Continuum (1.3 mm) and J = 2 − 1 ¹³CO, C¹⁸O, and C¹⁷O line emission towards M1-92. Top: Maps of the continuum (colour map) and high-velocity line emission (contours). The continuum peaks at $\alpha ={19}^{\text{h}}{36}^{\text{m}}18\stackrel{\text{s}}{.}925$ and $\delta =+{29}^{°}32\prime 49\stackrel{″}{.}687$. The full lines show emission in the ¹³CO J = 2 − 1 integrated over the spectral intervals marked in grey in the line plot. Magenta and cyan contours show red-shifted and blue-shifted emission, respectively, at 70%, 50%, 30%, and 10% level of the peak values of 0.115 (red-shifted) and 0.127 (blue-shifted) Jy beam⁻¹ × km s⁻¹. Bottom: Source-integrated spectra of the ¹³CO J = 2 − 1, C¹⁸O J = 2 − 1, and C¹⁷O J = 2 − 1 lines.