TITLE:   GCN CIRCULAR
NUMBER:  2832
SUBJECT: GRB 041006: GETS Optical Afterglow Observation
DATE:    04/11/05 04:25:03 GMT
FROM:    Kenzo Kinugasa at Gunma Astro. Obs/Japan  <kinugasa@astron.pref.gunma.jp>

K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.)
report:

 Starting at 12:50:19 UT on 2004 October 6 (32 minutes after the burst
trigger), the sky area of GRB041006 (Galassi, et al. GCN 2770) was
observed with the GETS (0.25-m robotic telescope equipped with 
unfiltered CCD in the Gunma Astronomical Observatory). The observation 
continued for 6.5 hours and 30-s exposure frames were obtained.

 We stacked 20 original frames into a single frame and find that the
optical afterglow (Da Costa, et al. GCN 2765) is detected in the
stacked frames. Between 12:57 and 14:55 UT (mean epoch), we obtained
10 independent measurements and the afterglow faded from Rc=17.8 to 
Rc=18.7 by using a comparison star from Henden's calibration (GCN 2801).

 After 15:02 UT, intermittent clouds came to cover the field of view and
the afterglow was not detected.