performing fitting of the galaxies in all detected bands of the data. Considering that the star formation history (SFH) of galaxies is difficult to determine from photometric data alone, and that simulations indicate that UDGs may have bursty SFHs [@2017MNRAS.466L...1D; @2018MNRAS.478..906C], we assume that s may be described by a , such that

$$f_\lambda(\lambda) = f_0 \cdot \text{SSP}(\text{[Fe/H]}, \text{Age}, z)10^{{-0.4 A_\lambda}}$$

where $f_0$ is a scale factor for the spectral flux density of the galaxy, $\text{SSP}$ represents a single stellar population model that depends of the metallicity (\[Fe/H\]) and age, and the redshift $z$ of the galaxy, and $A_\lambda$ represents a dust-screen attenuation model. One important cautionary point about the use of to represent a potentially more complicated SFH is that the derived properties are luminosity weighted. As appreciated previously [cf. @2007MNRAS.374..769S], luminosity-weighted ages are expected to be biased toward the youngest populations, in contrast to the luminosity-weighted metallicity, which reflects more closely the mass-weighted average.

Considering both the low of the observations and the low spectral resolution of the photometric system, we expect that derived parameters may be correlated, as is the case in the well-known age-metallicity degeneracy problem [@1994ApJS...95..107W], and that some parameters will not be properly estimated. 