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Astron. Astrophys. 351, L5-L9 (1999)

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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 [FORMULA] per pixel on the 256[FORMULA]256 NICMOS3 arrays used for the two infrared channels and [FORMULA] on the 1024[FORMULA]1024 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).

[FIGURE] Fig. 2. I band finding chart from the DENIS images. The chart size is [FORMULA], with North up and East left.


Table 1. Basic parameters of the objects. LHS102A is satured in the EROS images, so its µ and [FORMULA] are from van Altena et al. 1995. [FORMULA] and [FORMULA] are for epoch J2000.0.

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© European Southern Observatory (ESO) 1999

Online publication: November 2, 1999