... afterglows''

Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii.

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... IRAF

IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

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... MB

Dealing with smaller data sets makes the treatment much faster and guarantees the permanent availability of the whole survey database on a commercial machine with moderate disk space (about 300 GB).

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...$\mu _{\rm max}$

The $\mu _{\rm max}$ is the magnitude of the brightest pixel of the object.

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... stars''

Since stars are point sources $\mu _{\rm max}$, the brightness of their brightest pixel, is exactly proportional to their magnitude when the image is well oversampled. On a given CCD frame the difference $\mu _{\rm max}$-magnitude is constant for stars, which follow a well defined "line'' in a plot showing $\mu _{\rm max}$-magnitude as a function of  $\mu _{\rm max}$. The position of this "line'' can change according to the observing conditions.

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...Contaminated

An object close to a bright object.

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... of 05AQ05

A run at the CFHT is named according to the following designation: two numbers for the year, two letters for the semester (AQ for the first semester and BQ for the second one), and two numbers for the period of observation.

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... objects

Since a single object appears in only one image, this value, which includes cosmic rays, has to be divided by 3 to be compared to the matched objects number.

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... magnitude

The power law decay implies that the beaming factor is low and the afterglows are faint during 90% of their lifetime.

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... detection

Images taken with different filters cannot be compared.

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