Photometric observations of V1054 Oph (Wolf 630 AB, m v = 9.69) and of the comparison star HD 152678 (m v = 8.1) were carried out in the UBV bands at Catania Astrophysical Observatory on 1994, June 15, using the 91 cm Cassegrain telescope equipped with an improved version of the twin-beam photometer URSULA (De Biase et al. 1988). We have detected a relatively low-intensity flare event preceded by a pre-flare dip of low amplitude and the exceptionally long duration of 36 min. The integration times were 10, 5 and 5 sec in the U, B and V bands, respectively. The variable and the comparison stars were observed simultaneously in the two independent channels of the twin-beam photometer. The sky background was subtracted from the photon count rates of V1054 Oph and its comparison star in each spectral band, and the flux of the variable was normalized to that of the comparison star.