The common characteristics of the four stars is the low amplitude, which can explain the difficulty in obtaining reliable light curves from photographic observations. The light curve of HV 1353 is typical of a fundamental mode pulsator, and this is confirmed by the low order Fourier parameters, which have normal values for SMC Cepheids (Beaulieu & Sasselov 1996). A possible explanation for the low amplitude of HV1353 is a companion or a background star with comparable luminosity. This would imply also a lower intrinsic luminosity of the Cepheid by several tenths of a magnitude, placing the star well below the continuous line in Fig. 8; the unknown reddening could alleviate the discrepancy. Figure 8 shows the position of our stars in the PL diagram, compared with the relation reported by Laney & Stobie (1994, continuous line) valid for fundamental mode pulsators, the relation for first overtone mode pulsators (dotted line) derived assuming a period ratio P1/P0=0.70, and the relation for second overtone mode pulsators (dashed line) assuming P1/P2=0.80. The magnitudes of our stars, however, were not corrected for reddening and for the SMC tilt effect (Laney & Stobie 1994).
HV 1777, HV 1763 and HV 1779 have light curves, low order Fourier parameters, periods and amplitudes similar to those of SMC first overtone mode Cepheids with similar period (Beaulieu & Sasselov 1996), and also the position in the PL diagram confirm the first overtone pulsation of HV 1777 and HV 1763. The position of HV 1779 would be compatible with the second overtone pulsation.
Only one measurement of V-R is available for each star. Taking into account the low amplitude and the phase of the observations, the V-R values for HV 1353, HV 1763 and HV 1779, which are 0.40, 0.27 and 0.27, respectively, should be close to the true mean color value within few hundredths of a magnitude, while in the case of HV 1777 the observation (V-R = 0.26) was made when the star was near the maximum light.
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