C/2002 T7 (LINEAR)

When, on October 14^th 2002 LINEAR discovered a magnitude 17.5 asteroidal object it was not suspected that this would be the most important object of the year. Within days it had been confirmed as cometary by various observers and further LINEAR data had been located from October 12th.

On investigating its orbit it was found that it would reach perihelion at 0.61AU on April 23rd 2004 and potentially could become nearly magnitude 0, although, of course, such long-range extrapolation is fraught with danger. The comet is in a retrograde orbit of inclination 161º. A curiosity is that its path in the sky in May 2004 will cross that of C/2001 Q4 (NEAT) and it is possible that the two comets will be simultaneously visible to the naked eye in the same visual field in the evening sky.

Click here to for a study of the light curve and prospects for activity (Updated: 21/08/2003).

Click here to for a comparison of prospects for activity with C/2001 Q4 (NEAT) (Updated: 29/12/2003).

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The light curve

The light curve is only poorly covered at present and although the comet may become very bright in May 2004 it is still very uncertain just how bright the comet will be. The comet is of Halley class, with an absolute magnitude of +4.5, thus it is about 2 magnitudes brighter than the average new comet. This means that although it is intrinsically a fairly bright object, and gets close enough to the Sun to become bright, without the danger of disruption, much depends on just how close it gets to the Earth. In this sense it seems that the close approach to Earth after perihelion is secure, but a few days difference in the perihelion pass date could have quite a significant effect on the light curve.

At present the estimate based on a 4th power law would suggest that the comet should reach magnitude +1, but if the brightening is slower, as it often is, it would make the comet 2-3 magnitudes fainter. It is thus highly premature to suggest that it will be a bright object, although it should be naked-eye.

The light curve is very sensitive to the geocentric distance. The light curve has been brightening rapidly from discovery, although there was a sharp change in slope in early 2003.

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
• Julio Castellano - MPC 939
• Juan de la Cruz - MPC J87
• Carles Pineda - MPC J91
• Toni Climent - MPC J97
• Josep Lluis Salto - MPC A02
• Giovanni Sostero

Última actualización 29/12/2003
Por M.R.Kidger