image. Therefore, strongly lensed supernovae can be detected and distinguished from ordinary non-lensed supernovae if they appear as spatially and temporarily coincident transients [@Ogu2010a] or exceptionally bright transients [@Gold2017]. In the following, we outline each observational strategy and the related detection criteria in more detail.

Image multiplicity
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The critical factors for detecting multiple images are the image separations relative to the seeing, the flux contrast between the images and the apparent magnitudes of the faintest images in the configuration. As a base model for this strategy we adopt detection criteria optimized for the Large Synoptic Sky Survey (LSST), as proposed by @Ogu2010a. Following this approach, a transient is identified as a strongly lensed supernova if *i*. the maximum image separation $\theta_{\rm max}$ between images falls into a range between $0.5''$ and $4''$, where these limits stem from seeing conditions as well as the choice of selecting systems lensed by isolated galaxies, characterized by relatively simple lens models, *ii.* the flux ratio between the images for doubly imaged supernovae is larger than 0.1 and *iii.* at least three or two images are detected for quads/cusps (four/three images) and doubles (two images), respectively. For sufficiently bright supernovae and a suitable survey 