$\star$ The choice of the fields of observation

As we saw in chapter 2 , Galactique absorption is dependent on the direction of observation. Thus to allow the observation of extragalactic objects such as the supernovæ, it matters that this one is minimum in the fields selected for research.

Moreover, the construction of the curve of light imposes that the fields are visible lasting at least two to three months following the discovery of the supernovæ.

Lastly, the follow-ups spectroscopic and photometric can be carried out since of the observatories in the southern hemisphere. One thus needs visible fields since all the sites. They are thus selected with weak variation and observable since the two hemispheres.

The same field was selected for the campaigns of springs 2000, 2001 and 2002. It is located in field VIRMOS at 14h+05, and presents tiny a Galactique absorption: $E(b-v)=0.03$, that is to say an absorption 0.05 magnitude out of I.