Figure 7: Coadded -band image of GRB 090628 taken with the 1.23 m telescope. The large circle represents the preliminary XRT error circle [18], whereas the small one shows the refined one [20] reported for GRB 090628. The field of view of the image is . The total exposure time is 3120 s. The individual images were taken in June 28.9486–29.0225 UT (1.43–3.20 hours after the gamma-ray event). No objects were found in both error circles down to . More detailed information can be found in [21].