UVM2 light curve and the different image stamps of the transient detected using TUVOpipe at RA = 22:02:43.26, Dec = +42:16:40.0. This source is the prototype BL Lacertae object, a highly variable blazar that is frequently observed by Swift and is therefore often detected as a transient by our pipeline. It was the target of the Swift observations. The red points indicate data points obtained on images that may not have been successfully aligned in the pipeline (see Sect. 3.3.1). In Fig. 29, the long-term (PV) light curve of this source is displayed.