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AAVSO Alert Notice 368: Major Outburst of EX Lup AAVSO HOME > publications > alert notice

AAVSO 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:

The most recent observations of EX Lup are available here:

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

This AAVSO Alert Notice was prepared by Matthew Templeton.


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