Adjustment and estimates of the parameters of the lightcurves

To determine the parameters of the lightcurves, we applied the procedures described in chapter table . The magnitudes are expressed there in filters UBV Johnson-Cousins corrected for Galactique absorption then brought in the filters of the reference frame of the supernovæ, i.e. , corrected for the K-correction.

The factor of stretching was estimated in an independent way in each filter. Its value is expressed in the system defined by our model of lightcurve. One will use relations 9.12 to pass in the system defined by goldhaber2001.

We indicate each time an estimate of the corrections which were applied:

• The K-correction in each filter.
• Galactic absorption in each filter.

We point out that these corrections are made directly at the time of the adjustment.

Lastly, we indicate it $\chi^2$ per degree of freedom for each adjustment. The great values correspond in general to atypical supernovæ like 1998de which has a factor of small stretching (0.62). Figure 10.4 shows its lightcurve in flux in the filter B We clearly see on this example that the factor of stretching does not make it possible to bring the model on the data for the points beyond a score of days after the maximum of luminosity. We see here the operational limits of the factor of stretching.

Figure 10.4: Curve of light of 1998de resulting from batch CFA 1997-2000. This under-luminous supernova has a redshift of 0.015 and one factor of stretching of 0.62.