Astron. Astrophys. 322, L25-L28 (1997)

2. Observations

The ¹² CO J 3-2 ( GHz) observations presented in this work were carried out in March and October 1994 at the James Clerk Maxwell Telescope ¹ (JCMT) on Mauna Kea, Hawaii. The ¹³ CO J 3-2 ( G Hz) observations were obtained during JCMT service time in November 1995. We used the B3i receiver in conjunction with the Dutch Autocorrelation Spectrometer (DAS). The beamwidth was at 345 GHz. We integrated for several minutes per point, achieving typical rms noise levels of 0.1 K. The integration time for the ¹³ CO J 3-2 observations was 30 minutes per point and typical rms noise levels of 0.02 K were obtained. These observations were done with the aim of estimating the optical d epth of the ¹² CO emission from the ratio of the ¹² CO to the ¹³ CO intensities (see Goldsmith et al. 1984).

Figure 1 shows an optical image of the HH 1-2 region. The solid box represents the area around VLA 1 mapped by us in CO J 3-2 with resolution. The ¹³ CO J 3-2 data were obtained only on three positions around VLA 1. We have also mapped in CO J 3-2 an area of aproximately around VLA 3. This area is shown as a dashed box in Fig. 1. Two positions were observed in ¹³ CO J 3-2 in the direction of VLA 3.

Fig. 1. The HH 1-2 region in the optical. The solid box represents the area centered in VLA 1 and mapped by us. This area is shown in Fig. 3. The dashed box corresponds to the area mapped by us around VLA 3. This area is shown in Fig. 5. The optical image was obtained using the Digitized Sky Survey from SkyView

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

helpdesk.link@springer.de