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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.
Ghost imaging is usually based on optoelectronic process and eletronic computing. We here propose a new ghost imaging scheme, which avoids any optoelectronic or electronic process. Instead, the proposed scheme exploits all-optical correlation via the
The Milky Way hosts on average a few supernova explosions per century, yet in the past millennium only five supernovae have been identified confidently in the historical record. This deficit of naked-eye supernovae is at least partly due to dust exti
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d binary consisting of a B3 III star and an unseen companion in a circular
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Based on optical correlations, ghost imaging is usually reconstructed by computer algorithm from the acquired data. We here proposed an alternatively high contrast naked-eye ghost imaging scheme which avoids computer algorithm processing. Instead, th