(All news more than 3 months old will normally be moved to an archive file)
2008/05/26 - 7P - Outburst update
Mark Kidger (European Space Agency European
Space Astronomy Centre) reports on behalf of the "Observadores_cometas" Group
that additional photometry and images have been reported that confirm the
outburst of 7P/Pons-Winnecke reported tentatively in TA Electronic Circular
2449.
Aperture photometry has been reported by Gustavo Muler (MPC J47, Lanzarote,
Spain), Cesar Piret (MPC J46, Lanzarote, Spain), Jose Maria Ruiz (MPC J40,
Malaga, Spain). The photometry suggests that the outburst had already filled a
60" diameter aperture and was decaying when detected by Muler on 2008 May 23.9.
Nightly mean R magnitudes from the above observers are:
2008 May 16.9 - 10", 18.43; 20", 18.23; 30", 17.19
2008 May 17.9 - 10", 18.46; 20", 18.27; 30", 17.93
2008 May 24.0 - 10", 16.06; 20", 15.36; 30", 15.09
2008 May 24.9 - 10", 16.62; 20", 15.76; 30", 15.43
2008 May 25.9 - 10", 16.87; 20", 15.79; 30", 15.39
Images show a rapidly expanding coma which is now more extended than a 1/r
profile, with a faint straight tail visible to the south-east on 2008 May 24.9.
Images of the outburst evolution are available at
http://www.astrosurf.com/comets/cometas/7p/imagenes/7p.html and a light
curve of all 2008 aperture photometry data at
http://www.astrosurf.com/comets/cometas/7p/image010.gif
2008/05/16 - 46P - Outburst
Mark Kidger (European Space Agency, European Space Astronomy Centre) reports on behalf of the “Observadores_cometas” group that 46P/Wirtanen has experienced a significant outburst. Recent R magnitudes in different apertures are:
2008 May 06.9: 10”, 16.76; 20”, 15.75; 30”, 15.20 (Francisco Hernandez, MPC J24, Tenerife, Spain)
2008 May 12.9: 10”, 17.09; 20”, 16.10; 30”, 15.4.9 (Gustavo Muler, MPC J47, Lanzarote, Spain)
2008 May 15.9: 10”, 14.96; 20”, 14.21; 30”, 13.74 (Jose Ramon Vidal, MPC 945, Gijon, Spain)
2008 May 16.9: 10”, 15.11; 20”, 14.41; 30”, 13.98 (Cesar Piret, MPC J46, Lanzarote, Spain)
Images and the multiaperture photometry show that the inner coma has become significantly more condensed, with the coma slope changing from considerably more extended than 1/r pre-outburst, to being 1/r or slightly steeper at the peak of the outburst.
The light curve of the outburst can be found at: http://www.astrosurf.com/comets/cometas/46p/may_2008_outburst.htm
Images of the current outburst are available at: http://www.astrosurf.com/comets/cometas/46p/imagenes/46p.html
Observers are strongly encouraged to follow the evolution of this apparently unique light curve event in this object, which has shown highly consistent light curve behaviour in its previous apparitions.
Background information:
The values of Afrho obtained by the “Observadores_cometas” group during the 2007/08 apparition have, up to the current outburst, been identical to within about 10% to those obtained during the 2002 apparition at the same time relative to perihelion, which themselves show an almost identical behaviour to the 1996 apparition (Kidger, 2004, Astron.Astrophys., 420, 389-395). In other words, this comet has shown highly consistent and reproducible light curve behaviour over its last 3 apparitions.
The comparative values for 2002 and 2008 at current and past epochs are:
2002: T-8d (r=1.06AU), Afrho=170cm; T+61d (r=1.33AU), Afrho=36cm; T+102d (r=1.66AU), Afrho=11cm
2008: T-7d (r=1.06AU), Afrho=190cm; T+61d (r=1.33AU), Afrho=38cm; T+103d (r=1.67AU), Afrho=83cm
2008/03/10 - 17P - micro-outburst (17P/Holmes page)
THE ASTRONOMER Electronic Circular No 2430
2008 Mar 10 10.10UT - Guy M. Hurst
COMET 17P/HOLMES - Mark Kidger and Richard Miles have sent the following
report:
Images and photometry by several observers, including Ramón Naves and Montse
Campàs (MPC 213), Martin Mobberley (MPC 480, reduced by Montse Campàs), Faustino
García (MPC J38), Gustavo Muler (MPC J47) and Richard Miles (J77), suggest that
comet 17P/Holmes has shown a further mini-outburst, which appears to have
initiated on 2008 March 7. The three events detected so far have taken place at
44.6+/-0.6, 89.5+/-0.6 and 135.1+/-0.8 days after the initial outburst on 2007
October 23.7, giving a mean interval of 45.0 +/-0.5 days determined from a least
squares fit. The correlation coefficient of the fit is r2=0.99997. It is likely
that this periodicity corresponds to the rotation period of the nucleus whereby
the same area is activated when receiving insolation and thus it is concluded
that 17P/Holmes is a very slow rotator, comparable to 29P/Schwassmann-
The following analysis by Richard Miles adjusted to constant heliocentric
distance; delta and phase angle (rel. March 7 20:00 UT) shows the
development of the current outburst. Photometry is for a 10 arcsec square
aperture, equivalent to a physical aperture of 22000 km at the comet. The
amplitude of the brightening is currently about 0.4 magnitudes.
Date Time
R Mag. Outburst amplitude MPC Code
March 4 21:21 UT 16.05 -0.02 mag.
J77
March 5 21:00 UT 16.02 -0.03 mag.
J47
March 5 21:10 UT 16.06 +0.01 mag.
J38
March 7 19:56 UT 15.88 -0.21 mag.
213
March 7 20:00 UT 15.97 -0.12 mag.
480
March 7 23:15 UT 15.77 -0.32 mag.
J47
March 8 21:55 UT 15.72 -0.38 mag.
J47
March 8 22:03 UT 15.70 -0.40 mag.
J47
___________________________________________________________
Noticias calientes:
(Todas las noticias con más de 3 meses de antigüedad pasarán
normalmente a un fichero de archivo histórico)
16-05-2008 - 46P - Outburst
Mark Kidger (European Space Agency, European Space Astronomy Centre) reporta de partre del grupo “Observadores_cometas” que el cometa 46P/Wirtanen ha experimentado un significativo outburst. Recientes magnitudes en R y otras aperturas son::
2008 May 06.9: 10”, 16.76; 20”, 15.75; 30”, 15.20 (Francisco Hernandez, MPC J24, Tenerife, Spain)
2008 May 12.9: 10”, 17.09; 20”, 16.10; 30”, 15.4.9 (Gustavo Muler, MPC J47, Lanzarote, Spain)
2008 May 15.9: 10”, 14.96; 20”, 14.21; 30”, 13.74 (Jose Ramon Vidal, MPC 945, Gijon, Spain)
2008 May 16.9: 10”, 15.11; 20”, 14.41; 30”, 13.98 (Cesar Piret, MPC J46, Lanzarote, Spain)
Las imágenes y la fotometría multiapertura muestran que la coma interior se ha hecho considerablemente más condensada.
Podeis ver la curva de luz del outburst en: http://www.astrosurf.com/comets/cometas/46p/may_2008_outburst.htm
Las imágenes en: http://www.astrosurf.com/comets/cometas/46p/imagenes/46p.html
Animamos a los observadores a seguir la evolución de este acontecimiento, al parecer único en este objeto, que ha mostrado un comportamiento sumamente constante en sus apariciones anteriores.
Información de fondo:
Los valores de Afrho obtenidos por el grupo
"Observadores_cometas" durante la aparición 2007/08, hasta el outburst,
han sido idénticas en un 10%
aproximadamente a aquellos obtenidos durante la aparición 2002 al mismo tiempo
en relación con el perihelio, ellos mismos muestran un comportamiento casi
idéntico a la aparición 1996 (Kidger, 2004, Astron. Astrophys., 420, 389-395).
En otras palabras, este cometa ha mostrado el comportamiento de curva sumamente
constante y reproductivo sobre sus 3 últimas apariciones.
Los valores comparativos hacia 2002 y 2008 en la corriente y épocas pasadas son:
2002: T-8d (r=1.06AU), Afrho=170cm; T+61d (r=1.33AU), Afrho=36cm; T+102d
(r=1.66AU), Afrho=11cm
2008: T-7d (r=1.06AU), Afrho=190cm; T+61d (r=1.33AU), Afrho=38cm; T+103d (r=1.67AU), Afrho=83cm
10/03/2008 (Página del 17P/ Holmes)
Esta mañana ha salido publicada una circular electronica en THE ASTRONOMER (Circular No 2430 2008 Mar 10 10.10UT - Guy M. Hurst) donde se indica el informe enviado por Mark Kidger y Richard Miles sobre los últimos acontecimientos del 17P/HOLMES . Imagenes y fotometria de varios observadores, incluidas las de Ramón Naves y Montse Campàs (MPC 213), Martin Mobberley (MPC 480, reducidas por Montse Campàs), Faustino García (MPC J38), Gustavo Muler (MPC J47) y Richard Miles (J77), sugieren que el cometa 17P/Holmes ha sufrido un mini-outburst, que parece haber iniciado el día 7 de marezo de 2008. Los tres acontecimientos detectados hasta ahora en 44.6+/-0.6, 89.5+/-0.6 y 135.1+/-0.8 días después del estallido inicial del 23 de octubre de 2007, estos dan un intervalo de 45.0 +/-0.5 dias.El coeficiente de correlación es de r2=0.99997. Es probable que esta periodicidad corresponda al período de rotación de nucleo por lo que la misma área es activada recibiendo insolación, concluyendo que el cometa 17P/Holmes tiene una rotación muy lenta, comparable con el 29P/Schwassmann-Wachmann 1, que de las observaciones Spitzer (Stansberry J.A., et al., 2004, ApJ Suppl. Ser., 154, 463) parece girar con un período de 60 días o más.
El análisis siguiente, de Richard Miles, se adaptó a la distancia de heliocentrica constante; delta y ángulo de fase (rel. 7 de marzo 20:00 UT) muestra el desarrollo del estallido. La fotometría es para una abertura de 10 x10 arcsec , el equivalente con una abertura física de 22000 kilómetros en el cometa. La amplitud del mejoramiento es actualmente aproximadamente 0.4 magnitudes.
Date Time
R Mag. Outburst amplitude MPC Code
March 4 21:21 UT 16.05 -0.02 mag.
J77
March 5 21:00 UT 16.02 -0.03 mag.
J47
March 5 21:10 UT 16.06 +0.01 mag.
J38
March 7 19:56 UT 15.88 -0.21 mag.
213
March 7 20:00 UT 15.97 -0.12 mag.
480
March 7 23:15 UT 15.77 -0.32 mag.
J47
March 8 21:55 UT 15.72 -0.38 mag.
J47
March 8 22:03 UT 15.70 -0.40 mag.
J47