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Astron. Astrophys. 325, 685-692 (1997)

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2. Submillimetre observations

We carried out continuum observations from 350 µm to 1.3 mm with the UKT14 common user bolometer receiver (Duncan et al. 1990) on the 15-m James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii, in October 1993 and March 1994. The 65 mm aperture was used. The FWHM beamwidth varied between 17[FORMULA] and 20[FORMULA], depending on the filter. A chop throw of 60[FORMULA] was used with a chopping frequency of 7.8 Hz. Calibration was mainly referred to OMC1 (which, being close to L1641, had a similar air mass) and checked with secondary standards from the JCMT calibration source catalogue (Sandell 1994).

The observations were carried out by pointing at the coordinates given by Chen & Tokunaga (1994; see their Table 5) which correspond to the near IR counterparts of the IRAS sources (for VLA1, not detected in the near IR, we used the VLA coordinates). Then a small map was carried out at 800 µm in order to define the peak emission position (given in columns 2 and 3 of Table 1). At this position, photometry at 1.3 mm, 1.1 mm, 800 µm and, when possible, at 350 and 450 µm was carried out.


Table 1. Sources properties and observed submillimetre fluxes

For all sources except S22 and S32, for which the displacement is less than 18[FORMULA] , the submillimetre emission peak has been found within 10[FORMULA] (0.022 pc) of the reddest near IR source. This coincidence (within the JCMT spatial resolution) proves that the objects are very young and still embedded in their parental cloud. Table 1 lists the results of our observations.

Column 1 gives the source name (given by SNS). Columns 2 and 3 give the coordinates of the aperture center. The bolometric luminosities (and uncertainties) determined from our calculations (see Sect. 3.1) are given in column 4. The outflow status, outflow (OF) or non detected flow (NDF) given in column 5, refers to the Saraceno et al. (1996) classification. For the VLA1 outflow, we refer to Correia et al. (1996). Columns 6 to 10 give, in janskys, the submillimetre fluxes from 350 µm to 1.3 mm, together with the total error (which includes statistical, photometric and absolute calibration uncertainties estimated at 10% level). No corrections for spectral beam size variations have been applied as they are negligible compared to total flux errors.

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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998