# README_3PC_TimingModels.txt # Created by david.smith@u-bordeaux.fr (=das) on 2023 February 15. # Update (das) 25 July 2023. It describes the collection of pulsar rotation ephemeris files provided with the Fermi LAT 3rd catalog of gamma-ray pulsars ("3PC") re-submitted to the Astrophysical Journal Supplement. The files are also called ".par files" or "pulsar timing models". All the .par files are compatible with the tempo2 timing software [1] and the PINT timing software [2], used to calculate the pulsar rotation phases stored in the LAT data files. These "FT1" files are described in a separate README file provided with the 3PC online material. These phases were used to create the phase histograms provided with the 3PC online material, as images or numerically, also described in the README files. Typical commands used to add a PULSE_PHASE column using these ephemerides are: # Using Tempo2 % tempo2 -gr fermi -ft1 XXX_FT1.fits -ft2 XXX_FT2.fits -phase -f J0653+4706.par # or using PINT % fermiphase --ft2 XXX_FT2.fits --addphase XXX_FT1.fits J0653+4706.par CALC Three typical file names help understand the file naming convention: J0117+5914_JBO.par J0248+6021_NRT_3.par J1946-5403_LAT_PKSTZR.par The first 10 to 11 characters are the pulsar name (right ascension and declination). The following set of three characters describes the observatory (see table, below) that provided most or all of the timing data used to create the ephemeris. A digit indicates that a single timing model does not accurately calculate rotation phases over the full epoch used (see "START, FINISH", below), and instead separate models were used for sub-epochs. LAT_PKSTZR means that the timing model was made using LAT gamma-ray timing, and that radio/gamma-ray phase alignment was obtained using radio observations (see "TZR", below). Table 4 in 3PC lists the radio observatories that provided pulsar timing for 3PC. Cite the references given in Table 4 if you use their ephemerides, as possible. Here follow the 2 to 4 character abbreviations: PKS Parkes JBO Jodrell Bank NRT Nancay GBT Green Bank Eff Effelsberg GMRT Giant Metrewave Radio Telescope AO Arecibo FAST Five hundred Meter Aperture Spherical Telescope MOL Molongolo LOF LOFAR MK MeerKAT FA FAST In addition, LAT indicates gamma-ray timing using Large Area Telescope data, and X-rays indicates that timing data came from (an) X-ray telescope(s). For timing updates, contact 3PC authors affiliated with the appropriate observatory ; or ask the 3PC contact authors to direct you to the appropriate scientists. Rotation ephemeris parameters come from fits of observed pulse arrival times to a timing model; unbinned profile optimisation; or similar methods. The START and FINISH parameters in the .par files correspond to the first and last arrival times, respectively. The epoch between START and FINISH is called the "validity interval". Many pulsars have stable spin and braking rates, described by simple models, that accurately predict rotational phase for months and years outside of the validity interval. Many other pulsars have "noisy" braking rates, requiring timing models with many parameters to fit the pulse arrival data. Phase predictions can become unreliable hours or days outside the validity interval -- See 3PC Figure 4. In consequence, if you use these .par files to phase pulsar data, we recommend plotting the pulse phase versus time, as in Figure 4, to make sure that no undesired drifting occurs. Aligning LAT gamma-ray pulses with those obtained with other instruments (radio, X-ray, etc) requires a phase reference applied to both data sets. The TZRSITE, TZRMJD, and TZRFRQ parameters allow such alignment. Tempo2 and PINT assign phase 0 to the first time-of-arrival (or first gamma photon) using the three TZR ("T zero", or reference time) parameters, as follows: TZRSITE names the observatory that obtained the reference pulse. The observatory names are similar to those in the table, above. PINT and Tempo2 files include the precise observatory coordinates, allowing a calculation of the propagation time between the solar system barycenter (SSB) and the observatory. Both codes translate all arrival times recorded at the observatory to the times the pulses would arrive at the SSB as a prerequisite to calculating rotational phase, necessary to compensate the Earth's motion. (The EPHEM parameter specifies the planetary ephemeris used to locate the SSB at a given time.) Radio pulse propagation times depend on the radio frequency. The TZRFRQ gives the reference frequency, in MHz. Note that the value of the dispersion measure (DM) affects radio pulse arrival times. A zero value for TZRFRQ indicates "infinite frequency", as for X- and gamma-ray derived timing models. TZRMJD (MJD = Modified Julian Day) is the arrival time of the reference pulse. Rotation ephemerides are NOT provided for the following pulsars, pending publication by their discoverers. Write to 3PC contact author Colin Clark for updated information. J0744-2525 J0802-5613 J0955-3947 J1139-6247 J1203-6242 J1231-5113 J1231-6511 J1259-8148 J1306-6043 J1311-3430 J1335-5656 J1358-6025 J1447-5757 J1623-6936 J1649-3012 J1736-3422 J1742-3321 J1745+1017 J1748-2815 J1757-6032 J1858-5422 J2029-4239 J2034+3632 J2115+5448 PSR J1846-0258 does not exhibit gamma-ray pulsations above 100 MeV like all of the others. Its signal is weak, and appears below 100 MeV. 3PC Section 7.2 provides details. [1] TEMPO2, a new pulsar-timing package - I. An overview Hobbs, G. B. ; Edwards, R. T. ; Manchester, R. N. arXiv: astro-ph/0603381 DOI: 10.1111/j.1365-2966.2006.10302.x http://adsabs.harvard.edu/abs/2006MNRAS.369..655H and the "fermi" plugin for Tempo2 is described here: Precise gamma-ray Timing and Radio Observations of 17 Fermi gamma-ray Pulsars Ray, P. S., Kerr, M., Parent, D., Abdo, A. A., Guillemot, L., Ransom, S. M., Rea, N., Wolff, M. T., Makeev, A., Roberts, M. S. E., Camilo, F., Dormody, M., Freire, P. C. C., Grove, J. E., Gwon, C., Harding, A. K., Johnston, S., Keith, M., Kramer, M., Michelson, P. F., Romani, R. W., Saz Parkinson, P. M., Thompson, D. J., Weltevrede, P., Wood, K. S., and Ziegler, M. arXiv:1011.2468 DOI: 10.1088/0067-0049/194/2/17 https://ui.adsabs.harvard.edu/abs/2011ApJS..194...17R/ [2] PINT: A Modern Software Package for Pulsar Timing Luo, Jing ; Ransom, Scott ; Demorest, Paul ; Ray, Paul S. ; Archibald, Anne ; Kerr, Matthew ; Jennings, Ross J. ; Bachetti, Matteo ; van Haasteren, Rutger ; Champagne, Chloe A. ; Colen, Jonathan ; Phillips, Camryn ; Zimmerman, Josef ; Stovall, Kevin ; Lam, Michael T. ; Jenet, Fredrick A., DOI: 10.3847/1538-4357/abe62f arXiv:2012.00074 https://ui.adsabs.harvard.edu/abs/2021ApJ...911...45L