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OBSID:
27736
 Title:
Which Source is Active in Terzan 5?        
Investigator:
Heinke
 Observer:
Heinke, Craig
 Phone:
780-222-4815
 Email:
heinke@ualberta.ca
Target Name:
Terzan 5
 Sequence Number:
402457
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_00A88B
 Raster Scan:
N
 Annotated DOT:
MAR1723a

Proposal Number:
24408893
 Right Ascension:
267.021
 Declination:
-24.78
 Status:
archived
 Start Date:
2023-03-18 14:56:06
Category:
BH AND NS BINARIES
 Type:
DDT
 AO Cycle:
24
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
17
 Order-1 Count Rate:

 Exposure Time:
10
 Time Remaining:
11.097
 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:
F
On-Chip Summing?:
No
 Row Sum:

 Column Sum:

 Frame Time:
Subarray Mode:
CUSTOM
 Starting Row:
385
 Row Count:
256
 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:
Many globular clusters contain multiple transient LMXBs, identified by Chandra in e.g. NGC 6440, Liller 1, and Terzan 5. MAXI sees an outburst from Terzan 5 (Atel 15917, at 89 mCrab), confirmed by Swift (Atel 15919, Kennea+23), suggested to be Terzan 5 X-3, last seen in 2012. However, the Swift 3.5 error circle includes 5-6 other known X-ray sources, and the redback MSP Ter 5 P (Bogdanov+21)--possibly a transitional MSP (only 3 confirmed). We request Chandra to pinpoint the outbursting LMXB. If we confirm Ter 5 X-3, we will establish its recurrence time and thus average mass-transfer rate, crucial for studies of crust and core cooling (e.g. Brown+2018). If it is a new transient, it will enable e.g. a census of transient LMXBs, their recurrence rates, the quiescent spectrum, & enable later IR follow-up (e.g. 30-m class). Radio studies are proposed, but their angular resolution is less (VLA is in B-config) and Terzan 5 is very complex in the radio (Urquhart+2020), so Chandra is needed.

psci Run:
280
 Processing Date:
Apr 10 2023
 psci Directory:
/nfs/maaxnew/r3/fi/acis123e/acis123.log
OBSID:
27736
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
402457
 Target Name:
Terzan_5
 AO:
24
Start VCDU:
77674:024
 Start Time (UTC):
077:54551.236
 Stop Time (UTC):
077:65652.599
 Kilosecs:
11.1
 % Frames:
100.0
 # CCDs:
S2
# Frames:
11797
 # Events:
203521
 Events/sec:
18
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-112.8
Parameter Block:
0x00a88024
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te3x3
 BEP Mode:
F
 Start Row:
384
 # Rows:
256
Primary Exposure:
9
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
Yes
 Bias Run:
280

pgf@space.mit.edu Tue Apr 8 9:48:31 EST 2025