Transport of
Nançay radio pulsar ephemeredes
to
the GLAST LAT
data servers
David A. Smith & Denis Dumora, 15 June 2006
Introduction: This text describes a dictionary between Tempo names of ephemeredes parameters as provided by the Nançay radio telescope and the parameter names used by the LAT Science Tools. This dictionary is implemented by partempo2Glastpdb.c written by Denis, available in partempo2Glastpdb.tar . We note that the Tempo files contain more information than the Science Tools provide for (e.g., uncertainties on the pulsar coordinates and rotation frequency), thus we recommend that the original files provided by the radio astronomers be archived.
The GSSC data servers provide pulsar timing ephemeredes in a data format compatible with the Science Tools. The ephemeredes database is a FITS file generically called “D4”, that can be created and updated by gtpulsardb. It is read by, for example, gtbary, gtpsearch, and gtpphase. Documentation can be found at
http://glast.gsfc.nasa.gov/ssc/dev/psr_tools/definitionD4.html
http://glast.gsfc.nasa.gov/ssc/dev/psr_tools/fakedata.html#dataset003
The tutorial provides input examples, of
which my_pulsardb_spin.txt (for the spin parameters) and
my_pulsardb_bin.txt for the binary
orbital elements are partially reproduced here:
SPIN_PARAMETERSPSRNAME RA DEC EPOCH_INT EPOCH_FRAC TOAGEO_INT TOAGEO_FRAC TOABARY_INT TOABARY_FRAC F0 F1 F2 RMS VALID_SINCE VALID_UNTIL BINARY_FLAG SOLAR_SYSTEM_EPHEMERIS OBSERVER_CODE# Data entries follow. Note that "" required for a value containing a white space."PSR J0014+4746" 3.572042 47.775997 54100 0.0 54100 .999997402 54100 .999997402 0.8059972761250 -3.63794E-16 3.28E-31 8.7 53929 54201 F "JPL DE200" J
ORBITAL_PARAMETERSPSRNAME PB PBDOT A1 ECC OM T0 GAMMA OBSERVER_CODE SOLAR_SYSTEM_EPHEMERIS ECCDOT XDOT OMDOT SHAPIRO_R SHAPIRO_S
The goal of the code is to fill in the values for the list of LAT parameter names.
Dictionary: Many but not all of the parameters are the same. The purpose of the following table is to highlight the principal differences.
For details refer to Denis’code and to the LAT and Tempo documentation (links above).
|
LAT D4 name (units) |
Tempo name (units) |
Tempo Example |
Tempo to LAT Conversion, and notes. |
|
PSRNAME |
PSR |
J1946+2611 |
(a) |
|
RA (decimal degree) |
RAJ (optional h:m:s) |
19:46:45.81000002 |
h:m:s => degrees |
|
DEC (decimal degree) |
DECJ (optional d:m:s) |
26:11:49.2000000 |
h:m:s => degrees |
|
No equivalent |
POSEPOCH (mjd) |
49079.5000 |
|
|
F0 |
F0 (Hz) (frequency flag error) |
2.2985609872240267 1 0.0000000000783993 |
(b) |
|
F1 |
F1
|
-1.163600000000E-13 |
|
|
F2 |
F2 |
|
(c) |
|
EPOCH_INT EPOCH_FRAC |
PEPOCH
(mjd) |
49079.500000 |
Break into integer and fractional parts |
|
VALID_SINCE |
START (mjd) |
53812.311 |
|
|
VALID_UNTIL |
FINISH (mjd) |
53862.214 |
|
|
|
DM
|
165.000000 |
|
|
SOLAR_SYSTEM_EPHEMERIS |
EPHEM |
DE200 |
|
|
No equivalent |
CLK |
UNCORR |
|
|
No equivalent |
NTOA |
99 |
|
|
RMS (pulsar milliperiods) |
TRES (microseconds)
|
590.27 |
rms=tres*f0/1000 |
TOAGEO_INT , TOAGEO_FRAC TOABARY_INT, TOABARY_FRAC |
TZRMJD (mjd) |
53812.31161112975441 |
(d) Break into integer and fractional parts |
|
No equivalent |
TZRFRQ
(MHz) |
1368.000 |
|
|
OBSERVER_CODE |
TZRSITE |
f |
|
|
No equivalent |
NITS |
1 |
|
|
No equivalent |
NPRNT |
2 |
|
|
BINARY_FLAG |
BINARY |
BT |
|
|
A1 (light seconds) |
A1 |
3.366685276 1 0.000000020 |
|
|
ECC |
E |
0.0000191681 1 0.0000000126 |
|
|
T0 |
T0 |
5000.493852084 1 0.000596096 |
|
|
PB |
PB |
5.741118855016 1 0.000013137617 |
|
|
PBDOT |
PBDOT |
7.568933
1 1.0899134 |
|
|
OM |
OM |
1.622808114146 1 0.037377875724 |
|
|
OMDOT |
OMDOT |
0.3051824 1
0.0524102 |
|
|
XDOT |
XDOT |
0.071290
1 0.000793 |
|
|
ECCDOT |
EDOT |
0.001893
1 0.000433 |
|
|
GAMMA |
|
|
|
|
SHAPIRO_R, SHAPIRO_S |
|
|
|
|
|
|
|
|
Notes:
(a)
The spin
parameters in this example were provided by Ismael Cognard (LPCE-CNRS and
Nançay Radio Observatory) while the binary parameters were taken from the Tempo
test file for 0437-4715.
(b)
The Tempo
flag “1” specifies the data format, e.g.
h:m:s vs decimal degrees and is an option for several of the Tempo
parameters.
(c)
If F2 is not
present in the input data then it is written out as F1²/2/F0.
(d)
The code presently writes the same values to
the TOAGEO and TOABARY, calculated as
TOA = TZRMJD –
DM/2.41E-4/TZRFRQ²