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Special Notice #388: Outburst of VSX J213806.5+261957

October 23, 2014: Carey Chiselbrook (Georgia, United States; AAVSO observer code CCY) observed the WZ Sge-type dwarf nova VSX J213806.5+261957 in outburst at a visual magnitude of 9.7 on 2014 October 22.0590 (JD 2456952.55903). Prior to the outburst detection,  the last observation (also by CCY) indicated the star was not in outburst less than 24 hours prior (mvis < 13.8 at JD 2456951.6326). This star was first discovered in May 2010, and both Eddy Muyllaert and Gary Poyner (via the BAAVSS mailing list) note that its recurrence time of less than five years makes it notable among stars of this class. Gary Poyner also notes that this object is on the BAA Recurrent Objects Programme, with the name 1RXS J213807.1+261958. Both visual and time-series instrumental observations of VSX J213806.5+261957 are strongly encouraged. CCD time-series observers may notice superhump oscillations appear within the next few days, having a period near 0.06 day (~ 1.5 hours).

Observers should note that the variable lies within a few arcseconds of a 15th magnitude star, and it may not be possible to separate the two once the variable falls below 15th magnitude.  Please indicate in the comments field of your observations whether you are able to split the two stars.

VSX J213806.5+261957 is located at the following (J2000) coordinates:

RA: 21 38 06.68   Dec: +26 19 56.6.

Charts with a comparison star sequence for VSX J213806.5+261957 may be created using the AAVSO Variable Star Plotter (VSP,

Please report all observations of this star via the WebObs feature of the AAVSO website, and using the name "VSX J213806.5+261957".

This AAVSO Special Notice was prepared by M. Templeton.


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