Abstract. We present the first results of an observational programme at the ESO Very Large Telescope aimed at detecting a large sample of high-redshift galaxies fainter than the current spectroscopic limit of R = 25.5 for Lyman-Break galaxies. In this paper, we describe the results of deep narrow and broad-band imaging and subsequent follow-up multi-object spectroscopy of faint high-redshift galaxies in the fields of the QSOs BRI 1346−0322 and Q 2138−4427. These QSOs have intervening high neutral hydrogen column density absorbers, at redshifts z = 2.85 and z = 3.15 respectively, for which redshifted Lyα emission falls within less than a few Å from the central wavelengths of existing VLT (∼60 Å-wide) narrow-band filters. We selected 37 and 27 candidate emission-line galaxies in the two fields respectively. Most (∼85%) of the candidates have R-band magnitudes fainter than R = 25.5. The first spectroscopic follow-up of a sub-sample of the candidates resulted in 41 confirmed candidates and 4 foreground emission line galaxies (three [O ] emitters and one C  emitter). The confirmation rate for Lyα emitters is 82% and 68% in the field of BRI 1346−0322 and Q 2138−4427 respectively. In addition, we serendipitously detect a number of other emission-line sources on some of the slitlets not used for candidates. Of these, 9 are also most likely Lyα emitters with redshifts ranging from 1.98 to 3.47. The redshift distribution of confirmed candidates in the field of BRI 1346−0322 is consistent with being drawn from a uniform distribution weighted by the filter response curve, whereas the galaxies in the field of Q 2138−4427 have redshifts clustering very close to the redshift of the damped Lyα absorber. This latter fact indicates the existence of a large "pancake"-like structure confirming the earlier suggestions of Francis & Hewitt (1993).

Abstract. We present the discovery of the optical transient of the long-duration gamma-ray burst GRB 000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04 ± 0.08. The transient displayed a power-law decline characterized by a decay slope of α = −1.035 ± 0.097. A deep image obtained 25 days after the burst shows no indication of a contribution from a supernova or a host galaxy at the position of the transient. The closest detected galaxy is a R = 24.68 ± 0.15 galaxy 2.0 arcsec north of the transient. The magnitudes of the optical afterglows of GRB 980329, GRB 980613 and GRB 000630 were all R > ∼ 23 less than 24 hours from the burst epoch. We discuss the implications of this for our understanding of GRBs without detected optical transients. We conclude that i) based on the gamma-ray properties of the current sample we cannot conclude that GRBs with no detected OTs belong to another class of GRBs than GRBs with detected OTs and ii) the majority ( > ∼ 75%) of GRBs for which searches for optical afterglow have been unsuccessful are consistent with no detection if they were similar to bursts like GRB 000630 at optical wavelengths.