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OBSID:
26247
 Title:
The wide angle outflow of SGRB 210726A       
Investigator:
Schroeder
 Observer:
Schroeder, Genevieve
 Phone:
3156512567
 Email:
genevieveschroeder@u.northwestern.edu
Target Name:
SGRB 210726A
 Sequence Number:
402356
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_00914B
 Raster Scan:
N
 Annotated DOT:
DEC3021a

Proposal Number:
22408825
 Right Ascension:
193.291
 Declination:
19.1902
 Status:
archived
 Start Date:
2021-12-31 18:52:51
Category:
BH AND NS BINARIES
 Type:
DDT
 AO Cycle:
22
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
0.000175
 Order-1 Count Rate:

 Exposure Time:
40
 Time Remaining:
36.753
 Reqd Start Time:

 Reqd Stop Time:
Period:

 Epoch:

 Start of Period:

 End of Period:

 PS Margin:

 PE Margin:

 Max Segments:
0

ACIS Mode:
TE
 Standard?:
No
 BEP Mode:
VF
On-Chip Summing?:
No
 Row Sum:

 Column Sum:

 Frame Time:
Subarray Mode:
NONE
 Starting Row:
0
 Row Count:
1023
 Subarray Frame Time:

Duty Cycle?:
No
 Cycle Count:
0
 Primary Exp Time:

 Secondary Exp Time:
Event Filter?:
No
 Filter Threshold:

 Filter Range:

 Bias Requested?:
No
 Bias Frequency:

 Bias After?:
No
 Spatial Window?:
No

Abstract:
The distribution of jet angles for short gamma-ray bursts (SGRBs) is critical to constrain as it directly affects the true energy scale and event rate. The event rate is of particular interest in the gravitational wave era. Our current knowledge of the jet angle distribution comes almost exclusively from X-ray observations at >1 day after the burst. Here, we propose for a Chandra TOO observation to continue to monitor the afterglow of SGRB 210726A and constrain its collimation, either from the detection of the X-ray afterglow, which places a lower limit on the opening angle at >35 deg, or a non-detection of the afterglow, indicating a jet break has occurred and constraining the jet break to 13-35 deg. We have broad-band afterglow observations, which will be leveraged to provide the tightest constraints on the jet angle. This would be the first detection of a cosmological SGRB afterglow at >50 days, complementing the longest lasting detections of an SGRB radio afterglow.

Remarks:
We are requesting a medium response TOO because the source just became observable recently but will fade beyond the Chandra limit in 1 month.

psci Run:
187
 Processing Date:
Jan 17 2022
 psci Directory:
/nfs/maaxnew/r3/fd/acis118d/acis118.log
OBSID:
26247
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
402356
 Target Name:
SGRB_210726A
 AO:
22
Start VCDU:
99452:064
 Start Time (UTC):
365:68919.298
 Stop Time (UTC):
001:19285.122
 Kilosecs:
36.8
 % Frames:
100.0
 # CCDs:
S1
# Frames:
12090
 # Events:
351191
 Events/sec:
0
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-116.7
Parameter Block:
0x00914014
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te5x5
 BEP Mode:
F
 Start Row:
0
 # Rows:
1024
Primary Exposure:
30
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
Yes
 Bias Run:
187

pgf@space.mit.edu Mon Mar 31 10:36:39 EST 2025