2. Observations and data reduction
The spectra were taken the 20. - 24. February 1987 at the ESO/MPI 2.2-m telescope on La Silla (Chile) using the Boller & Chivens spectrograph. The spectral resolution was about 1.6 Å/pixel and the spatial resolution was /pixel. The spectra were reduced following standard procedures, were normalized and wavelength calibrated. In these spectrograms we measured row by row the line intensity integrated over the line width. For a few pixels that were dead or hit by a cosmic ray we interpolated the intensity from the neighbouring unaffected pixels. The background, as well as continuum emission from an extended reflection nebula (e.g., at the base of the HH 46/47 jet), was measured to both sides of the lines and subtracted. We then calculated the line ratios that are necessary for our diagnostic technique (see below) row by row.
© European Southern Observatory (ESO) 1999
Online publication: February 23, 1999