GRB 040916 - optical limits

HETE alert 3558 - details - GCN 2712 - GCN 2713 

NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    3558,   Seq_Num: 2
GRB_DATE:       13264 TJD;   260 DOY;   04/09/16
GRB_TIME:       209.70 SOD {00:03:29.70} UT
The burst consists of two peaks separated by ~250s, each ~100s in duration;
the dearth of counts in bands > 10 keV in either peak is a strong indication that GRB040916 is an XRF. 
90% confidence error box with corners at the following coordinates (J2000):
RA = 23 02 01.68,         Dec = -05 50 09.6
RA = 23 00 23.76,         Dec = -05 37 51.6
RA = 23 00 58.80,         Dec = -05 19 51.6
RA = 23 02 36.72,         Dec = -05 32 09.6

"Pi of the Sky" observations

The central part of HETE FOV containing GRB040916 error box was observed by "Pi of the Sky" apparatus at Las Campanas Observatory for the night of 2004.09.15/16
from 00:20:54 UT (17 min after the GRB) till 09:05 UT.
10s exposures were taken continuously with 4s intervals by two CCD cameras.
No unknown objects wrt Tycho-2 and GSC catalogues has been observed within the GRB040916 error box.
The limiting magnitude is ~11.5m for single frames and ~13m for 20 coadded frames.

frame 58
00:20:54 - 00:21:04 UT		 frames 58-77
00:20:54 - 00:25:56 UT

The field shown covers 100x100 arcmin (1 arcmin/pixel) centered at the GRB error box (South up).