Syntax:
-BLS < "r" rmin rmax | "q" qmin qmax > minper maxper nfreq nbins timezone Npeak outperiodogram [outdir] omodel [model_outdir] correctlc ["fittrap"] ["nobinnedrms"] ["ophcurve" outdir phmin phmax phstep] ["ojdcurve" outdir jdstep] Example 1.$ ./vartools -i EXAMPLES/3.transit -ascii -oneline \ -BLS q 0.01 0.1 0.1 20.0 100000 200 0 1 \ 1 EXAMPLES/OUTDIR1/ 1 EXAMPLES/OUTDIR1/ 0 fittrap \ nobinnedrms ophcurve EXAMPLES/OUTDIR1/ -0.1 1.1 0.001 Name = EXAMPLES/3.transit BLS_Period_1_0 = 2.12334706 BLS_Tc_1_0 = 53727.297293937358 BLS_SN_1_0 = 7.26127 BLS_SR_1_0 = 0.00238 BLS_SDE_1_0 = 6.34195 BLS_Depth_1_0 = 0.01220 BLS_Qtran_1_0 = 0.03576 BLS_Qingress_1_0 = 0.19618 BLS_OOTmag_1_0 = 10.16686 BLS_i1_1_0 = 0.98213 BLS_i2_1_0 = 1.01790 BLS_deltaChi2_1_0 = -24217.21939 BLS_fraconenight_1_0 = 0.43155 BLS_Npointsintransit_1_0 = 165 BLS_Ntransits_1_0 = 4 BLS_Npointsbeforetransit_1_0 = 127 BLS_Npointsaftertransit_1_0 = 143 BLS_Rednoise_1_0 = 0.00151 BLS_Whitenoise_1_0 = 0.00489 BLS_SignaltoPinknoise_1_0 = 14.38935 BLS_Period_invtransit_0 = 1.14594782 BLS_deltaChi2_invtransit_0 = -3301.69183 BLS_MeanMag_0 = 10.16740
Apply the Box-Least Squares (BLS) transit-search algorithm to the light curve EXAMPLES/3.transit (an LC with a transit injected). At each trial frequency we scan fractional transit durations between 0.01 and 0.1 (the option q fixes the range, if we had used r then the range of transit durations to search would depend on the trial frequency). Periods between 0.1 and 20.0 days are searched. A total of 100000 frequencies are searched, and at each frequency we use 200 phase-bins. The time-zone is set to 0 (this only affects how the BLS_fraconenight output statistic is calculated). We only search for one peak in the BLS spectrum. The BLS spectrum is output to the directory EXAMPLES/OUTDIR1 (the -ascii option causes this to be written as an ascii file rather than the default binary file format), with the filename 3.transit.bls. The best-fit box-transit model is written to the directory EXAMPLES/OUTDIR1 with the filename 3.transit.bls.model. We do not subtract the best-fit transit before passing to the next command (in this example there are no further commands). By specifying fittrap we have the routine fit a trapezoid-shaped transit model after finding the top peak in the BLS spectrum. By specifying nobinnedrms we speed up the routine compared to the default behavior. We output a model transit phase curve to EXAMPLES/OUTDIR1/ (it will have the filename 3.transit.bls.phcurve), this can be used for overplotting the model on the data in the file bls.model (which is only sampled at the observed phases). The phase curve will go from -0.1 to 1.1 with a step-size of 0.001 in phase. By giving the -oneline option before the -BLS command we have the statistics written with one line per statistic.
Fig 1. BLS spectrum computed in Example 1.
Fig 2. Phased transit light curve and BLS model from Example 1.