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Astron. Astrophys. 342, 809-822 (1999)

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3. Data reduction and line identification

3.1. Data reduction

The data were reduced using the Starlink spectral line package SPECX. Linear baselines were subtracted from the spectra and the line parameters of peak temperature ([FORMULA]), central frequency ([FORMULA]) and line width at half maximum ([FORMULA]) were measured. Values for the noise in the spectra were evaluated using line-free channels and the typical rms noise level was found to be [FORMULA] 0.1 K. Features below the detection limit of 5[FORMULA] were ignored to avoid inaccurate line identifications. It should be noted that only one feature below 5[FORMULA] was seen which was tentatively identified as the 7(8)-6(7) line of SO, however the line was very weak with a peak temperature of only 0.2 K and has been neglected from any further analysis. These data are given in Table 1 for each line. Multiple independent detections of each line are listed (i.e. from both the main and the 10 MHz shifted spectra). Self-absorbed lines have been excluded from the analysis and are indicated as such in Table 1.


[TABLE]

Table 1. The measured line parameters of observed frequency ([FORMULA](obs)), peak temperature ([FORMULA]) and line width ([FORMULA]) for each detected line are listed here. Multiple detections of the same line have been included. Lines that are blended are indicated in the Notes column by blended if they are blended with a different species or hyperfines if they are a mixture of two or more hyperfine components. Self-absorbed lines are also listed.


3.2. Line identification

Eighteen lines from 11 species (including isotopomers) were detected in this survey. The lines were identified by comparing their central frequencies to those of the lines detected in the spectral line survey of Paper I. The spectral line lists used to identify the lines in Paper I include Lovas (1992), Poynter & Pickett (1985), Anderson, Herbst & De Lucia (1993) and the observational list of lines seen by Jewell et al. (1989) towards Orion-KL. The identified lines are listed in Table 1. All our detected lines were identified with those also seen at the central position of Paper I.

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© European Southern Observatory (ESO) 1999

Online publication: February 23, 1999
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