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Pulsar Ephemerides for timing LAT Pulsars

Timing pulsars with the LAT requires the use of an ephemeris that covers the time period being analyzed. Below are several resources to provide this useful input to your analysis. These include:

• High E-dot Radio timing models — Provided by the Pulsar Timing Consortium.
• Ephemerides for Radio-faint or Radio-quiet LAT PUlsars — Provided by the LAT team.
• Pulsar Timing Models used in LAT Team Publications — Provided by the LAT team to allow replication of published analyses.
• Gamma-ray Ephemeris Database in D4 Format — For use with the Fermi Science Tools. Provided by the LAT team early in the mission for some pulsars. (Now obsolete)

Please remember that the collection and analysis of radio and LAT data that goes into generating each ephemeris is a significant time investment. Remember to acknowledge the source of the ephemeris and any appropriate references should you use any of these ephemerides for a publication. Please email the timing contact for the pulsar ephemeris you have used, or contact the Fermi helpdesk if you have any questions regarding this policy.

NOTE: Epoch folding pulsars with the Fermi Science Tools (e.g. using gtpphase and gtpsearch) requires use of a pulsar ephemeris database in the D4 FITS format (based on the EGRET pulsar analysis). An archive of these ephemerides is available for download at the bottom of this page. However, these ephemerides are quite out of date. We strongly recommend contacting the timing observers for the most current information about any pulsar.

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High E-dot Pulsar Radio Timing Models

Prior to the launch of Fermi, a group of radio and X-ray astronomers organized a "Fermi pulsar timing consortium" to provide rotation ephemerides for 224 pulsars known at that time to have spin-down power Edot > 10³⁴ erg/s. This campaign is described in Smith et. al, 2008 The consortium agreed to make their work publicly available after Fermi's first year in orbit, to allow phase-folding of gamma-ray pulsars and pulsar-candidates by scientists using data from the Large Area Telescope (LAT). The rotation ephemerides for 216 pulsars for which timing was obtained, in the form of TEMPO2 parameter files, are available here:

• HighEdot_ephems_v1.tar (Posted 2010 Dec 23)

Please take a moment to review the information in the README file before using the data for analysis or publication. Users are STRONGLY encouraged to contact the timing observers for the most current information about any pulsar.

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Pulsar Timing Models from LAT data

Some pulsars are radio quiet, or can be better timed using LAT data than radio data. For the most recent timing solutions for these pulsars, please go to the LAT Gamma-ray Pulsar Timing Models page, which is maintained by the LAT team.

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Pulsar Timing Models used in LAT Publications

The following table includes pulsar timing files used in publications of Fermi pulsars. The publication reference is given after the file listing. The radio template is provided when available.

Some pulsars have enough timing noise that phases for gamma rays can be better calculated by a more detailed timing model than is available in the D4 timing database. For such pulsars, analysis using the TEMPO or TEMPO2 radio timing systems is a better choice. An interface to these packages is under development. The TEMPO and TEMPO2 timing solutions are included in the table as .par files. For each pulsar, the preferred timing file is noted in the table in bold.

The rotation parameters are available in two file formats:

1. In a "D4 FITS" file, to be read by the Fermi LAT Science Tools, as discussed in Smith, Guillemot et al A&A 492, 923 (2008) (DOI:10.1051/0004-6361:200810285) and detailed in the FSSC documentation .
2. In TEMPO and TEMPO2 ".par" files.
   TEMPO is described at http://www.atnf.csiro.au/research/pulsar/tempo/ .
   TEMPO2 is described at http://www.atnf.csiro.au/research/pulsar/tempo2/ .
   The .par files are described at http://www.atnf.csiro.au/research/pulsar/tempo2/inde.php?n=Documentation.Parameters .

When using these timing solutions in a publication, please refer to the following reference(s), depending on the radio instrument(s) used to obtain them (given in the table below):

• GBT: details are given for each pulsar in the "Publication Reference" listed below
• Parkes: P. Weltevrede, et al., 2010, PASA, 27, 64
• Jodrell Bank: G. Hobbs, A.G. Lyne, M. Kramer, C.E. Martin, C. Jordan, 2004, MNRAS, 353, 1311
• Nançay: G. Theureau, N. Coudreau, N. Hallet, M. Hanski, L. Alsac, et al., 2005, A&A, 430, 373
• Arecibo: A. Dowd, W. Sisk, J. Hagen, 2000, ASC Conf. Ser., 202, 275
• Westerbork: J.L.L. Voûte, M.L.A. Kouwenhoven, P.C. van Haren, J.J. Langerak, B.W. Stappers, et al., 2002, A&A, 385, 733

Table of Published Ephemerides

Note: When using links in the table to send mail to contact authors or to radio contacts, please replace "at" with "@" and "dot" with "." in the email address before sending.

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Pulsar Timing Models in D4 Format - Obsolete

Epoch folding pulsars with the Fermi Science Tools (e.g. using gtpphase and gtpsearch) requires use of a pulsar ephemeris database in the D4 FITS format (based on the EGRET pulsar analysis). It is prudent to use the timing models provided for analysis only within the validity range specified within the file. The accuracy of the models may degrade rapidly outside that range, particularly for noisy pulsars. A single D4 FITS file containing timing information for the LAT pulsars to date is available here:

• Fermi_PulsarDB_v001.fits (Posted 2009 Aug 24)

NOTE: The pulsar ephemerides in the FSSC D4 database are provided as a courtesy by the original observers. Users are STRONGLY encouraged to contact the timing observers for the most current information about any pulsar.

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Last updated by: Elizabeth Ferrara 06/06/2011

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Last Modified: Mon, Aug 01, 2011