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Astron. Astrophys. 345, 181-186 (1999)

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2. Observations

Full scans of the spectrum of HD 142527 in the 2.4-45 µm range with the Short Wavelength Spectrometer (SWS) (de Graauw et al. 1996) and in the 43-200 µm range with the Long Wavelength Spectrometer (LWS) (Clegg et al. 1996) on board of ISO have been obtained on March, 1st 1996. The integration times were respectively 2046 and 2441 seconds.

The SWS-spectrum and LWS-spectrum were reduced using the latest version of the standard pipeline. This resulted in a oversampled spectrum in which every single detector (48 for SWS, 10 for LWS) is wavelength- and flux-calibrated. Remaining instrumental effects, such as fringes (periodic flux oscillations) and glitches (cosmic impacts exciting the detector), still had to be corrected for, which has been done using the instrumental analysis packages (IA) provided by the instrument teams. In order to increase the S/N, the most outlying data points have been removed using a statistical rejection criterium with [FORMULA]=2.5. After aligning the different detector signals and rebinning to the expected resolution (R [FORMULA] 300), we obtained the final result. The full SWS-LWS spectrum of HD 142527 is shown in HD 142527's spectral energy distribution on Fig. 1. The independently reduced SWS and LWS spectrum match almost perfectly, confirming the detector alignment performed. However, a discrepancy between the LWS-spectrum and the 60 and 100 µm IRAS-fluxes is observed. No explanation for this mismatch has been found.

[FIGURE] Fig. 1. Spectral energy distribution of HD 142527, normalized to the V-band. UV-continuum fluxes, derived from spectra obtained with the International Ultraviolet Explorer IUE, optical Geneva photometry, near-IR ESO-photometry, near-IR fluxes derived from IRSPEC near-IR spectroscopy obtained at ESO, as well as IRAS broad-band photometry are represented by triangles. A Kurucz-model ([FORMULA] = 6250 K, log g = 4.0 and solar metallicity) and the ISO-spectra are overplotted.

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© European Southern Observatory (ESO) 1999

Online publication: April 12, 1999