(a) ALMA 0.89 mm (Band 7) continuum image of G358.93−0.03, with an angular resolution 0.″46 × 0.″42 (∼3000 au at 6.75 kpc). The contour levels are 3.5 mJy beam⁻¹ (1σ) × (8, 12, 24, 48, 72, 96, 144, 240, 336); the continuum components are labeled for reference. Integrated intensity (b) and velocity (c) images of the CH₃CN J = 11₄–10₄ transition (Band 5 data, beam 0.″55), with the 0.89 mm contours from (a) are overlaid. The location of the (sub)millimeter masers is indicated by the blue × symbol in (b). (d–g) Spatially integrated maser spectra for (d) SMA, near 200 GHz; (e) SMA, near 340 GHz; (f) ALMA, for three of the same lines as panel (d); and (g) ALMA, for four of the same lines as panel (e). The brightness temperature (T_b) scales (shown in kiloKelvin) are computed with respect to the synthesized beam, not the fitted size.