2 Observations

All observations were obtained at the 0.6-m telescope of the Instituto Astronômico e Geofísico, University of São Paulo, at the Pico dos Dias Observatory of the Laboratório Nacional de Astrofísica, Brazil. Light curves were observed in five nights in August 1997. A Bfilter was used throughout in order to inhibit the contamination of the measurements by the strongest nebular emission lines (in particular H$\alpha$). Moreover this facilitates a comparison with the results of GB83 who have also observed most of their light curves in B. The integration time was $90^{\rm s}$, with a dead time of $8^{\rm s}$ between integrations. A back-illuminated EEV CCD was used as detector. A journal of the observations is given in Table 1.

 

 

Table 1: Journal of observations of MT Ser.

	HJD
Date	(2450000+)	$N^\ast$
1997 Aug. 22	683.403-.589	144
1997 Aug. 23	684.488-.562	65
1997 Aug. 25	686.401-.580	153
1997 Aug. 26	687.400-.575	154
1997 Aug. 27	688.405-.573	148

$\parbox{6.9cm}{$^\ast$\space Number of integrations.}$