How to run binara

File structure

Light curve files

There are two folders:

• folded_lightcurves

  • The folder that stores the folded light curves before the mcmc runs on them. Once you have a light curve from the neural network, you find the period, fold it based on that period, and then save that information to a .txt file. The file will contain a header with the number of data points in the .txt file and the period of the light curve in days. Then, the file will have 3 columns that contain the phase-folded time, normalized flux, and flux error.

  • Saving the folded light curve:

    t, y, yerr, *_ = load_tic_data(TIC_ID = [tic_id], sector = [sector])
    
    period = [period]
    
    phase = (t % period) / period
    
    sorted_idx = np.argsort(phase)
    phase = phase[sorted_idx]
    y = y[sorted_idx]
    yerr = yerr[sorted_idx]
    
    out_file = "[tic_id]_sector_[sector].txt"
    np.savetxt(out_file, np.column_stack([phase, y, yerr]),
               fmt="%.6f\t%.6f\t%.6f")
    
    print(f"Saved folded LC to {out_file}")
    

• mcmc_lightcurves

  • Once we start fitting the parameters, the best fit light curve that the mcmc produces is written in this directory. In the template there are two types of files, one with and one without gmag. It is better to use the gmag files because the mcmc uses gmag as an additional constraint to get better estimates. The gmag tag means that the g magnitude was used in estimating the values, but it is just a single value from the magnitudes folder. There are four columns in these files: time in days, flux of original folded light curve, flux of mcmc light curve, and the error in flux of the original light curve.

magnitudes

Example of file:

1000.
10.1232	2.76557439849598
-0.439	1.1237103791937538
0.8318800000000002	0.8063815510019341
0.6298999999999993	0.6608454503128677

The bottom three rows represent colors, but they are not currently being used. We only use the top 2 rows. The first row is the distance to the star in parsec, which comes from the tic_id. The first number in the second row is the gmag, and the second number in the second row is the uncertainty. You can still run the binara code without providing a magnitude file. If you don’t provide one, the code will still run, but it runs with default values. So, for a more accurate fit, it is best to include a magnitude file as an input.

pars

This file contains the same information that is in the chains directory. The file in the chains directory contains 2 additional values in the beginning: the log likelihood and the iteration number. The file in the pars directory contains the parameter values output by the best fit found by the run. It goes into the file in the chains directory, find which line has the lowest log likelihood, and then it copies the parameters of that line into the pars file. If you are only using data from one sector, then there are 22 parameters. The 22 parameters written in the file are in this order: logM1 (mass of primary star 1), logM2 (mass of primary star 2), logP (period), e (eccentricity), inc (inclination in rad), omega0 (angle or periastron in rad), T0 (initial time), rr1 (radius scaling factor of primary star), rr2 (radius scaling factor of secondary star), mu_1, tau_1, mu_2, tau_2, alpha_ref_1, alpha_ref_2, extra_alpha_beam_1, extra_alpha_beam_2, alpha_T1, alpha_T2, blending, flux_tune, and noise_rescaling. However, if you are using multiple sectors, 7 additional parameters are added for each additional sector. In likelihood.c, in the Log_Likelihood function, the variable npars_unique defines the values that are unique to each sector, and util.c shows that npars_unique is a constant set to 7. These 7 parameters are e, i, omega, t0, blending, flux_tune, and noise_rescaling.

py_initialize

This is a combined file created by the write_mcmc_data function. The header is 6 values that are the number of iterations, the number of chains run in that iteration, number of parameters, number of sectors, NPAST which is the number of past samples to remember per chain so the code learns from where it has already been, and dTemp, which is the difference in temperature between the chains.