Photometric study of the improved GRB 970815 error box

An improved error box of GRB 970815 has been reported very recently (Smith et al.1999). This error box is consistent with the decaying X-ray source detected by ROSAT, which strongly supports the source as the GRB X-ray afterglow. We report a re-analysis of the follow up observations performed in 1997 containing the improved RXTE error box. No variable optical/IR source has been found neither within the entire RXTE error box nor within the ROSAT and ASCA X-ray circles. Upper limits for any transient object are K<SUP>'</SUP>>=18 (Aug 17 1997), B>=21.5, R>=22 (20 Aug 1997), B>=22.5 and R>=23 (23 Aug 1997). Also we report additional BVRI optical observations performed in 1999 of the ROSAT X-ray source aimed to detect the host galaxy of GRB 970815. .