Optical investigations of GRBS 960720 and 970402

We present results of optical investigations of error boxes of GRBs 960720 and 970402. For GRB960720, we have investigated numerous archival plates ta ken at the Sonneberg Observatory to look for any kind of optical activity, especially from the position of radio-loud QSO 4C 49.29. One optical bright ening/flare has been found at this position, indicating optical activity of the quasar. Additional observations have been obtained in Ondrejov and are also presented and discussed. The error box of GRB970402 has been also inv estigated on archival plates at Sonneberg and Bamberg Observatories. These data have been evaluated together with recent deep CCD frames. No optical a ctivity has been found except the variable star BL Cir just at the edge of the error box. More details regarding the optical behavior and nature of th is object are presented.