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Astron. Astrophys. 333, L63-L66 (1998)

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2. Observations

Using the full wavelength range available with the two grating spectrometers on board ISO we have obtained a continuous spectrum from 2.4 to 190 µm of the star MWC 349 (Thum et al. 1998). More than 160 emission lines were detected, most of which are recombination lines of hydrogen. In particular, all hydrogen [FORMULA] -line s H [FORMULA] are detected, from [FORMULA] to 9 at very high signal-to-noise with the Short Wavelength Spectrometer (SWS; de Graauw et al. 1996) and from [FORMULA] to 15 with the Long Wavelength Spectrometer (LWS; Clegg et al. 1996). The fluxes of these lines, which are unresolved with both spectrometers, are listed in Table 1. Errors are dominated by uncertainties of the calibration, which we estimate as 25% (SWS) and 35% (LWS) from residual flux differences between overlapping detectors and from comparison with a few ground-based measurements. A few of the [FORMULA] -line fluxes were corrected for weak blends with higher order transitions or, in one case (H [FORMULA]), for a strong blend with an [OIII] transition.


Table 1. Fluxes [FORMULA] of the H [FORMULA] recombination lines observed with ISO. Transitions from [FORMULA] to 9 falling into the SWS range have a typical spectral resolution [FORMULA]. With the LWS the resolution is [FORMULA] m for transitions [FORMULA] to 12, and [FORMULA] m for [FORMULA] to 15.

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© European Southern Observatory (ESO) 1998

Online publication: April 20, 1998