C/2002 Q5 (LINEAR)

This comet was discovered by LINEAR on August 28th 2002 and its cometary nature confirmed by Spanish amateur Jaime Nomen at Ametlla de Mar (Catalonia). This is an object of very low activity and was expected to reach only magnitude 15 at maximum despite having its perihlion at 1.24AU. The orbit is retrograde with an inclination of 149 degrees.

The light curve

Coverage of the light curve is now quite extensive with observations from a number of observers. In theory the comet was at maximum or very close to maximum when discovered and will fade slowly until March 2003 when a much more rapid rate of fade will start. The actual observations seem to be showing though that unexpectedly the comet was brightening rather rapidly initially despite the fact that it was expected to have peaked. This may be due to an outburst similar to that seen in C/2001 A2 (LINEAR).

The most recent observations are a little contradictory. It seems though that there was a very rapid brightening through most of September and that the comet may still be increasing slowly in brightness even in early October. Additional monitoring will show whether or not this is really the case.

When we separate the data by observer we find some inconsistencies. This is probably due to two principal factors:

(i) Occasional problems with the magnitudes of field stars (a study finds that a small proportion of measures will have very large photometric errors despite being reduced with the same care and in the same way as other data)

(ii) Differences in the response curves of CCDs that mean that some unfiltered data is very close to the standard R-band, but other observers are producing photometry closer to V than to R. In this case there is a problem if a catalogue such as USNO is being used, as USNO lists B and R. To get a pseudo-V magnitude one must use the mean of the USNO "B" and "R".

Although apparently very little extended, the measures taken with larger apertures than the standard 10 arcseconds show a quite significant increase in integrated magnitude from R=15.7 in a 10" aperture to R=14.7 in a 30" aperture on September 10th.

 

CCD observations in an aperture of 10 arcseconds by:

CCD aperture photometry in apertures of 0'.2 and 1'.2 by:

 

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.

 

 

Image: September 13th 2002

Animation of C/2002 Q5 (LINEAR) taken with a 0.30-m f/6.5 Schmidt-Cassegrain + ST9-E CCD from close to Barcelona (Spain).

The comet shows a quite rapid movement. Although obviously slightly difuse the coma is very small and the activity low despite being almost at the orbit of Mars. This image has pixels of approximately 2 arcseconds.

++++++++++++++++++++++++++++++
Ramón Naves & Montse Campàs
rnaves@eresmas.com
MPC 213, OBSERVATORIO MONTCABRER CABRILS (SPAIN)
www.ictnet.es/+mcampas

 

 

 

 


Última actualización 31/05/2003
Por M.R.Kidger
Correo electrónico: mrk@ll.iac.es