Comment on "Simultaneous lateral and endwall high-speed visualization of ignition in a circular shock tube" [Combustion and Flame 214 (2020) 263-265]

We have found an inaccurate claim in the recent publication titled "Simultaneous lateral and endwall high-speed visualization of ignition in a circular shock tube", by Figueroa-Labastida and Farooq [1]. The authors of this publication stated in the third paragraph of the introduction the following, "To our knowledge, this study demonstrates the first simultaneous endwall and lateral imaging of ignition in a shock tube." This claim is found to be incorrect as Ninnemann et al. [2] demonstrated the first simultaneous endwall and sidewall measurements inside a circular (cylindrical) shock tube during iso-octane/air/Ar ignition.