C H A N D R A   S C I E N C E   C E N T E R
O B S E R V A T I O N   C A T A L O G

OBSID:
25553
 Title:
A Systematic Survey of Extreme X-ray Variability of Weak-Line Quasars  
Investigator:
Brandt
 Observer:
Brandt, William
 Phone:
814-865-3509
 Email:
wnbrandt@gmail.com
Target Name:
SDSS J095023.20+024651.7
 Sequence Number:
704534
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_005C6B
 Raster Scan:
N
 Annotated DOT:
FEB2122a

Proposal Number:
23700162
 Right Ascension:
147.597
 Declination:
2.78103
 Status:
archived
 Start Date:
2022-02-25 12:32:45
Category:
ACTIVE GALAXIES AND QUASARS
 Type:
GO
 AO Cycle:
23
 Dither Flag:
Y
 Y Offset:
0
 Z Offset:
0
Est. Count Rate:
0.0008
 Order-1 Count Rate:

 Exposure Time:
4
 Time Remaining:
4.112
 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:
S2 S4
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:
X-ray observations of weak-line quasars (WLQs) suggest that, among luminous quasars, they may preferentially show extreme large-amplitude X-ray variability events, perhaps due to variations in the height of a thick inner accretion disk. We thus propose a three-cycle Chandra program to monitor 10 luminous WLQs with the main aim of exploring such extreme X-ray variability events systematically. We will determine robustly if WLQs indeed more frequently show large-amplitude X-ray variability than typical quasars. The Chandra observations, combined with supporting HET spectra of rest-frame UV line/continuum emission, will also test if extreme X-ray variability events are best described by the thick inner-disk model, constraining the size of variations of inner-disk height.

Remarks:
We request one Chandra observation per cycle. We increase exposure times in subsequent cycles by 10% to allow for the expected degradation in full-band efficiency. As described in the proposal text, near-simultaneous supporting spectroscopy will be obtained with the queue-scheduled Hobby-Eberly Telescope (HET) - no Chandra time constraint is needed for this HET support.

psci Run:
52
 Processing Date:
Mar 3 2022
 psci Directory:
/nfs/maaxnew/r3/fe/acis119a/acis119.log
OBSID:
25553
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
704534
 Target Name:
SDSS_J095023.20
 AO:
23
Start VCDU:
115187:040
 Start Time (UTC):
056:46063.423
 Stop Time (UTC):
056:50187.573
 Kilosecs:
4.1
 % Frames:
100.0
 # CCDs:
S3
# Frames:
1313
 # Events:
103931
 Events/sec:
25
 PSCI errors:
0
 % drops:
0.1
 Bias Errs:
0
 FP Temp:
-117.5
Parameter Block:
0x005c6024
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te5x5
 BEP Mode:
F
 Start Row:
0
 # Rows:
1024
Primary Exposure:
31
 Secondary Exposure:
0
 Duty Cycle:
0
 Summing?:
No
 Bias?:
Yes
 Trickle?:
Yes
 Bias Run:
52

pgf@space.mit.edu Sat Mar 29 10:37:19 EST 2025