The observations were carried out on February 1990 with the 37 m radio
telescope at Haystack Observatory. We observed the (J,K) = (1,1) and the
(J,K) = (2,2) inversion transitions of the ammonia molecule. At the
observing frequencies (23.6944960 GHz and 23.7226320 GHz, respectively),
the beam size of the telescope is
, and its beam efficiency at
an elevation of
is
. We used a dual maser
receiver and both polarizations were observed. The spectrometer was a
1024-lag digital autocorrelator with an effective bandwidth of 6.67 MHz.
The calibration was made with the standard noise-tube method. The
observations were made in the position switching mode. All the spectra
were corrected for the elevation-dependent gain variations and for
atmospheric attenuation. The rms pointing error was estimated to be
by observing continuum unresolved sources. System temperature
ranged from 70 to 150 K. The data were reduced using the CLASS and GREG
packages of IRAM. The observed spectra were smoothed, resulting a
velocity resolution of
.
We searched 15 sources for (1,1) emission. In all cases, we first made
measurements on a five-point grid centered at the positions given in Table
1 (click here), with a full beam separation between points. The
(1,1) line was
detected in 14 of these sources. The
(2,2) line was observed in 8
sources, at the positions given in Table 2 (click here), and was detected in 6 of them.
Spectra of the
(1,1) and
(2,2) lines obtained at the positions given
in Table 2 (click here) are shown in Figs. 2 (click here) and 2 (click here), respectively. In Figs. 3.1 (click here) to 3.10 (click here),
3.11 (click here) to 3.12.1 (click here), and 3.13 (click here), we show the
(1,1) maps of the detected sources.
Table 1: Sources observed in or
In Table 2 (click here) we give (1,1) and (2,2) line parameters obtained from a
multicomponent fit to the observed spectra at the position of the emission
peak, using the CLASS package. In Table 2 (click here) we list physical parameters of
the high-density cores, derived from the ammonia observations following
the procedures explained in the footnotes of the table.
Table 2: line parameters
Table 3: Physical parameters of the condensations
Additionally, we searched for the 6
maser line (at
the observing frequency of 22.235080 GHz) in nine sources. We made five
or seven-point maps centered at the positions given in Table 1 (click here). For the
water maser observations, we used the same spectrometer with the same
bandwidth as for the ammonia observations. We reached a typical
sensitivity of 1.5 Jy (
) per spectral channel. We detected
\
maser emission towards the region associated with the source IRAS
20188+3928 and the spectrum obtained is shown in Fig. 2 (click here). For the other
observed sources we do not detect any significant (
)
\
emission.
Figure 1: Spectra of the (J,K)=(1,1) inversion
transition of the molecule towards the positions given in Table 2,
for the detected sources. The vertical axis is the main beam brightness
temperature and the horizontal axis is the velocity with respect to that
of the center of the main line (given in Table 2)
Figure 2: Same as Fig. 1, for the (J,K)=(2,2) inversion
transition
Figure 3: Spectrum of the maser detected near IRAS
20188+3928, towards the position
,
, as observed in Feb. 10, 1990