1SWASP J140747.93-394542.6 Type: Eclipsing binary; T Tauri AAVSO lightcurve (2020 ) AAVSO lightcurve (index) Eclipsing binary systems are binary systems with orbital planes so close to the observer's line of sight (the inclination of the orbital plane to the plane orthogonal to the line of sight is close to 90 deg.) that the components periodically eclipse each other. Consequently, the observer finds changes of the apparent combined brightness of the system with the period coincident with that of the components' orbital motion. T Tauri stars showing periodic variability due to spots. For those members of this class where special features are well known, the subtype classifications of CTTS/ROT or WTTS/ROT may be applied. Where not precisely known, the subtype of TTS/ROT is used. When their properties are well-known, they are classified in two sub-groups: CTTS (Classical) and WTTS (Weak-lined). GCVS types IT and INT. AAVSO Alert 462: June 25, 2012 Dr. Eric Mamajek, Cerro Tololo Interamerican Observatory and University of Rochester, has requested AAVSO observers' assistance in monitoring the young star 1SWASP J140747.93 -394542.6 to help determine the eclipse behavior related to a transiting ringed substellar companion. The young star underwent a series of symmetric, deep eclipsing events in April/May 2007, consistent with a transiting substellar companion surrounded by a complex ring system moving in front of the star. The series of eclipses were of depth ~0.5-3 magnitudes and occurred over a 52-day period. Unfortunately only a single eclipse sequence was seen, and the period of the ringed companion (likely to be a brown dwarf or giant planet) and the exact scale of the ring system remain unknown. We are gathering observations to test whether this may constitute a moon- forming "protoexosatellite” disk. The unusual nature of this star was discovered by E. Mamajek & M. Pecaut in December 2010, and details of the eclipses and characterization of the eclipsed star are described in Mamajek et al. 2012, Astronomical Journal, Vol. 143, 72 (http://arxiv.org/abs/1108.4070). We are asking for nightly photometry in one or more visible photometric bands (preferably V) to search for the start of the next eclipse. This star is no longer being monitored by the surveys that led to the initial discovery of this object. A brightness dip of more than ~0.15 magnitude in V will indicate the transit of the outermost ring, with additional deeper transits leading up to the central transit approximately 3 weeks later, where an eclipse depth has been measured of at least 3 magnitudes in V band.