Discovery science image of TUVO-21acq (left), the template image used in the image-subtraction process (middle), and the resulting difference (right). Images are 150″ by 150″. North is up and east is left. The red lines in the science image indicate the position of the transient. The Observation ID (ObsID) of the science image is 00013908006 (extension 2); the ObsID of the template image is 00084458002 (extension 1). The artefacts visible in the difference image result from the image subtraction process (see Modiano et al. 2022 for details). Photometry is only performed on the science and template images; difference images are only used for detection of transients.