The observations were obtained using direct CCD imaging on the 1-m telescope at Siding Spring Observatory from September to November 1991. All Himages were 900 s exposures. R images were obtained immediately before or after each H image in order to avoid the possibility of stellar variability affecting our measure of emission strength. A Tektronix 10241024 CCD with pixels of scale 0.6 was used for these observations, giving us an imaged area of typically 1010 (compared with 5.75.7 in Grebel (1997). V and I images were obtained at the same time for some fields, and in some cases on other nights using a GEC 7701152 CCD. A log of the observations is presented in Table 1.
The CCD images were processed with IRAF and the photometry of the fields was done using the DoPHOT photometry package (Mateo & Schechter 1989). Standard magnitudes in V and I were derived from the standards used in Sebo & Wood (1994) and from magnitudes given by Walker (1996). The R and H magnitudes were not standardised and colours have an arbitrary zeropoint.
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