Example of translational and rotational offset between two UVOT images of the same field, taken around one month apart. The image is composed of two stacked UVOT UVW1 exposures of the field of Nova Per 2020. The ObsIDs and extensions of the images are 00013909005[1] and 00013909010[1]. The position angle of the telescope was ~40° offset between the two images (320° for ObsID 00013909005; 280° for ObsID 00013909010). The displayed images clearly show the result of this rotational offset, as well as a translational offset due to the pointing accuracy of Swift. Searches for transients can be performed within the overlapping area. To prepare images for alignment and image subtraction in PII, the images are cropped (and saved to two new images) so as to contain only the overlapping area.