Usage¶
Fit 1 GRB SED¶
Import pyGRBz package:
import os
from pyGRBz.pyGRBz import GRB_photoZ
Instantiate the class
photoz = GRB_photoZ(output_dir='/results/Tuto/SED/')
Load the SED of GRB050904 stored in data/sed/
>>> photoz.load_data(data_dir='/data/sed/',data_name=['GRB050904'])
Observations:
Name time_since_burst band mag mag_err zp phot_sys detection telescope
--------- ---------------- ---- ----- ------- --- -------- --------- ---------
GRB050904 1 Ks 20.0 0.07 - AB 1 isaac
GRB050904 1 H 20.37 0.07 - AB 1 isaac
GRB050904 1 J 20.7 0.06 - AB 1 isaac
GRB050904 1 z 21.8 0.2 - AB 1 fors2
GRB050904 1 I 24.45 0.2 - AB 1 fors2
GRB050904 1 R 23.9 0.05 - AB 0 cafos
GRB050904 1 V 24.6 0.05 - AB 0 laica
Info about data:
name type RA_J2000 DEC_J2000 ... beta_inf beta_X beta_X_sup beta_X_inf
--------- ---- ---------- ------------ ... -------- ------ ---------- ----------
GRB050904 sed 0h54m50.6s +14d05m04.5s ... 0.3 -99 -99 -99
Formatting the data: apply Galactice correction if needed and compute fluxes in Jansky
Now data need to be corrected for galactic extinction if needed and fluxes expressed in microJy.
>>> photoz.formatting()
SEDS formatted:
Name time_since_burst band mag ... ext_mag flux flux_err
... microJy microJy
--------- ---------------- ---- ----- ... ------- -------------- ---------------
GRB050904 1 V 24.6 ... 0.0 0.52480746025 0.0241682766933
GRB050904 1 R 23.9 ... 0.0 1.0 0.0460517018599
GRB050904 1 I 24.45 ... 0.0 0.602559586074 0.110995577643
GRB050904 1 z 21.8 ... 0.0 6.91830970919 1.27439974441
GRB050904 1 J 20.7 ... 0.0 19.0546071796 1.05299650667
GRB050904 1 H 20.37 ... 0.0 25.8226019063 1.66484466993
GRB050904 1 Ks 20.0 ... 0.0 36.307805477 2.34085072622
The next Extract the SED at a given time.
In case the input data is already a SED. This function has to be run in order to have the right formatting for the follwing computations
photoz.extract_sed(model='SPL',method='ReddestBand')
Create flat priors
priors=dict(z=[0,11],Av=[0,2],beta=[0,2],norm=[0,10])
# Run the MCMC algorithm.
# Select the extinction law to used: 'smc', 'lmc', 'mw', 'nodust'
# Nthreads: number of threads to use in case of parallelisation
# nwalkers: number of walkers
# Nsteps1: number of steps for the first burn-in phase
# Nsteps2: number of steps for the second burn-in phase
# Nsteps3: number of steps for the production run
# Select to add dust, gas in host and our galaxy
# Select IGM transmission method: 'Madau' or 'Meiksin'
photoz.fit(ext_law='smc',Nthreads=4,sampler_type='ensemble',nwalkers=30,Nsteps1=300,Nsteps2=1000,nburn=300,Host_dust=True,Host_gas=False,MW_dust=False,MW_gas=False,DLA=False,igm_att='Meiksin',clean_data=False,plot_all=False,plot_deleted=False,priors=priors)