CS(2–1) profiles (Lee et al. [@lmt01]).

In section 2 of this paper, we describe our observational procedure. In section 3 we present the observational results deriving the physical characteristics of the source and analysing its chemical and kinematical properties. In section 4 we discuss the observational results and the summary can be found in Section 5.

 Observations
=============

The observations were carried out between April 2002 and January 2003 at the IRAM-30m in three different runs.

In April 2002, we observed the core in (1-0), (3-2), (2-1) and (3-2). In general, we used the symmetric frequency switch mode and the facility autocorrelator; in Table \[tsettings\], we summarize the main observational parameters. The frequencies of the (1–0), (2–1) and (3–2) have been updated following the recent determinations of Dore et al. ([@dcb03]); the values in the table refer to the $F_1 \, F$ = 2 3 $\rightarrow$ 1 2, 2 3 $\rightarrow$ 1 2, and 4 5 $\rightarrow$ 3 4 hyperfine components of the (1–0), (2–1) and (3–2) transitions, respectively. For (3–2) we used the frequency of the 2 1$\rightarrow$1 0 component as determined by Caselli et al. ([@cas02a]). In the case of the April 2002 (3-2) observations, in order to 