  We report early follow-up observations of the error box of the short burst
050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada
(OSN), followed by deep VLT/FORS2 I-band observations obtained under very good
seeing conditions 5.7 and 11.7 days after the event. Neither a fading
afterglow, nor a rising SN component was found, so the potential GRB host
galaxy has not been identified based on a comparison of the two VLT images
taken at different epoches. We discuss if any of the galaxies present in the
original 10 arcsec XRT error circle could be the host. In any case, the optical
afterglow of GRB 050813 was of very low luminosity. We conclude that all these
properties are consistent with the binary compact merger hypothesis for the
progenitor of GRB 050813.

Astrophysics