HIP 53449. Top: observed CO(2−1) line profile at a velocity resolution of about 2 km s^-1 (histogram), and a typical fit of a shell profile (line, see text). Middle: observed CO(3−2) line profile at a velocity resolution of about 2 km s^-1. Bottom: observed CO(3−2) line profile at a lower resolution of about 4 km s^-1 (histogram), and a typical fit of a shell profile (line, see text). The velocity scale is heliocentric (the conversion from LSR velocity is done within CLASS).