May 2001, but a problem in the guidance of the telescope did not make
it possible to carry out these observations. The follow-up began only
on May 7 and was prolonged until June 18. The closest supernovæ (with redshifts around 0.5, 2001go, 2001gq and 2001gy) were followed in two filters F675W and F814W which corresponds to the bands R and I 2000fr moreover gained from a follow-up in the filter F555W (which corresponds to the band V). The most remote supernovæ (2001gn and 2001hb) as for them were followed in filters F814W and F850LP. The supernovæ best followed were observed at 5 different periods, the least best observed gained 3 periods of observations. For the details of the observations, one will refer to the appendix B .
These supernovæ have be discovered around April 20, 2001 (except 2000fr
which was discovered in April 2000) and gained from spectroscopic
identification the following days (around April 25). The first
observations were projected for April 30 and
May 2001, but a problem in the guidance of the telescope did not make
it possible to carry out these observations. The follow-up began only
on May 7 and was prolonged until June 18.
The observations all were carried out in Planetary Camera (PC) which has the finest pixelisation and thus a better space sampling of the supernova and its galaxy host. Moreover, to reduce the effects of inefficiency of transfer of loads, the supernovæ were observed in the low part of the CCD, near of the amplifier to reading. Lastly, the zone was selected in such manner to avoid all the known defects of the CCD.