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                        PLANET ANOMALY UPDATE
		             2004 #13-1
                      (issued 26-Jul, 14:20 UT)
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               PLANET observations reveal limb darkening



Dear Colleagues,

dense observations over the course of the caustic exit of event 
OGLE 2004-BLG-309 carried out by PLANET with the SAAO 1.0m telescope at
Sutherland (South Africa) between HJD = 2453206.226 (19-Jul, 17:25 UT) and
HJD = 2453206.514 (19-Jul, 0:20 UT) will provide not only a precise measurement
of the relative proper motion between lens and source, which will constrain
lens mass and distance, but also show a strong signal of limb darkening.

After the caustic exit peak, which occured at HJD = 2453206.31 +/- 0.01 
(19-Jul, 19:26 UT +/- 15 min) at a magnification of ~ 2.8 mag above baseline, 
the event faded by about 2.4 mag until the trailing limb of the source exited
at HJD = 2453206.441 +/- 0.007 (19-Jul, 22:35 UT +/- 10 min), depending on   
the assumed amount of limb darkening which might be quite substantial and
smoothen the light curve at this epoch. 

After the caustic exit, the event brightened again by about 0.8 mag until
a peak around HJD = 2453209.3 +/- 0.15 (22-Jul, 19:00 UT +/- 4 h) and is now 
expected to approach a Paczynski-curve asymptotically. 

Event:            OGLE 2004-BLG-309
RA (J2000):       17:58:28.26
Dec (J2000):      -28:03:29.0

The baseline I magnitude reported by the OGLE team is 18.20.

For more information:
PLANET:  http://planet.iap.fr/currentevents.html
OGLE:    http://www.astrouw.edu.pl/~ftp/ogle/ogle3/blg-309.html

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On behalf of the PLANET collaboration,

Martin Dominik 

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