The Naked-eye Optical Transient OT 120926

A previously unknown optical transient (OT 120926) has been observed in the constellation Bootes. The transient flared to magnitude 4.7, which is comparable to the visual magnitudes of the nearby stars $\pi$ Boo and $\omicron$ Boo. Database searches do not yield an unambiguous identification of a quiescent counterpart of this transient but do identify several candidates. However, none of the candidate stellar counterparts have shown any credible evidence of previous variability in the All-Sky Automated Survey or the Catalina Real-time Transient Survey. A flare on the nearby high proper motion, probable M dwarf star LP 440-48 could have produced OT 120926, but the amplitude of the flare would be an unprecedented 11.3 magnitudes. The current record amplitude for such flares on M dwarfs is 9.5 magnitudes.