TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2514
SUBJECT: GRB040106: Second Epoch Optical Observations
DATE:    04/01/09 05:21:47 GMT
FROM:    Derek Fox at CIT  <derekfox@astro.caltech.edu>

D.B. Fox and S.B. Cenko (Caltech) with R. Phelps (NSF) report:  

"We have observed the error circle of the Integral GRB 040106
(Mereghetti et al., GCN 2505) on a second occasion with the Swope
40-inch telescope at Las Campanas Observatory, commencing Jan 8.28 UT.
Observations consisted of 2x600 s exposures in I-band, reaching R ~ 21
mag.

Comparison of these images to our first-epoch T2-band imaging (Price
et al., GCN 2509) reveals that the two faint sources (a) and (b) which
lie within the region of the XMM X-ray afterglow localization (Ehle,
Gonzalez-Riestra & Gonzalez-Garcia, GCN 2508) have not changed in
brightness since our first epoch, retaining the same flux to +/- 0.1
mag.

The two brighter sources within the XMM localization, which are
visible in the archival images of the DSS2, have also not varied
significantly in brightness between our two epochs (+/- 0.1 mag).  We
thus identify no candidate optical counterparts within the XMM
localization, and establish a limit of R>~21 on the brightness of any
typical such counterpart at either of our epochs of observation."