Timing accuracy of the Swift X-Ray Telescope in WT mode

G. Cusumano, V. La Parola, M. Capalbi, M. Perri, A. P. Beardmore, D. N. Burrows, S. Campana, J. A. Kennea, J. P. Osborne, B. Sbarufatti, G. Tagliaferri

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Context. The X-Ray Telescope (XRT) on board Swift was mainly designed to provide detailed position, timing and spectroscopic information on gamma-ray burst (GRB) afterglows. During the mission lifetime the fraction of observing time allocated to other types of source has been steadily increased. Aims. In this paper, we report on the results of the in-flight calibration of the timing capabilities of the XRT in Windowed Timing read-out mode. Methods. We use observations of the Crab pulsar to evaluate the accuracy of the pulse period determination by comparing the values obtained by the XRT timing analysis with the values derived from radio monitoring. We also check the absolute time reconstruction measuring the phase position of the main peak in the Crab profile and comparing it both with the value reported in literature and with the result that we obtain from a simultaneous Rossi X-Ray Timing Explorer (RXTE) observation. Results. We find that the accuracy in period determination for the Crab pulsar is of the order of a few picoseconds for the observation with the largest data time span. The absolute time reconstruction, measured using the position of the Crab main peak, shows that the main peak anticipates the phase of the position reported in literature for RXTE by ∼270 μs on average (∼150 μs when data are reduced with the attitude file corrected with the UVOT data). The analysis of the simultaneous Swift-XRT and RXTE proportional counter array (PCA) observations confirms that the XRT Crab profile leads the PCA profile by ∼200 μs. The analysis of XRT photodiode mode data and BAT event data shows a main peak position in good agreement with the RXTE, suggesting the discrepancy observed in XRT data in Windowed Timing mode is likely due to a systematic offset in the time assignment for this XRT read out mode.

Original languageEnglish (US)
Article numberA28
JournalAstronomy and Astrophysics
Volume548
DOIs
StatePublished - Nov 22 2012

Fingerprint

crabs
time measurement
telescopes
X Ray Timing Explorer
x rays
crab
proportional counters
pulsars
profiles
afterglows
files
gamma ray bursts
photodiodes
flight
life (durability)
pulses
radio
calibration
monitoring

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Cusumano, G., La Parola, V., Capalbi, M., Perri, M., Beardmore, A. P., Burrows, D. N., ... Tagliaferri, G. (2012). Timing accuracy of the Swift X-Ray Telescope in WT mode. Astronomy and Astrophysics, 548, [A28]. https://doi.org/10.1051/0004-6361/201219968
Cusumano, G. ; La Parola, V. ; Capalbi, M. ; Perri, M. ; Beardmore, A. P. ; Burrows, D. N. ; Campana, S. ; Kennea, J. A. ; Osborne, J. P. ; Sbarufatti, B. ; Tagliaferri, G. / Timing accuracy of the Swift X-Ray Telescope in WT mode. In: Astronomy and Astrophysics. 2012 ; Vol. 548.
@article{a6028d6b52e5433ca328d6609660b298,
title = "Timing accuracy of the Swift X-Ray Telescope in WT mode",
abstract = "Context. The X-Ray Telescope (XRT) on board Swift was mainly designed to provide detailed position, timing and spectroscopic information on gamma-ray burst (GRB) afterglows. During the mission lifetime the fraction of observing time allocated to other types of source has been steadily increased. Aims. In this paper, we report on the results of the in-flight calibration of the timing capabilities of the XRT in Windowed Timing read-out mode. Methods. We use observations of the Crab pulsar to evaluate the accuracy of the pulse period determination by comparing the values obtained by the XRT timing analysis with the values derived from radio monitoring. We also check the absolute time reconstruction measuring the phase position of the main peak in the Crab profile and comparing it both with the value reported in literature and with the result that we obtain from a simultaneous Rossi X-Ray Timing Explorer (RXTE) observation. Results. We find that the accuracy in period determination for the Crab pulsar is of the order of a few picoseconds for the observation with the largest data time span. The absolute time reconstruction, measured using the position of the Crab main peak, shows that the main peak anticipates the phase of the position reported in literature for RXTE by ∼270 μs on average (∼150 μs when data are reduced with the attitude file corrected with the UVOT data). The analysis of the simultaneous Swift-XRT and RXTE proportional counter array (PCA) observations confirms that the XRT Crab profile leads the PCA profile by ∼200 μs. The analysis of XRT photodiode mode data and BAT event data shows a main peak position in good agreement with the RXTE, suggesting the discrepancy observed in XRT data in Windowed Timing mode is likely due to a systematic offset in the time assignment for this XRT read out mode.",
author = "G. Cusumano and {La Parola}, V. and M. Capalbi and M. Perri and Beardmore, {A. P.} and Burrows, {D. N.} and S. Campana and Kennea, {J. A.} and Osborne, {J. P.} and B. Sbarufatti and G. Tagliaferri",
year = "2012",
month = "11",
day = "22",
doi = "10.1051/0004-6361/201219968",
language = "English (US)",
volume = "548",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

Cusumano, G, La Parola, V, Capalbi, M, Perri, M, Beardmore, AP, Burrows, DN, Campana, S, Kennea, JA, Osborne, JP, Sbarufatti, B & Tagliaferri, G 2012, 'Timing accuracy of the Swift X-Ray Telescope in WT mode', Astronomy and Astrophysics, vol. 548, A28. https://doi.org/10.1051/0004-6361/201219968

Timing accuracy of the Swift X-Ray Telescope in WT mode. / Cusumano, G.; La Parola, V.; Capalbi, M.; Perri, M.; Beardmore, A. P.; Burrows, D. N.; Campana, S.; Kennea, J. A.; Osborne, J. P.; Sbarufatti, B.; Tagliaferri, G.

In: Astronomy and Astrophysics, Vol. 548, A28, 22.11.2012.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Timing accuracy of the Swift X-Ray Telescope in WT mode

AU - Cusumano, G.

AU - La Parola, V.

AU - Capalbi, M.

AU - Perri, M.

AU - Beardmore, A. P.

AU - Burrows, D. N.

AU - Campana, S.

AU - Kennea, J. A.

AU - Osborne, J. P.

AU - Sbarufatti, B.

AU - Tagliaferri, G.

PY - 2012/11/22

Y1 - 2012/11/22

N2 - Context. The X-Ray Telescope (XRT) on board Swift was mainly designed to provide detailed position, timing and spectroscopic information on gamma-ray burst (GRB) afterglows. During the mission lifetime the fraction of observing time allocated to other types of source has been steadily increased. Aims. In this paper, we report on the results of the in-flight calibration of the timing capabilities of the XRT in Windowed Timing read-out mode. Methods. We use observations of the Crab pulsar to evaluate the accuracy of the pulse period determination by comparing the values obtained by the XRT timing analysis with the values derived from radio monitoring. We also check the absolute time reconstruction measuring the phase position of the main peak in the Crab profile and comparing it both with the value reported in literature and with the result that we obtain from a simultaneous Rossi X-Ray Timing Explorer (RXTE) observation. Results. We find that the accuracy in period determination for the Crab pulsar is of the order of a few picoseconds for the observation with the largest data time span. The absolute time reconstruction, measured using the position of the Crab main peak, shows that the main peak anticipates the phase of the position reported in literature for RXTE by ∼270 μs on average (∼150 μs when data are reduced with the attitude file corrected with the UVOT data). The analysis of the simultaneous Swift-XRT and RXTE proportional counter array (PCA) observations confirms that the XRT Crab profile leads the PCA profile by ∼200 μs. The analysis of XRT photodiode mode data and BAT event data shows a main peak position in good agreement with the RXTE, suggesting the discrepancy observed in XRT data in Windowed Timing mode is likely due to a systematic offset in the time assignment for this XRT read out mode.

AB - Context. The X-Ray Telescope (XRT) on board Swift was mainly designed to provide detailed position, timing and spectroscopic information on gamma-ray burst (GRB) afterglows. During the mission lifetime the fraction of observing time allocated to other types of source has been steadily increased. Aims. In this paper, we report on the results of the in-flight calibration of the timing capabilities of the XRT in Windowed Timing read-out mode. Methods. We use observations of the Crab pulsar to evaluate the accuracy of the pulse period determination by comparing the values obtained by the XRT timing analysis with the values derived from radio monitoring. We also check the absolute time reconstruction measuring the phase position of the main peak in the Crab profile and comparing it both with the value reported in literature and with the result that we obtain from a simultaneous Rossi X-Ray Timing Explorer (RXTE) observation. Results. We find that the accuracy in period determination for the Crab pulsar is of the order of a few picoseconds for the observation with the largest data time span. The absolute time reconstruction, measured using the position of the Crab main peak, shows that the main peak anticipates the phase of the position reported in literature for RXTE by ∼270 μs on average (∼150 μs when data are reduced with the attitude file corrected with the UVOT data). The analysis of the simultaneous Swift-XRT and RXTE proportional counter array (PCA) observations confirms that the XRT Crab profile leads the PCA profile by ∼200 μs. The analysis of XRT photodiode mode data and BAT event data shows a main peak position in good agreement with the RXTE, suggesting the discrepancy observed in XRT data in Windowed Timing mode is likely due to a systematic offset in the time assignment for this XRT read out mode.

UR - http://www.scopus.com/inward/record.url?scp=84869195383&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84869195383&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201219968

DO - 10.1051/0004-6361/201219968

M3 - Article

AN - SCOPUS:84869195383

VL - 548

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A28

ER -

Cusumano G, La Parola V, Capalbi M, Perri M, Beardmore AP, Burrows DN et al. Timing accuracy of the Swift X-Ray Telescope in WT mode. Astronomy and Astrophysics. 2012 Nov 22;548. A28. https://doi.org/10.1051/0004-6361/201219968