The design, spectral coverage and sensitivity of Isophot-S, one of the four sub-experiments of Isophot, are described. Isophot-S is a low resolution near infrared spectrometer, designed to take full advantage of the Infrared Space Observatory (ISO) telescope with its low infrared background, wide field of view, and the complete absence of

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We have recently introduced a new algorithm, the implicit integral method (IIM), for solving radiative transfer problems in which the specific source functions (for each frequency and direction) depend linearly on the radiation field via a single quantity which is independent of both frequency and direction. We define this kind of relationship as

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We present kinematical evidence that the irregular galaxy located 26'' northwest of IZw18 -the most metal-poor blue-compact-dwarf (BCD) galaxy known- is a dynamically associated companion system. Longslit CCD spectra were obtained in 1996 February using the 4.2m WHT+ISIS at La Palma, with the slit placed across the NW HII region of IZw18 and

The narrow-band optical images in several of the most important atomic lines and neighbouring continuum were secured at Las Campanas Observatory (LCO) in 1994 March 17-22, using the 40-in. telescope (LCO-40) and the TEK1 1024x1024 pixel detector. The narrow-band filters are centred in the following emission lines: H{beta}, [OIII] 5007{AA}, Hα, [NII