Utilities

Several useful utilities used throughout various modules

Function tools

tatpulsar.utils.functions.cal_2dchisquare(data, f, F1, pepoch, nbins, F2=0, F3=0, F4=0)[source]

Calculate the chisquare distribution for 2-D frequency search on the pepoch time. For example, search in a two-dimensianal parameter space (\(M \times N\), as \(M\)-length frequency array, and \(N\)-length frequency derivative array).

\[\chi^2 = f_{0} \cdot (t-T_{\mathrm{ref}}) + \frac{1}{2} \cdot f_{1} \cdot (t-T_{\mathrm{ref}})^2 + \frac{1}{6} \cdot f_{2} \cdot (t-T_{\mathrm{ref}})^3 + \cdots,\]

where \(T_{\mathrm{ref}\) is the reference time, \(f_{0}\), \(f_{1}\), \(f_{2}\), …, are the parameters of pulsar.

Parameters

data : array-like

The time array of photons to calculate the chisquare

f : array-like

A set of frequencies to calculate the chisquare for event array

F1 : float, optional, default 0

The frequency derivative

pepoch : float

The reference time of pulsar timing parameters

nbins : int

The number of bins to fold profile

F2 : float, optional, default 0

The second frequency derivative

F3 : float, optional, default 0

The third frequency derivative

F4 : float, optional, default 0

The forth frequency derivative

Returns

chi_square : array-like

An \(M \times N\) array, as \(M\) is the length of frequency f, \(N\) is the length of frequency derivative F1

tatpulsar.utils.functions.cal_chisquare(data, f, pepoch, nbins, F1=0, F2=0, F3=0, F4=0, parallel=False)[source]

Calculate the Pearson-Chisquare value for given spinning parameters at given epoch time.

\[\chi^2 = f_{0} \cdot (t-T_{\mathrm{ref}}) + \frac{1}{2} \cdot f_{1} \cdot (t-T_{\mathrm{ref}})^2 + \frac{1}{6} \cdot f_{2} \cdot (t-T_{\mathrm{ref}})^3 + \cdots,\]

where \(T_{\mathrm{ref}\) is the reference time, \(f_{0}\), \(f_{1}\), \(f_{2}\), …, are the parameters of pulsar.

Parameters

data : array-like

The time array of photons to calculate the chisquare

f : array-like

A set of frequencies to calculate the chisquare for event array

pepoch : float

The reference time of pulsar timing parameters

nbins : int

The number of bins to fold profile

F1 : float, optional, default 0

The frequency derivative

F2 : float, optional, default 0

The second frequency derivative

F3 : float, optional, default 0

The third frequency derivative

F4 : float, optional, default 0

The forth frequency derivative

parallel : boolean, optional, default False

whether to use multi-core CPU to calculate the chisquare

Returns

chi_square : array-like

The calculated \(\chi^2\) array

tatpulsar.utils.functions.cal_event_gti(data, tgap=1)[source]

calculate the gti edges of given event data. if the time gap between two adjacent event is larger than tgap, it split the event into two intervals. Otherwise, we take the event as continous observation.

data: array-like: the event array
tgap: float: the critical time gap to split GTI

Returns: gtis: ndarray

the list of GTI array, example [[gti0_0, gti0_1], [gti1_0, gti1_1], …]

tatpulsar.utils.functions.ccf(f1, f2)[source]

Calculate the cross-correlation function for given data. f1 is the original signal f2 is probe signal(shift and test)

Returns

y : array-like

the ccf function distribution

delay : float

the index of the delay between the input data f2 and the f1

tatpulsar.utils.functions.gauss(x, a, x0, sigma)[source]: Gaussian function

tatpulsar.utils.functions.get_parameters(kwargs)[source]: get the parameters for searching The format of input could be a name of parfile, a dictionary, or standard python function arguments.

tatpulsar.utils.functions.lorentz(x, amp, cen, wid)[source]: Lorentz function

tatpulsar.utils.functions.met2mjd(data, telescope='fermi')[source]

Convert Mission Elapse Time (MET) to Modified Julian Date (MJD).

\[T_{\mathrm{MJD}} = T_{\mathrm{MET}}/86400 + \mathrm{MJDREF},\]

where MJDREF is the reference time for each mission.

Parameters

data : float

The MET time

telescope : str, default ‘fermi’

The name of the mission, support mission are {‘fermi’, ‘hxmt’, ‘nicer’, ‘gecam’, ‘nustar’, ‘ixpe’}

Returns

mjd : float

The MJD time

tatpulsar.utils.functions.mjd2met(data, telescope='fermi')[source]

Convert Modified Julian Date (MJD) to Mission Elapse Time (MET)

\[T_{\mathrm{MJD}} = T_{\mathrm{MET}}/86400 + \mathrm{MJDREF},\]

where MJDREF is the reference time for each mission.

Parameters

data : float

The MJD time

telescope : str, default ‘fermi’

The name of the mission, support mission are {‘fermi’, ‘hxmt’, ‘nicer’, ‘gecam’, ‘nustar’, ‘ixpe’}

Returns

met : float

The MET time

tatpulsar.utils.functions.print_loop_percentage(iterator_i, total, printstr='')[source]: print the percentage in a loop

tatpulsar.utils.functions.rms(x)[source]: root-mean-square function

Functions for GTI manipulation

tatpulsar.utils.gti.create_gti_fits(gti_template, outfile, tstart, tstop)[source]

write tstart and tstop array to a FITS file, based on the GTI FITS template

Parameters:

gti_templateFITS file
a GTI fits file as template

outfilefilename
the name of the output FITS file

tstartarray-like
array of GTIs start time

tstoparray-like
array of GTIs stop time

tatpulsar.utils.gti.create_gti_txt(outfile, tstart, tstop)[source]

create a text file storing the TSTART and TSTOP value, it’s normally used for hxmtscreen

Parameters

outfile : filename

the name of the output FITS file

tstartarray-like
array of GTIs start time

tstoparray-like
array of GTIs stop time

tatpulsar.utils.gti.gti_intersection(gti1, gti2)[source]

find the intersection for given gti1 and gti2.

Parameters

gti1: list

the list of input GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

gti2: list

the list of input GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

Returns

gti: list

the list of output GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

tatpulsar.utils.gti.gti_union(gti1, gti2)[source]

find the intersection for given gti1 and gti2.

Parameters

gti1: list

the list of input GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

gti2: list

the list of input GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

Returns

gti: list

the list of output GTI, the format of gti list is a 2D list: [[start, stop], [start, stop], … ,[start, stop]]

Class to read the TEMPO2 parameter file (.par)

class tatpulsar.utils.readpar.readpar(filepath)[source]

Class to parse the TEMPO2 parameter file (.par) The parameters in the ‘.par’ file might be capitalized but those parameters stored in this object are case INSENSITIVE (see examples below).

Examples

>>> eph = readpar('test.par')
>>> print("F0 = ", eph.F0.value, eph.f0.value)
>>> F0 =  29.636679699921209437
>>> print("F0 error = ", eph.F0.error)
>>> F0 error =  1.7247236495e-09
>>> print("PEPOCH = ", eph.PEPOCH.value)
>>> PEPOCH =  58066.18087539147382
>>> print("PEPOCH error = ", eph.PEPOCH.error)
>>> PEPOCH error =  None