PEGASE (Fioc & Rocca-Volmerange 1997, assuming an exponentially declining star formation rate) suggested the ages of the dominant stellar population between 2 to 5 Gyrs. This implies that the major star formation event of LSBG galaxies took place at much later stages (at z$\sim$0.2 to 0.4).

These studies show that the ages of LSBGs are in debate, and could spread in a wide range, although the working sample is small in these investigations. Surely much more efforts and much larger sample are needed for detailed studies on the ages of LSBGs. Moreover, most of these investigations are based on optical photometry which has obvious shortcoming in estimating ages of galaxies. As we know, the youngest stars may dominate the ultraviolet (UV) and optical part of the spectrum, and an old stellar component will thereby be extremely difficult to detect. With the inclusion of NIR broadband photometry one would expect to be able to constrain the ages more strictly (Bell et al. 2000; Zackrisson et al. 2005). The UV data are also needed to build SEDs of galaxies in a wider range, which will help to derive ages of galaxies more reliably. At present, the modern digital sky survey in large 