In March 1997 was carried out spectroscopy with the 3.6-m telescope of the next object, discovered from the pair of plates, separated by 14 years (1979–1993) (at the limit of sensitivity: its apparent magnitude in R band was about 19.5), through its large proper motion, and its spectrum was found very red, very peculiar and very odd-looking.

Ruiz et al. named this brown dwarf Kelu-1: «kelu» means «red» in the Mapuche language (the origin of the second part of the name—the number «1»—is unexplained in the article).

The discovery paper of Kelu-1 by Ruiz et al. was received 1997 September 5, accepted for publication 1997 October 16 and published 1997 November 6 in The Astrophysical Journal Letters.

[14] However, observations of Kelu-1 with near-infrared camera NICMOS on Hubble Space Telescope carried out on 1998 August 14, did not reveal the presence of any companion with separation greater than 300 mas and magnitude difference less than 6.7 mag.

[15][5] In 2005 the binarity hypothesis proved true: the second component (Kelu-1 B) was discovered with the Laser Guide Star Adaptive Optics (LGS AO) system on 10-meter Keck II Telescope, Mauna Kea Observatory, Hawaii, by Gelino et al.[5] and independently by Liu and Leggett.

[6] Gelino et al.observed Kelu-1 with infrared camera NIRC2 using LGS AO system on 2005 March 4 and 2005 April 30, and it appeared to be a binary object with a separation about 290 mas.

HST did not detect the companion in 1998 August observations, as it turned out, because its separation increased for 1998–2005 due to orbital motion, and in 1998 it was several times smaller.

[5] Liu & Leggett independently observed Kelu-1 on 2005 May 1 also with NIRC2 using LGS AO system on Keck II Telescope, and also discovered the companion Kelu-1 B (a separation was 291 ± 2 mas).