Аннотация:MASTER OT J122114.34+472950.7 - PSN MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 12h 21m 14.27s +47d 29m 51.4s on 2013-03-28.48019 UT. The OT unfiltered magnitude is 16.8m (limit 17.9m). The OT is seen in 4 images. We have reference image without OT on 2013-02-21.6928 UT with m_lim=18.3. The object was already present on Mar. 21.757 and 25.462 UT MASTER-Amur images at 17.7+/-0.3m but was not detected automatically then.