Map of the 230.9 GHz or 1.3 mm continuum emission observed with the SMA, combined with the scaled single-dish SCUBA 1.3 mm emission derived in Sect. 2.3. Contours are –6, 6, 10, 14, 18, 22, 26 and 30 × 4 mJy beam^-1. Greyscale: –20 to 150 mJy beam^-1. The synthesised beam is the same as the SMA-only image, and is shown in the bottom left corner: 4.3′′ × 2.7′′, PA = 4.0°. The plus sign marks the position of the water maser reported by Lis et al. (1994) and the crosses mark (from north to south, respectively) the positions of the 1.3 cm sources VLA 4 to 6 from Rodríguez & Zapata (2013). The dashed black contour shows a column density of 2 × 10²² cm^-2 for β = 1.75, used as the outer boundary of the cloud when determining its total mass.