and $R_e$ in arcsec, position angle and axis ratio. Without distance estimates, we cannot determine whether these systems pass the common defining criteria for UDGs, $R_e \ge 1.5$ kpc, and some of these galaxies may actually be dwarf galaxies at small distances. The redshift by association (defining high density regions in terms of normal galaxies and assigning SMUDGes to the redshift of that overdensity) worked for 25 candidates in Stripe 82 and all 25 satisfy the $R_e > 1.5$ kpc criterion at the assigned distance. Only 1 has $R_e > 6$ kpc, which seems to be about the upper limit on size - it has $R_e = 8.6$ kpc - which suggests that this one may have the wrong redshift. In this particular case, the UDG candidate is close in projection to a nearby bright galaxy and so it may instead be a satellite of that galaxy (Zaritsky et al., in prep). Therefore, we work under the hypothesis that we have a sample of UDGs with low contamination by dwarf galaxies, but we examine this issue again further below.

S-PLUS DR1 data
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We use data from the first data release (DR1), which covers an area of 336 deg$^{\text{2}}$ in 