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OBSID:
23491
 Title:
Searching for transient propeller-phase neutron star ULXs    
Investigator:
Earnshaw
 Observer:
Earnshaw, Hannah
 Phone:
626-395-1708
 Email:
hpearn@caltech.edu
Target Name:
NGC 4485/90
 Sequence Number:
402269
 Instrument:
ACIS-S
 Grating:
NONE
 SI Mode:
TE_007BCB
 Raster Scan:
N
 Annotated DOT:
AUG0221a

Proposal Number:
22400554
 Right Ascension:
187.646
 Declination:
41.6639
 Status:
archived
 Start Date:
2021-08-06 15:22:42
Category:
BH AND NS BINARIES
 Type:
GO
 AO Cycle:
22
 Dither Flag:
Y
 Y Offset:
-2.4
 Z Offset:
0
Est. Count Rate:
0.05
 Order-1 Count Rate:

 Exposure Time:
30
 Time Remaining:
30.054
 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:
1
 Optional Chips:
I2 I3 S1 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:
An open question in the study of ultraluminous X-ray sources (ULXs) is how many of the population may be super-Eddington accreting neutron stars (NSs). One method of finding candidate NSs in the ULX population is to search for sources that demonstrate a distinctive bimodal flux distribution over multiple observations resulting from the intermittent onset of the 'propeller effect', in which accretion is halted at the magnetospheric radius. We propose 10 observations each of 3 ULX-rich galaxies in order to identify the ULXs that exhibit flux bimodality from a sample of >= 25 ULXs. This will allow us to better characterise this class of source, including quantifying their duty cycles and beginning to place observational limits on the proportion of the ULX population that is made up of NSs.

psci Run:
231
 Processing Date:
Aug 11 2021
 psci Directory:
/nfs/maaxnew/r3/fb/acis116d/acis116.log
OBSID:
23491
 SIM Mode:
ACIS-S
 OTG Mode:
NONE
 Seq Number:
402269
 Target Name:
NGC_4485/90
 AO:
22
Start VCDU:
105046:072
 Start Time (UTC):
218:56258.980
 Stop Time (UTC):
218:86327.792
 Kilosecs:
30.1
 % Frames:
100.0
 # CCDs:
I5
# Frames:
9573
 # Events:
1251395
 Events/sec:
41
 PSCI errors:
0
 % drops:
0.0
 Bias Errs:
2
 FP Temp:
-118.1
Parameter Block:
0x007bc024
 Window Block:
-
 # Windows:
0
 FEP Mode:
Te3x3
 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:
231

pgf@space.mit.edu Thu Apr 3 20:00:53 EST 2025