PhotoManip

PhotoManip is a package to manipulate, convert and model SNe Photometry.

Credit

If you use PhotoManip, please cite Soumagnac et al. 2019 (in preparation)

How to install PhotoManip?

pip

pip install PhotoManip

Python version

• python 3

Required python packages

• math
• numpy
• scipy
• pylab
• emcee
• pylab
• pandas
• csv

How to run PhotoManip?

Before running anything, you first need to define the path of a directory where all your transmission curves are stored. We provide such a directory together with the package!.

(All the examples below are ran from within the test directory).

>>> import PhotoManip
>>> from PhotoManip import PhotoManip_fun
>>> filters_directory='../../Filters' 

Convert a mag (AB) value in a given band into a flux value.

PhotoManip does that using synthetic photometry, in a way similar to the (great) Pyphot package by Morgan Fouesneau.

>>> mag_value=20.55 #this is the magAB  value to convert
>>> flux=PhotoManip_fun.magAB_in_filter_to_flux_in_filter(mag_value,Filter_vector=np.array([['swift','UVW2']]),filters_directory=filters_directory,verbose=False)
>>> print('the flux is',flux)
flux is 1.55285808219e-16

Convert data downloaded from the Marshall into the format 'jd','mag','magerr','flux','fluxerr','absmag','absmagerr','filter','instr'.

First define the path of the photometry file downloaded from the Marshall

data_path='./data_Marshall_test.txt'# a file downloaded from the Marshall

Then define the path of the output file

output_path='./data_formatted_test.txt' #path to the file with the right format

Then run

PhotoManip_fun.read_data_Marshall_simple(data_path,no99=True,filters_directory=filters_directory,output_path=output_path)

Calculate the time "tref" at which the flux in a given band crosses zero

The explosion date is often approximated by the extrapolated time at which the flux (e.g. in the r-band) crosses zero. PhotoManip allows you to calculate this time by modeling the light curve with

1. a concave exponent
2. a power law

and then chosing the best model.

First, specify the band you would like to use (r or g), the path to the data (the data should be in the format 'jd','mag','magerr','flux','fluxerr','absmag','absmagerr','filter','instr'; see in the previous section how to produce such format from Marshall-downloaded data) and the number of points you would like to include in the fit:

data='./data_formatted_test.txt'
band='r'
days_rising=10

Then run

tref=PhotoManip_fun.tref_from_P48('./data_formated_aatqzim.txt',band=band,days_rising=days_rising)[0]

The code will first show you the light curve and number of points to include in the fit, and warn you to adjust the days_rising parameter.

***************************************************
******* IMPORTANT CHECK BEFORE YOU PROCEED ********
The red points shwon on the plot are the points which will be used for the fit.Adjust the "days_rising" parameter of Photomanip_fun.tref_from_P48, untill the red points cover all (and do not go beyond) the rising part of the light curve!
***************************************************

It will then run mcmc (using the emcee package) to model the rising chunk with both a concave exponent and a power law, output plots and summarize the results for you:

**********************************************************
****** SUMMARY OF tref CALCULATION WITH BOTH MODELS ******
**********************************************************
exponential:
t_ref=2458350.876016173, chi2_reduced=0.5049569769848575
power law:
t_ref=2458351.707039889, chi2_reduced=0.6557059506043315
the best fit is obtained with the exponential, i.e. tref=2458350.876016173

All plots can be found in the results_tref_calculator_from_P48R directory (or results_tref_calculator_from_P48G depending on the band you chose).

Give it a try with the test data!

All the figures above were obtained by running PhotoManip on the multiple-bands light curve of the Supernova 2018fif (Soumagnac et al 2019). The data is available in the test directory (including the output of the time-consuming interpolation step). You can reproduce all these results and figures by running PhotoManip the above examples in the test directory.