Recent Changes - Search:

edit SideBar

Introduction

Chapter 1: Introduction, installation and basic tempo2 usage

1.1 Introduction

Tempo2 is a new version of the pulsar timing software. An overview of the software is provided in Hobbs, Edwards & Manchester (2006). A second paper provides mathematical details of the algorithms used in the software (Edwards, Hobbs & Manchester (2006)). A third paper is in preparation and will describe how tempo2 can be used to simulate the effects of gravitational waves on pulsar timing residuals. A summary of tempo2's basic features can also be found in Hobbs, Edwards & Manchester (in press CHJAA).

1.2 Obtaining and installing tempo2

The tempo2 software and documentation can be obtained from this wiki (http://www.atnf.csiro.au/research/pulsar/tempo2). Click on the "Download tempo2" option to download the software to your local machine. This software requires compilation before it will run. Up-to-date installation instructions are available from the download section on this site and also in a README file available with the download. Note: tempo2 makes heavy use of "long double" precision in its calculations. Most compiler/architecture combinations support long doubles of 80 or 128 bits in size, which is sufficient. Tempo2 has been successfully tested under Linux-gcc/x86, Solaris/SPARC and Mac OS 10.4-gcc/PowerPC. Unfortunately, some systems only provide 64-bit long doubles (i.e. identical to a standard "double"); these include Mac OS 10.3.9 and earlier and many Windows compilers. Tempo2 will not install correctly on such machines.

1.3 A simple example of using tempo2

The tempo2 download page provides a set of example files for use to test the software. psr1.par contains the catalogued parameters for PSR J0437-4715 in standard tempo2 format. psr1.tim contains a set of simulated observations of this pulsar over a 10yr period with an rms residual of 100 ns. Running

 tempo2 -f psr1.par psr1.tim

should first provide some information about clock correction files and also:

 Results for PSR J0437-4715


 RMS pre-fit residual = 0.096 (us), RMS post-fit residual = 0.096 (us)
 Number of points in fit = 367


 PARAMETER       Pre-fit                   Post-fit                  Uncertainty   Difference   Fit
 ---------------------------------------------------------------------------------------------------
 RAJ (rad)       1.20978853473707          1.20978853473707          0             0             N
 RAJ (hms)       04:37:15.7865145          04:37:15.7865145          0             0            
 DECJ (rad)      -0.824709094464799        -0.824709094464799        0             0             N
 DECJ (dms)      -47:15:08.46158           -47:15:08.46158           0             0            
 F0 (s^-1)       173.687946306032          173.687946306032          0             0             N
 F1 (s^-2)       -1.7283139464043e-15      -1.7283139464043e-15      0             0             N
 PEPOCH (MJD)    51194.0001248168          51194.0001248168          0             0             N
 POSEPOCH (MJD)  51194.0001248168          51194.0001248168          0             0             N
 DMEPOCH (MJD)   51194                     51194                     0             0             N
 DM (cm^-3 pc)   2.64690012312213          2.64690012312213          0             0             N
 PMRA (mas/yr)   121.43799811708           121.43799811708           0             0             N
 PMDEC (mas/yr)  -71.4379988923397         -71.4379988923397         0             0             N
 PX (mas)        7.19                      7.19                      0             0             N
 SINI            0.6788                    0.6788                    0             0             N
 PB (d)          5.74104608901605          5.74104608901605          0             0             N
 T0 (MJD)        51194.6240248265          51194.6240248265          0             0             N
 A1 (lt-s)       3.36669162220122          3.36669162220122          0             0             N
 OM (deg)        1.2                       1.2                       0             0             N
 ECC             1.9186e-05                1.9186e-05                0             0             N
 PBDOT (10^-12)  3.64                      3.64                      0             0             N
 OMDOT (deg/yr)  0.0159999997519168        0.0159999997519168        0             0             N
 M2              0.236                     0.236                     0             0             N
 START (MJD)     50640.9281162413          49350.5129309451          0             -1290.4       N
 FINISH (MJD)    52088.8971386924          53000.5197060478          0             911.62        N
 TRACK (MJD)     0                         0                         0             0             N
 TZRMJD          51204.6438924841          51204.6438924841          0             0             N
 TZRFRQ (MHz)    1413.39997808495          1413.39997808495          0             0             N
 ---------------------------------------------------------------------------------------------------
 Binary model: DD
 Mass function                  = 0.001243113190  +- 0.000000000000 solar masses 
 Minimum companion mass         = 0.1403 solar masses
 Median companion mass          = 0.1637 solar masses
 Maximum companion mass         = 0.3493 solar masses
 MTOT derived from sin i and m2 = 1.8186068413766
 Inclination angle (deg)        = 42.74994182955 (+ 0 - 0)

Approximately 4 lines of extra output may be produced with the newest versions of tempo2, but this is the gist of it.

A second parameter file, psr1_2.par, is similar to psr1.par used above, except that the parameter values have been changed slightly from their true values. As above, running

 tempo2 -f psr1_2.par psr1.tim

should produce

 Results for PSR J0437-4715


 RMS pre-fit residual = 6.895 (us), RMS post-fit residual = 0.096 (us)
 Number of points in fit = 367


 PARAMETER       Pre-fit                   Post-fit                  Uncertainty   Difference   Fit
 ---------------------------------------------------------------------------------------------------
 RAJ (rad)       1.2097885336826           1.20978853474746          2.1206e-11    1.0649e-09    Y
 RAJ (hms)       04:37:15.7865              04:37:15.7865146         2.916e-07     1.4643e-05   
 DECJ (rad)      -0.824709094076948        -0.824709094473468        1.5157e-11    -3.9652e-10   Y
 DECJ (dms)      -47:15:08.4615            -47:15:08.46158           3.1264e-06    -8.1788e-05  
 F0 (s^-1)       173.68794630603           173.687946306032          9.5579e-15    2.3306e-12    Y
 F1 (s^-2)       -1.728e-15                -1.72831367406148e-15     2.3325e-22    -3.1367e-19   Y
 PEPOCH (MJD)    51194.0001248168          51194.0001248168          0             0             N
 POSEPOCH (MJD)  51194.0001248168          51194.0001248168          0             0             N
 DMEPOCH (MJD)   51194                     51194                     0             0             N
 DM (cm^-3 pc)   2.64690012312213          2.64690012312213          0             0             N
 PMRA (mas/yr)   121.43799811708           121.43799811708           0             0             N
 PMDEC (mas/yr)  -71.4379988923397         -71.4379988923397         0             0             N
 PX (mas)        7.19                      7.19                      0             0             N
 SINI            0.6788                    0.6788                    0             0             N
 PB (d)          5.741046089               5.74104608900813          1.0437e-11    8.1286e-12    Y
 T0 (MJD)        51194.6240248265          51194.6240248265          0             0             N
 A1 (lt-s)       3.36669162220122          3.36669162220122          0             0             N
 OM (deg)        1.2                       1.2                       0             0             N
 ECC             1.9186e-05                1.9186e-05                0             0             N
 PBDOT (10^-12)  3.64                      3.64                      0             0             N
 OMDOT (deg/yr)  0.0159999997519168        0.0159999997519168        0             0             N
 M2              0.236                     0.236                     0             0             N
 START (MJD)     50640.9281162413          49350.5129309451          0             -1290.4       N
 FINISH (MJD)    52088.8971386924          53000.5197060478          0             911.62        N
 TRACK (MJD)     0                         0                         0             0             N
 TZRMJD          51204.6438924841          51204.6438924841          0             0             N
 TZRFRQ (MHz)    1413.39997808495          1413.39997808495          0             0             N
 ---------------------------------------------------------------------------------------------------
 Binary model: DD
 Mass function                  = 0.001243113190  +- 0.000000047151 solar masses 
 Minimum companion mass         = 0.1403 solar masses
 Median companion mass          = 0.1637 solar masses
 Maximum companion mass         = 0.3493 solar masses
 MTOT derived from sin i and m2 = 1.818606841374
 Inclination angle (deg)        = 42.74994182955 (+ 0 - 0) 

The residuals can be inspected using

 tempo2 -gr plk -f psr1_2.par psr1.tim

which should produce a plot of the pre-fit residuals as shown in Figure 1.1a. Pressing '2' on the plot will show the post-fit residuals (Figure 1.1b)

Figure 1.1: a) pre-fit timing residuals for the test data-set and b) post-fit timing residuals.


Edit - History - Print - Recent Changes - Search
Page last modified on June 25, 2007, at 03:53 PM