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0. Table of contents

Last Updated 11 May 2021

1.  Timing Calibrations of X-ray missions

1.1 Summary of Timing Requirement and Calibrations

 

 

Mission/InstrumentsScience Requirement Absolute TimeTiming System DesignTiming Calibration StatusIn-orbit Timing
Calibration Targets		Reported IssuesReference
RequirementGoalGPS ReceiverClock StabilityOffsetDeviation, sigmaNotes
RXTE/PCA (star)10μsec noneNo
 		< 3.4 μsec3.4 μsecSpline-based calibration against ground timing standards

PSR B1821-24 60 μsec

Before 1997-04-29, increased timing jitter 8 μsec

rxte_time.html

Timing Budget
Jahoda et al. 2006 (10.1086/500659)

PSR B1821
Rots et al. 1998
(10.1086/305836)

Crab
Rots et al. 2001
(10.1086/420842)

RXTE/HEXTE(star)μsec none   delay 0-1 μsec (corrected?)Nonesee above
Chandra/ACIS0.25625 s
(one minor
frame start time)		0.001 s
(synchronize
minor frame starts)		No
(sync DSN)		3.2 μsec285 ± 6 μsec   None at presentDavis et al. 2003
(davis.pdf)
Chandra/HRC 16 μsec4 ± 4 μsec  Crab
PSR B1821-24

Note: Precision relative to RXTE.

Due to a wiring problem, photon time tag gets attached
to next event; correctable
under special mode for
HRC-S which telemeters
all events and then
reassigns times on the
ground.

Davis et al. 2003
(davis.pdf)

Rots 2006
(CXOClock.pdf)

XMM-Newton/EPIC-MOS          
XMM-Newtion/EPIC-PN1 msnoneNo-

-354±11 μsec

108 μsec ( 1 sigma)Note: Timing = -306 +/- 16, Burst  = -387+/-13.
Timing mode is affected by pile up.		Crab pulsar (bi-annual)None currently

Kirsch et al, SPIE, 5165, 85
(10.1117/12.503559)

Martin-Carrillo et al, A&A, 545, A126 (2012)
(10.1051/0004-6361/201116576)

CAL-TN-0220-1-4.pdf (Limited access)

INTEGRAL/SPI         

L.Kuiper 2003
(10.1051/0004-6361:20031353)

L.Kuiper 2019
(13th IACHEC PDF)


INTEGRAL/IBIS    -248±2 μsec61 μsecOffset is w.r.t. radio main-pulse using ISGRI 20-100 keV data collected during INTEGRAL Revolutions 47 - 1877
(last date Oct. 23, 2017); Jodrell Bank radio eph. folding		  same above
Swift/BAT~ 0.3 msGRB light curvesYes~ 6.572 x 10^-8 s/s~ 80 μs~ 100 μs  Crab pulsar (anual)None at presentBAT team wiki page;
private communication
with Michael Tripicco
see BAT Wiki: Pre-launch Timing,
BAT Wiki (410.4-SPEC-0005F.pdf)
(Limited Access)
Swift/XRT~ 10 ms ~ 270 μs Crab pulsar None at present

G. Cusumano et al 2012
(10.1051/0004-6361/201219968)

D. Burrows et al. 2005
(10.1007/s11214-005-5097-2)

Suzaku/XIS(star)

No science requirement defined.No
(sync. ground)

1.9 x 10^-9 s/s
(measured)

Not confirmed.N/A A0535+262, Her X-1, etcN/A
Y.Terada et al 2008
(10.1093/pasj/60.sp1.S25)
Suzaku/HXD(star)

~ 70 μsec

 

360±150 μsec (90%)

(270±130  μsec 
in condition)

“offset” is defined from the difference from
the average arrival time of Crab among X-ray missions
and the HXD in the simultaneous observation of Crab.		Crab for coordinated
PSR1509-58		Timing shift by a failure
in time stamp at the
ground station during
2012-2014
(Shu Koyama, Fixed)
NuSTAR/FPMShould be 100 msnoneNo

Freely drifting by ~3 ms/day.
Reduced to 20 us/day using
the clock correction file

 65 μs (1-sigma) 

Crab
B1821-24A
B1937+21

~5ms offset using
millisecond pulsars
(Lucien Kuiper)

Corrected through
clock correction file
v108+

Bachetti+ in prep
(can distribute early copy) 
Fermi/LAT   -111 ±4µs 57 µs 9 years of LAT data; see also Sci. 334, 69 (2011) for 9 months after launch value of -138 us +/- 12 us +/- 21 us; Jodrell Bank radio eph. folding   
Fermi/GBM (BGO)   -222 ±4µs 56 µs

100-300 keV band; data from Nov-2012 up to incl. Jan-2018; Jodrell Bank radio eph. folding

   
Fermi/GBM (NaI)         
AstroSat/LAXPCNone definedYes
(offline referral)		4 μsec rms
after GPS synchronization

-316 ±70µs

118 µs (rms)The offset is with respect to Fermi-LAT ephemerisCrab Pulsar
(with Radio) 		None at present

D. Bhattacharya 2017 (10.1007/s12036-017-9461-x)

Basu et al (in prep)

AstroSat/CZTINone definedYes
(offline referral)		3  μsec rms
after GPS synchronization		-650 ±70µs 83 µs (rms)The offset is with respect to Fermi-LAT ephemeris

Crab Pulsar
(with Radio) 

GRBs

None at present

D. Bhattacharya 2017 (10.1007/s12036-017-9461-x)

Basu et al 2018
(10.1051/0004-6361/201832913)

Basu et al (in prep)

HXMT          
Hitomi/SXS, SXI, HXI, SGD(star)350 μsec
35 μsecYes

0.01μsec(GPSR)
<3.0 μsec(SpW)
0.3 ns (orbit)

~ 120-230 μsec

<3.0 usec (3 sigma) Crab (with radio)
note: using out-of-time
event for SXI		absolute timing
accuracy is much
larger than expected
on ground (3 μsec)		Y.Terada et al 2018
(10.1117/1.JATIS.4.1.011206)
NICER/XTI100 ns (RMS)noneYesN/AApprox <3 us
[from wiki, but adding < mark here]		100 ns (RMS) [requirement] These values depend on the definition of absolute timing.
See supplementary material of this paper(https://science.sciencemag.org/content/372/6538/187),
Figure S12 and S13 [p.33-34] for the NICER Crab X-ray
main peak monitoring.
At this stage, it is not clear whether the fluctuation
of the peak phase is due to the instrumental effects
or due to intrinsic of the pulsar.		Crab Pulsar
PSR B1821-24A
PSR B1937+21		Precise 1-second offset
in on-board timestamps
due to flight software bug;
corrected using TIMEZERO
keyword in pipeline-processed
FITS data files.
(see HEASARC page for detail)		Markwardt  et al. (in prep.)
eROSITA          
XRISM/Resolve (blue star)1 msecnoneYessame as Hitomi

<1 ms <1 ms the values (1 msec) are the requirement including both offset and deviation.(under discussion)  
XRISM/Xtend (blue star)10 msecnoneYes< 10 ms< 10 ms the mission requirement values.(under discussion)  

(star) Mission completed.

(blue star) Future Mission

 

1.2 Point of Contacts

MissionPoC
RXTECraig Markwardt, Arnold Rots
ChandraVinay Kashyap, Arnold Rots
XMM-NewtonFelix Fuerst, Simon Rosen
SwiftAmy Lien
INTEGRALGuillaume Belanger, Volodymyr SAVCHENKO,Lucien Kuiper
NuSTARMatteo Bachetti, Katja Pottschmidt
Astrosat

Gulab Dewangan, Dipankar Bhattacharya

HXMTXiaobo LI
NICERCraig Markwardt, Teruaki Enoto
eROSITAto be confirmed
SuzakuYukikatsu Terada
HitomomiYukikatsu Terada
XRISMYukikatsu Terada

 

 

2. In-orbit Timing Calibration Plan/Observations

2.1 Archive Data

2.1.1 List of Coordinated Observations useful for Timing
2.1.2 Reports

2.2 New Coordinated Observations

 

 

3. Studies on Timing

3.1 effects on timing products (power spec, light curve etc) by the detector’s behavior (dead time, grade selection of calorimeter etc)

 

 

4. Timing Tools, (with Statistic Group)

 

 

5. Notes

 

 

 

 

 

 

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