Transit injection

Generate a Mandel-Agol transit model for a light curve with all parameters fixed. The model is written to OUTDIR1/3.mandelagoltransit.model; adding that signal to the original LC produces a realistic noisy transit LC suitable for recovery tests (see the transit search & fit example).

Command line

./vartools -i EXAMPLES/3 \
    -MandelAgolTransit 2.12345 53725.174 0.1 10.0 i 90.0 0. 0. 0 \
        quad 0.236 0.391 \
        0 0 0 0 0 0 0 0 0 0 0 1 EXAMPLES/OUTDIR1 \
    -header

gawk '{print $1, $2 + $3, $4}' \
    EXAMPLES/OUTDIR1/3.mandelagoltransit.model > EXAMPLES/3.transit

#Name MandelAgolTransit_Period_0 MandelAgolTransit_T0_0 MandelAgolTransit_r_0 \
MandelAgolTransit_a_0 MandelAgolTransit_bimpact_0 MandelAgolTransit_inc_0 \
MandelAgolTransit_e_0 MandelAgolTransit_omega_0 MandelAgolTransit_mconst_0 \
MandelAgolTransit_ldcoeff1_0 MandelAgolTransit_ldcoeff2_0 \
MandelAgolTransit_chi2_0
EXAMPLES/3  2.12345000 53725.17400000   0.10000  10.00000   0.00000  90.00000 \
  0.00000   0.00000   0.00000   0.23600   0.39100 129730808.07162

Python

import pyvartools as vt
from pyvartools import commands as cmd

lc = vt.LightCurve.from_file("EXAMPLES/3")

result = (vt.Pipeline()
        .MandelAgolTransit(
            P0=2.12345, T00=53725.174, r0=0.1, a0=10.0, inclination=90.0,
            e0=0.0, omega0=0.0, mconst0=0.0,
            ld_type="quad", ld_coeffs=[0.236, 0.391],
            fitephem=0, fitr=0, fita=0, fitinclterm=0, fite=0, fitomega=0,
            fitmconst=0, fitldcoeffs=[0, 0],
            correct_lc=False,
            save_model=True,
        )).run(lc)

print(result.vars)

Name                                          3
MandelAgolTransit_Period_0              2.12345
MandelAgolTransit_T0_0                53725.174
MandelAgolTransit_r_0                       0.1
MandelAgolTransit_a_0                      10.0
MandelAgolTransit_bimpact_0                 0.0
MandelAgolTransit_inc_0                    90.0
MandelAgolTransit_e_0                       0.0
MandelAgolTransit_omega_0                   0.0
MandelAgolTransit_mconst_0                  0.0
MandelAgolTransit_ldcoeff1_0              0.236
MandelAgolTransit_ldcoeff2_0              0.391
MandelAgolTransit_chi2_0        129730808.07162

Notes

Parameters passed to -MandelAgolTransit: period 2.12345 d, T0 = 53725.174, Rp/R = 0.1, a/R = 10.0, inclination 90 degrees (transit central), circular orbit, quadratic limb darkening with coefficients (0.236, 0.391). The long run of zeros are the fitephem fitr fita fitinclterm fite fitomega fitmconst fitldcoeff1 fitldcoeff2 fitRV correctlc flags; everything is held fixed and the LC is not corrected. The final 1 EXAMPLES/OUTDIR1 writes the model to disk.

The CLI pipeline writes only the model, so a second step (gawk in the original example, or -Injecttransit if you want a single-call run) is needed to add that model onto the observed LC and save the result to EXAMPLES/3.transit, which the next example uses as its input.

Variation: one-step injection with -Injecttransit

-Injecttransit creates a noisy transit LC in a single step without the external gawk call. It takes physical parameters (Rp, Mp, Mstar, Rstar) rather than a/R*, and it adds the model to the LC in-place:

./vartools -i EXAMPLES/3 \
    -Injecttransit fix 2.12345 Rpfix 0.1 Mpfix 0.001 phasefix 0.0 \
        sinifix 1.0 eomega efix 0 ofix 0 Mstarfix 1.0 Rstarfix 1.0 \
        quad 0.236 0.391 0 \
    -o EXAMPLES/3.transit \
    -header

The Python equivalent uses cmd.Injecttransit(...) followed by cmd.o(...).