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OverviewTEMPO2: An overviewTempo2 is a new pulsar timing package. It was developed to be used both for general pulsar timing applications and also for pulsar timing array research in which data-sets from multiple pulsars need to be processed simultaneously. Tempo2 was initially developed by George Hobbs and Russell Edwards as part of the Parkes Pulsar Timing Array project. A summary of the features of tempo2 was published in Hobbs, Edwards & Manchester (2006). Full details of the timing model were published in Edwards, Hobbs & Manchester (2006). Tempo2 is now being used in pulsar timing research world-wide. It has been used in the analysis of PSR J1600-3053 (Ord et al. 2006), to limit the existence of gravitational waves (Jenet et al. 2006) and in studying pulsar dispersion measures (You et al. 2007). Tempo2 is based on the original tempo code and can be used (from the command-line) in a similar fashion. However, tempo2 is very versatile and can be extended by the creation of pieces of software called plug-ins. It is expected that many such plug-ins will be written and made available on this wiki. The plk plug-inThe plk interface provides a graphical interface to tempo2 that allows the user to identify, view and delete observations and to plot the pre- and post-fit residuals. This interface is called using, for example, tempo2 -gr plk -f mypar.par mypar.tim This should open a window containing the pulsar's pre-fit residuals and a menu bar. Moving the mouse cursor into the window and pressing 'h' will provide help information. The menu bar allows the user to change the fitted parameters, to redo the fit and to produce new parameter and arrival time files. Clicking on a residuals with the left mouse button identifies the observation, the middle mouse button calls the psrchive software to view the selected profile and the right mouse button deletes an observation.  Figure 1. Example of plotting post-fit residuals using the plk graphical interface. Green points represent 20cm observations, blue are 10cm observations and the red highlighted points are those obtained by the observer indicated by "GH". Note, the ability to add a label "(a)" and to add a vertical line (at 2004.6). The menu bar at the top allows the user to select different parameters to update in the fit (highlighted in red) and to redo the fit, create a new arrival time file and parameter file.  Figure 2. Example of plotting post-fit residuals using the plk graphical interface. In this figure the post-fit residuals are plotted versus the zenith angle of the observation.   Figure 3. The plk plugin can be used to show how the model parameters are updated between the pre-fit and post-fit residuals. For these plots the TOAs were simulated using the "fake" plugin. Output formatsBy default, tempo2 provides a simple output format such as: Results for PSR J1022+1001 RMS pre-fit residual = 5.551 (us), RMS post-fit residual = 4.204 (us) Fit Chisq = 328 Chisqr/nfree = 328.02/80 = 4.10028 pre/post = 1.32036 Number of points in fit = 90 PARAMETER Pre-fit Post-fit Uncertainty Difference Fit --------------------------------------------------------------------------------------------------- RAJ (rad) 2.71821351132165 2.71821366970554 4.5793e-07 1.5838e-07 Y RAJ (hms) 10:22:58.1188834 10:22:58.1210613 0.006297 0.0021779 DECJ (rad) 0.175100786106638 0.175101202092881 1.1575e-06 4.1599e-07 Y DECJ (dms) +10:01:57.12972 +10:01:57.21552 0.23875 0.085803 F0 (Hz) 60.7794489670958 60.7794489674466 1.2099e-10 3.5076e-10 Y F1 (s^-2) -1.69337759279488e-16 -1.70739820420136e-16 4.6312e-19 -1.4021e-18 Y PEPOCH (MJD) 50250 50250 0 0 N POSEPOCH (MJD) 50250 50250 0 0 N DM (cm^-3 pc) 10.1340857485791 10.1323540071461 0.00032389 -0.0017317 Y T0 50246.7162463696 50246.7162473185 8.2856e-07 9.4889e-07 Y PB 7.80513016588816 7.80513016328438 2.1745e-09 -2.6038e-09 Y A1 16.7654150843515 16.7654147901821 3.3958e-07 -2.9417e-07 Y OM 97.67 97.67 0 0 N ECC 9.73177041814313e-05 9.73614863096607e-05 4.0439e-08 4.3782e-08 Y TRACK (MJD) 0 0 0 0 N --------------------------------------------------------------------------------------------------- The user can use various "output format"-plugins to modify this style of output. The most general output-formats are called "general" and "general2". The "general" output format provides tools to output the fitted parameters: tempo2 -output general -s "{ERRMULT 2}{ALL_l} & {ALL_p} \\ \n" -f 1022.par 1022.tim -tempo1
gives an output such as RAJ & 10:22:58.121(13) \\ DECJ & +10:01:57.21552(1) \\ F0 & 60.7794489674(3) \\ F1 & -1.707E-16(10) \\ PEPOCH & 50250 \\ POSEPOCH & 50250 \\ DM & 10.1324(7) \\ T0 & 50246.7162473(17) \\ PB & 7.805130163(5) \\ A1 & 16.7654148(7) \\ OM & 97.67 \\ ECC & 9.736E-5(9) \\ where all the fitted uncertainties have been multipled by 2 (using ERRMULT 2). Other options are available such as printing positions in radians. The "general2" output format allows the user to obtain the residuals and arrival times in a generalised format. For instance, tempo2 -output general2 -s "bat = {bat} {TAB 30} postfit = {post} \n" -f 1022.par 1022.tim -tempo1
gives bat = 53316.913988559192532 postfit = -1.4013812949966899558e-06 bat = 53316.942347778044155 postfit = -8.9140037306238170828e-06 bat = 53339.763827992275925 postfit = -2.7661638801441797966e-06 bat = 53340.766243082893851 postfit = -3.9590484330153836507e-06 bat = 53341.767153434344575 postfit = -1.5820342343674639199e-05 bat = 53343.759018545078565 postfit = -3.0553744448713572345e-07 bat = 53344.769882986722987 postfit = -2.7194151293737169194e-06 bat = 53358.794030341607957 postfit = -1.0635224082231780844e-06 bat = 53359.788797078278918 postfit = -7.9941970336682482912e-06 bat = 53359.839033035550145 postfit = -6.2294153515564813482e-06 bat = 53374.722118052548574 postfit = 1.1433216401677192635e-06 bat = 53375.672422357200364 postfit = -9.4484079101972596806e-06 bat = 53376.709653164930661 postfit = -1.0458710000774904536e-05 bat = 53467.530353743119566 postfit = 5.1600086777362405918e-06 bat = 53468.496491265916422 postfit = -1.8190372589200010294e-06 bat = 53481.467843974453498 postfit = -1.2223221375857372388e-05 bat = 53483.3386372527915 postfit = 6.0164368757893214802e-06 bat = 53485.340318635574775 postfit = 1.3821827921105905752e-06 bat = 53500.446699057582236 postfit = -7.5602620743125784161e-06 Options include {BAT} to display barycentric arrival times, {SAT} for site-arrival times, {FREQ} for observing frequencies,{PRE} for pre-fit residauls,{POST} for post-fit residuals,{ERR} for TOA error and {BINPHASE} for binary phase. The covariance matrix for the fitted parameters can be obtained using the "matrix" output format: tempo2 -output matrix -f 1022.par 1022.tim gives Correlation matrix ...
F0 DM T0 PB A1 ECC
F0 +1.00000000
DM +0.04857778 +1.00000000
T0 -0.46829467 -0.13609983 +1.00000000
PB +0.47274520 +0.13568604 -0.99939906 +1.00000000
A1 -0.14504343 -0.08942360 +0.01717271 -0.01343955 +1.00000000
ECC -0.01786535 -0.08594389 +0.09468669 -0.09677360 -0.02684250 +1.00000000
gcor +0.51268893 +0.18087855 +0.99942275 +0.99942647 +0.22477523 +0.14251438
dp +0.3 +0.1 +3.2 +3.2 +0.1 +0.1
where gcor is a measure for the strongest correlation between the fitted variable and a linear combination of all other variables. dp provides an estimate of the number of "insignificant" digits that should be quoted in the timing solution. |