Swift J1913.1+1946: Optical photometry

Following the detection of the bright hard X-ray and optical transient Swift J1913.1+1946 (Dichiara et al., GCN 32632; Lipunov et al., GCN 32634), which is possibly a GRB (Kennea & Williams, GCN 32635; Veres et al., GCN 32636), photometric observations were obtained using a 0.28-meter SCT telescope equiped with a Moravian G2-1600 CCD camera and Astrodon Johnson-Cousins BVRcIc filters. The observations started at 19:13:48 UT on 2022-10-09. Five 180 s exposures were average combined for each filter. The following magnitudes were measured using three APASS DR9 field stars. The APASS DR9 r' and i' magnitudes were transformed to Cousins Rc and Ic using the Jester et al. (2009, AJ 130, 873) relations. The afterglow was not detected in the B filter with a 5-sigma upper limit of B = 17.8. Date [UT] Filter mag ------------------- ------ --------------- 2022-10-09 19:21:21 B >17.8 (5-sigma) 2022-10-09 19:36:30 V 17.48 +/- 0.02 2022-10-09 19:51:40 Rc 16.60 +/- 0.05 2022-10-09 20:06:50 Ic 15.76 +/- 0.06 These magnitudes are not corrected for galactic extinction.