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OBSID:
22592
 Title:
Chandra and Gravity observations of Sgr A* to constrain the motion of the NIR source during X-ray flares
Investigator:
Ponti
 Observer:
Ponti, Gabriele
 Phone:
+39272320425
 Email:
gabriele.ponti@inaf.it
Target Name:
Sgr A*
 Sequence Number:
703978
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_00C2CB
 Raster Scan:
N
 Annotated DOT:
MAY1721a

Proposal Number:
21700382
 Right Ascension:
266.417
 Declination:
-29.0078
 Status:
archived
 Start Date:
2021-05-23 01:46:20
Category:
ACTIVE GALAXIES AND QUASARS
 Type:
GO
 AO Cycle:
21
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
0.006
 Order-1 Count Rate:

 Exposure Time:
21.6
 Time Remaining:
21.523
 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
 Dropped Chip Count:
0
 Optional Chips:
S2 S4
On-Chip Summing?:
No
 Row Sum:

 Column Sum:

 Frame Time:
Subarray Mode:
CUSTOM
 Starting Row:
449
 Row Count:
128
 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:
We propose a 7*21.6ks Chandra monitoring campaign to cover 7 nights of VLTI-Gravity guaranteed time observations of SgrA*, during the summer of 2020. Our Gravity team has already measured the astrometric motion of the near infrared (NIR) source during bright NIR flux excursions. In particular, we observed in 3 occasions that the NIR source was located at few gravitational radii from the supermassive black hole and rotating, following nearly circular orbits. Simultaneous Chandra+Gravity observations will allow us to test whether, during X-ray flares, the NIR source will display similar circular orbital motions or whether it will be characterised by a dramatically different pattern, such as by linear motion, reminiscent of jet like ejections.

Remarks:
The 7*21.6ks Chandra observations shall overlap, as much as possible, with 14 nights of Gravity guaranteed time observations. SgrA* will be visible by Gravity from more than 6hr from 2020-05-05 until 2020-06-08 and from 2020-06-27 until 2020-07-25. The Gravity observations will occur in two blocks of one week (7 consecutive nights) each, around full moon. Most likely periods are: May 5th to 12th and July 1st to 8th. Given the Chandra orbit and the radiation belt passage, Chandra should be able to cover 4-5 nights each week. We request the coverage of 7 nights of Gravity observations.

psci Run:
282
 Processing Date:
Jun 4 2021
 psci Directory:
/nfs/maaxnew/r3/fa/acis115e/acis115.log
OBSID:
22592
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
703978
 Target Name:
Sgr_A*
 AO:
21
Start VCDU:
37093:000
 Start Time (UTC):
143:07640.809
 Stop Time (UTC):
143:29167.540
 Kilosecs:
21.5
 % Frames:
100.0
 # CCDs:
S3
# Frames:
33581
 # Events:
111170
 Events/sec:
5
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-117.5
Parameter Block:
0x00c2c014
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te3x3
 BEP Mode:
F
 Start Row:
448
 # Rows:
128
Primary Exposure:
6
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
Yes
 Bias Run:
282

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