GCN Circular 14428
L. Elenin (KIAM), A. Volnova ( IKI), V. Savanevych (KNURE), A. Bryukhovetskiy (NSFCTC), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 130420A (Page et al., GCN 14406) with 0.45-m telescope of ISON-NM observatory on Apr. 20, between (UT) 07:30:54 - 10:51:49. The observation started automatically 144 s after burst trigger. We took several unfiltered images of 30, 60 and 300 s exposures. The optical counterpart of GRB 130418A (Guidorzi et al., GCN 14405; Page et al., GCN 14406; Guver et al., GCN 14407) is clearly visible in single images. Coordinates of the counterpart are (J2000) RA = 13:04:25.56 Dec = +59:25:26.8 with uncertainties of 0.2" coincide with the coordinates reported early (Guidorzi et al., GCN 14405, Guver et al., GCN 14407). A photometry of single and later combined image is based on the SDSS stars with assumed R-magnitude J130421.49+592547.6 R = 16.13 J130416.49+592509.2 R = 16.95 J130443.88+592659.3 R = 14.54 Preliminary light curve can be found at http://grb.rssi.ru/GRB130420A/GRB130420A_lightcurve_ISON-NM.png The light curve is clearly exhibit a fast rise and peaked with 16.1 mag at ~0.0207days after burst trigger following steep power law decay and later at 0.05 days swallowing to the typical afterglow power law.