GRB 040825A - optical limits

HETE GCN alert data

NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    11553,   Seq_Num: 2
GRB_DATE:       13242 TJD;   238 DOY;   04/08/25
GRB_TIME:       12630.00 SOD {03:30:30.00} UT
WXM_CNTR_RA:    344.744d {+22h 58m 59s} (J2000),
WXM_CNTR_DEC:   -10.934d {-10d 56' 01"} (J2000),
WXM_MAX_SIZE:   14.00 [arcmin] diameter

"Pi of the Sky" observations

The central part of HETE FOV containing GRB040825A error box was observed by "Pi of the Sky" apparatus at Las Campanas Observatory for the night of 2004.08.25
from 2:24 UT (1 h 6 min before the GRB)
till 9:35 UT (6 h 4 min after the GRB).
10s exposures were taken continuously with 4s intervals by two CCD cameras.
The single frame limiting magnitude was strongly varying, due to thin clouds covering the sky.
No OT and no unknown objects have been observed within the GRB040825A error box.
Preliminary limits for frames preceding, containing and following the GRB are the following:

frame 308
-21s - -11s
limit 10m		 frame 309
-7s - +3s
limit 10m		 frame 310
+7s - +17s
limit 9.5m

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

We are working on better limits for integrated frames. Results will be posted at this page.

Observing conditions were varying, as can be seen from the following plots. The GRB t0 (frame #309) unfortunately happened in a local minimum of sky visibility.