conditions from the observed quantity K. The net flux in the $\rm H\alpha$ line is given by:

1truemm $net~flux~=~{cnts^g_{on}\over T_{on}~\tau_{on}~c}-{cnts^g_{off}\over T_{off}~\tau_{off}~c}~=~
{cnts^g_{on}~-~K~cnts^g_{off}\over T_{on}~\tau_{on}~c}~~~~~[erg~cm^{-2}~s^{-1}]$ 1truemm

that requires a determination of c from the calibration process. In order to calibrate our data, we have observed the spectrophotometric stars Feige34, Hz44 and BD332642 just before or after the target galaxies. Their measured spectral energy distributions (available in IRAF in tabular form) were then convolved with the filter transmission profiles to obtain the value of c.

Results
=======

Fig. 3a gives a gray-scale representation of the off (top panels) and net (on-off, bottom panels) frames of all galaxies with a net flux. Fig. 3b carries the off-frames of 11 galaxies with null or negative net flux.[^2]

Table 3 reports the results of the present work as follows:

Col. 1: CGCG galaxy name. Col. 2: telescope used. Col. 3: total equivalent width ($\rm \AA$) from the present work, jointly with its statistical uncertainty. Col. 4: logarithm of the integrated flux from the present work ($\rm erg~cm^{-2}~s^{-1}$). Col. 5: logarithm of the integrated luminosity ($\rm erg~s^{-1}$). The last two quantities are given only for targets observed under photometric conditions. Col. 6, 7: equivalent width, with error 