet has been seen in 1969 (discovery), 1976, 1982, 1989, 1996 and now 2002. The period is 6.57 years. The comet is unusually active for a short period object and has a coma and often tail even at perihelion, which are almost certainly a result of the comet's big decrease in perihelion distance. During the 2002/2003 apparition the tail has been as long as 10 arcminutes, with a stellar central condensation in a faint extended coma. Even 7 months after perihelion the tail continued to be very well developed, although it faded rapidly from then on.

The comet reaches a magnitude around 12 normally, although this is because the comet has outburst at perihelion at three of its last four returns in 1982/83, 1996/97 and 2002/03 (there is little information on the 1989/90 return). This suggests that perihelic outbursts are a feature of the comet’s light curve. Some studies suggest that there were several outbursts during the 1982/83 return. During the 2002/2003 return two major outbursts can be identified. Despite being a relatively active object, even at the peak of outburst the dust production rate is some 40 times lower than for 1P/Halley. Even so, 67P/Churyumov-Gerasimenko is classed as a dusty comet and is joined in this group by objects such as 1P/Halley, 4P/Faye, 21P/Giacobini-Zinner and 22P/Kopff, as well as non-periodic objects such as C/1975 V1 (West), C/1995 O1 (Hale-Bopp) and C/1996 B2 (Hyakutake). The peak dust production rate in 2002/03 has been approximately 60kg/s, assuming similar dust parameters to the 1982 return in terms of grain size distribution as the values reported by Dave Osip et al., although values as high as 220kg/s were reported in 1982/83 by other observers. The gas to dust emission ratio is approximately 2.

67P/Churyumov-Gerasimenko was selected as the probable new target for the Rosetta mission after the failure to launch the probe in time to meet the narrow window for an encounter with 46P/Wirtanen, although there is an alternative mission profile that would still allow an encounter with 46P/Wirtanen using a Russian booster. After detailed ESA scrutiny though it has been decided in May 2003 that the encounter with 67P/Churyumov-Gerasimenko should be the official new target for the probe. The nucleus of 67P is comparatively large and is estimated as 5km in diameter, as against the estimated 1.4km diameter of 46P/Wirtanen. One of the problems with a ROSETTA encounter with 67P is the fact that the main probe and the lander have been designed to operate in a gravity field 50 times lower and it is not certain how well the probe will respond to the new challenge.

 


The 2002 apparition

G67P/Churyumov-Gerasimenko passed perihelion on August 18th and peaked at around magnitude 12, although there appears to have been an outburst of approximately 2 magnitudes at perihelion. Something almost identical was seen in 1995, although the outburst may have had slightly lower amplitude. On both occasions the rise in the light curve was very fast. It appears that the 1996 outburst came a few days before perihelion, whereas the 2002 outburst was centred exactly on perihelion.

The comet is now fading relatively rapidly, although maintaining considerable activity. Images show a starlike central condensation in the centre of a fainter, extended coma. There is a long, straight tail that was more than 5 arcminutes in length in mid-March in observations by the undersigned with the 82-cm IAC-80 Telescope at Teide Observatory, although apparently fading rapidly. The most recent IAC-80 data taken by Fernanda Artigue and Fabiola Martín-Luis in early April shows that the tail is now much fainter.

CCD aperture photometry and coma profiles are shown below.

 

CCD observations in a 10 arcsecond aperture by:

CCD total magnitude estimates in apertures of 10", 20", 30", 40", 60", 1'.2, 1'.4 and 1'.6 by:

 

Image: August 14th 2002

Image of 67P/Churyumov-Gerasimenko showing a faint tail. 35cm Newton + ST9E CCD. 4x30s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

Image: August 18th 2002

Image of 67P/Churyumov-Gerasimenko showing a hint of a faint tail. Note that the orientation of this image is not the same as that of the August 14th image from Rolando Ligustri. Exposure 30s with a 0.30-m f/5.5 Schmidt-Cassegrain + CCD.

++++++++++++++++++++++++++++++
Ramón Naves & Montse Campàs
rnaves@eresmas.com

MPC 213, OBSERVATORIO MONTCABRER CABRILS (SPAIN)
www.ictnet.es/+mcampas

 

 

 

 

Image: November 9th 2002

Image of 67P/Churyumov-Gerasimenko showing the developing tail. 35cm Newton + ST9E CCD. 6x60s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

Image: November 9th 2002

False colour enlargement of the previous image of 67P/Churyumov-Gerasimenko. 35cm Newton + ST9E CCD. 6x60s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

Image: December 28th 2002

Image of 67P/Churyumov-Gerasimenko showing a faint tail.

++++++++++++++++++++++++++++++
Ramón Naves & Montse Campàs
rnaves@eresmas.com

MPC 213, OBSERVATORIO MONTCABRER CABRILS (SPAIN)
www.ictnet.es/+mcampas

 

 

 

 

Image: January 11th 2003

Image of 67P/Churyumov-Gerasimenko and a satellite trail. 35cm Newton + ST9E CCD. 4x120s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

Image: January 11th 2003

False colour enlargement of the previous image of 67P/Churyumov-Gerasimenko. 35cm Newton + ST9E CCD. 4x120s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

  

Image: February 1st 2003

Image of 67P/Churyumov-Gerasimenko. Note the fine gas tail and the broader, more difuse dust tail. 35cm Newton + ST9E CCD. 2x240s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

Image: February 1st 2003

False colour enlargement of the previous image of 67P/Churyumov-Gerasimenko. 35cm Newton + ST9E CCD. 2x240s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

 

Image: February 25th 2003

Image of 67P/Churyumov-Gerasimenko. The tail is barely visible in this shorter exposure. 35cm Newton + ST9E CCD. 6x30s

++++++++++++++++++++++++++++++
Rolando Ligustri
rolando.ligustri@tin.it

MPC 235, Talmassons (Italy)
www.castfvg.it/fotoccd.htm/comete

 

 

 

 

 

 

 

 

Image: March 2nd 2003

Image of 67P/Churyumov-Gerasimenko showing a faint tail. Note the bright stellar-like central condensation in a faint extended coma.

++++++++++++++++++++++++++++++
Ramón Naves & Montse Campàs
rnaves@eresmas.com

MPC 213, OBSERVATORIO MONTCABRER CABRILS (SPAIN)
www.ictnet.es/+mcampas

 

 

 

 

 

Aperture photometry:

The light curves of the comet in R in apertures of 10, 20, 30, 40 and 60 arcseconds.

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Observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 4589, Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

 

Coma profiles:

The profile of the coma of the comet calculated from photometry in R in apertures of 10, 20, 30, 40 and 60 arcseconds.

++++++++++++++++++++++++++++++
Observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 4589, Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

Coma profile:

The power law index of the coma brightness of the comet calculated from the photometry shown in the previous figures. There is a strong trend to a faster rate of decline of brightness with distance from the nucleus as the comet recedes from perihelion.

++++++++++++++++++++++++++++++
Calculated from observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 458), Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

Corrected light curve:

The magnitude of 67P/Churyumov-Gerasimenko in a constant apertures of 10000km and calculated from the aperture photometry shown above and the coma index against the time from perihelion.

++++++++++++++++++++++++++++++
Calculated from observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 458), Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

 

 

Corrected magnitude against heliocentric distance:

The magnitude of 67P/Churyumov-Gerasimenko in constant apertures of 10000km and 60000km calculated from the aperture photometry shown above and the coma index against the logarithm of heliocentric distance.

++++++++++++++++++++++++++++++
Calculated from observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 458), Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

 

 

Dust production:

The variation of dust production, measured by Af[rho], against the time from perihelion. Note two important outbursts.

++++++++++++++++++++++++++++++
Calculated from observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 458), Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

 

 

 

Dust production:

The variation of dust production against heliocentric distance.

++++++++++++++++++++++++++++++
Calculated from observations by: Isidro Almendros (MPC 212), Ramón Naves & Montse Campàs (MPC 213), Esteban Reina (MPC 232), Rolando Ligustri (MPC 235), Albert Sánchez (MPC 442), Miguel Camarasa (MPC 445), Diego Rodríguez (MPC 458), Julio Castellano (MPC 939), Francesc Baldris (MPC A01), Josep Lluís Salto (MPC A02), Juan Lacruz (MPC J87), Carles Pineda (MPC J91)

 

 

 

 

 

Image: March 8/9th 2003

Image of 67P/Churyumov-Gerasimenko showing a faint tail. The nucleus is now much less prominent and the coma brighter and more difuse than previously, possibly due to poor seeing. S/C 0.25-m f/3.7 Schmidt-Cassegrain + CCD

++++++++++++++++++++++++++++++
Josep Lluís Salto
jlsalt@wanadoo.es

MPC A02, Observatorio de Cal Maciarol (Abrera, Catalonia, Spain)

 

 

 

Image: March 21st 2003

Image of 67P/Churyumov-Gerasimenko showing a faint tail. The bright starlike nucleus is now visible again and the extended coma only faintly visible. 30s exposure.

++++++++++++++++++++++++++++++
Juan Lacruz
juan_lacruz@yahoo.com

MPC J87, Observatorio de La Canada (Madrid, Spain)

 

 

 

 

 

Image: April 20th 2003

Image of 67P/Churyumov-Gerasimenko. The dramatic fade is very evident. The prominent tail has almost vanished and the coma has become extremely difuse.

++++++++++++++++++++++++++++++
Ramón Naves & Montse Campàs
rnaves@eresmas.com

MPC 213, OBSERVATORIO MONTCABRER CABRILS (SPAIN)
www.ictnet.es/+mcampas

 

 

 

 

 

Image: May 3rd 2003

Deep image of 67P/Churyumov-Gerasimenko showing a faint tail. The nucleus is now much less prominent and the coma brighter and more difuse than previously, possibly due to poor seeing. S/C 0.25-m f/3.7 Schmidt-Cassegrain + CCD

++++++++++++++++++++++++++++++
Josep Lluís Salto
jlsalt@wanadoo.es

MPC A02, Observatorio de Cal Maciarol (Abrera, Catalonia, Spain)

 

 

 

 

For the elements and the current ephemeris from the Minor Planet Center click here.

For a daily ephemeris, click here.

For Seichii Yoshida's light curve click here.



Última actualización 30/05/2003
Por M.R.Kidger
Correo electrónico:
mrk@ll.iac.es