3. DENIS photometry
We obtained I, J and Ks photometry for 12 of the 25 candidates in the course of the DENIS survey. DENIS observations are carried out on the ESO 1m telescope at La Silla, with a three-channel infrared camera (Copet et al. 1999). Dichroic beam splitters separate the three channels, and focal reducing optics provides image scales of per pixel on the 256256 NICMOS3 arrays used for the two infrared channels and on the 10241024 Tektronix CCD detector of the I channel. DENIS photometry is an efficient estimator of spectral type or approximate effective temperature for M and L dwarfs (Delfosse et al. 1999). Two of the 12 objects clearly have colours typical of L dwarfs, with I-J larger than 3.5 (see Table 1). Fig. 2 gives finding charts for these new L dwarfs. High and medium resolution optical spectra obtained at the Keck telescope confirm their L dwarf status, and are discussed in two separate papers (Basri et al. 1999, Martín et al. 1999).
Table 1. Basic parameters of the objects. LHS102A is satured in the EROS images, so its µ and are from van Altena et al. 1995. and are for epoch J2000.0.
© European Southern Observatory (ESO) 1999
Online publication: November 2, 1999