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Alert Notice 368: Major Outburst of EX Lup

January 29, 2008: Further to AAVSO Special Notice #93, the pre main-sequence eruptive variable EX Lup (AAVSO 1556-40) appears to be  undergoing a major outburst, exceeding the previous brightest maximum recorded in 1955. Albert Jones (Nelson, NZ) reports that EX Lup reached a visual magnitude of 7.9 on 2008 Jan 29.66 UT (JD 2454495.1600). This exceeds the previous brigtest recorded magnitude of this object (m(vis) = 8.7 on JD 2435385.9 and 2435459.1) in 1955-56.  

During the current episode of activity, the star underwent an initial outburst that reached a maximum of m(vis) = 9.5 on 2008 January 19.6236 UT (JD 2454485.1236); it subsequently faded erratically to a minimum of m(vis) = 10.7 on 2008 January 23.6181 UT, after which it began to rise again.

Recent observations reported by Albert Jones indicate a rapid rise since January 23: m(vis)=10.4 at 2008 Jan 26.64  (JD 2454492.14); m(vis)=9.5 at 2008 Jan 28.63 (JD 2454494.13); and m(vis)=7.9 at 2008 Jan 29.66 (JD 2454495.16).

Observers are urgently requested to observe this star during the current outburst. Both visual magnitude estimates and filtered instrumental photometry are requested.

EX Lup is located at RA: 16:03:05.5 , Dec: -40:18:25 (J2000)

Charts for EX Lup may be generated with VSP:

http://www.aavso.org/vsp

The most recent observations of EX Lup may be found by going to the WebObs observation search page (replaces QuickLook):

http://www.aavso.org/apps/webobs/search

Please report all observations to the AAVSO as "EX LUP".

This AAVSO Alert Notice was prepared by Matthew Templeton.

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