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OBSID:
25398
 Title:
The X-ray view of the unambiguous periodicity of ASASSN-14ko.    
Investigator:
Auchettl
 Observer:
Auchettl, Katie
 Phone:
9252975283
 Email:
kauchett@ucsc.edu
Target Name:
ASASSN-14ko
 Sequence Number:
704442
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_004A4B
 Raster Scan:
N
 Annotated DOT:
MAY3022b

Proposal Number:
23700492
 Right Ascension:
81.3255
 Declination:
-46.0056
 Status:
archived
 Start Date:
2022-05-31 12:08:52
Category:
ACTIVE GALAXIES AND QUASARS
 Type:
GO
 AO Cycle:
23
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
0.05
 Order-1 Count Rate:

 Exposure Time:
32
 Time Remaining:
30.752
 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
 Dropped Chip Count:
0
 Optional Chips:
I2 I3
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:
AGN variability is usually well described by a damped random walk. However, periodic or quasi-periodic signatures distinct from this stochastic variability have been long been sort after as they may indicate the presence of a binary supermassive black hole system or another unique mechanism such a repeating tidal disruption event. Recently, the first case of unambiguous optical periodicity with a period of ~114 days was discovered as ASASSN-14ko in the galaxy ESO 253-G003. The precise origin of these flares remains unknown, however the predictable nature of this flaring event provides a unique opportunity to probe the origin and evolution of these periodic flares. Here we propose to use Chandra to fully characterize the X-ray emission of a flare that occurs during Cycle 23.

Remarks:
The peak of the next optical flares that are expected to occur during Cycle 23 are 2022 February 24, 2022 June 10,2022 September 23 and 2023 January 6. We request 8 epochs totalling 154 ks that are spaced 5 days apart, starting 20 days before peak optical brightness. Here the corresponding exposures are: 5, 10, 50, 20, 10, 15, 34, 10 ks for -20, -15,-10,-5,0,+5,+10,+15 days relative to peak. We also note that the observation taken at -20 days will have a pile-up of 12%, while all other observations will 6% or less.

psci Run:
120
 Processing Date:
Jun 9 2022
 psci Directory:
/nfs/maaxnew/r3/ff/acis120b/acis120.log
OBSID:
25398
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
704442
 Target Name:
ASASSN-14ko
 AO:
23
Start VCDU:
103244:048
 Start Time (UTC):
151:45064.371
 Stop Time (UTC):
151:75828.226
 Kilosecs:
30.8
 % Frames:
100.0
 # CCDs:
I6
# Frames:
9492
 # Events:
1401866
 Events/sec:
45
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
0
 FP Temp:
-114.7
Parameter Block:
0x004a4034
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te5x5
 BEP Mode:
F
 Start Row:
0
 # Rows:
1024
Primary Exposure:
32
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
Yes
 Bias Run:
120

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