Simple Box-Wing Light Curves

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2025-01-14 17:45:02.864 LightCurveEngine-mac-arm[96129:92725153] +[IMKClient subclass]: chose IMKClient_Modern
2025-01-14 17:45:02.864 LightCurveEngine-mac-arm[96129:92725153] +[IMKInputSession subclass]: chose IMKInputSession_Modern

3.2589705210411477 28.970679292357577

import matplotlib.pyplot as plt
import numpy as np

import mirage as mr

station = mr.Station()
obj = mr.SpaceObject('matlib_goes17.obj', identifier='GOES 17')

a_pan = 3.0 * 1.27  # m^2
a_bus = 0.8 * 1.1  # m^2


d0 = mr.utc(2024, 10, 18)
dates, epsecs = mr.date_linspace(d0, d0 + mr.hours(14), 100, return_epsecs=True)

r_obj = obj.propagate(dates)
svi = mr.sun(dates) - r_obj  # from obj to sun
ovi = station.j2000_at_dates(dates) - r_obj  # from obj to obs

f = (
    mr.AstroConstants.sun_irradiance_vacuum
    / (mr.vecnorm(ovi) ** 2 * 1e6)
    / (mr.vecnorm(svi) / mr.AstroConstants.au_to_km) ** 2
)
f = f.flatten()

attitude = mr.AlignedAndConstrainedAttitude(
    mr.hat(r_obj), mr.hat(svi), dates, axis_order=(2, 0, 1)
)

q_of_t, w_of_t = attitude.propagate(epsecs)
d_of_t = mr.quat_to_dcm(q_of_t)  # inertial to body

svb = mr.stack_mat_mult_vec(d_of_t, svi)
ovb = mr.stack_mat_mult_vec(d_of_t, ovi)

s = mr.hat(svi)
o = mr.hat(ovi)
h = mr.hat(s + o)
n_bus = -mr.hat(r_obj)
brdf = mr.Brdf('cook-torrance', cd=0.5, cs=0.5, n=0.5)

fr_pan = brdf.eval_normalized_brightness(s, o, s)
fr_bus = brdf.eval_normalized_brightness(s, o, n_bus)
lc_simp = (a_bus * fr_bus + a_pan * fr_pan).flatten()

lc_fancy = mr.run_light_curve_engine(
    brdf,
    obj,
    mr.hat(svb),
    mr.hat(ovb),
    show_window=True,
    verbose=False,
    rotate_panels=True,
    frame_rate=100,
    instances=1,
)

percent_err_at_peak = np.abs(lc_simp.max() - lc_fancy.max()) / lc_fancy.max() * 100
median_err = np.mean(np.abs(lc_simp - lc_fancy) / lc_fancy) * 100
print(percent_err_at_peak, median_err)

plt.figure(figsize=(4, 4))
plt.plot(epsecs / 3600, lc_fancy * f * 1e12, 'k', linewidth=2.5, label='Full Rendered')
plt.plot(epsecs / 3600, lc_simp * f * 1e12, 'c--', linewidth=2, label='Simplified')
plt.grid()
plt.legend()
plt.title('Integrated Irradiance of GOES 17')
plt.xlabel('Hours after 00:00 Oct 18, 2024 UTC')
plt.ylabel('Light Curve $10^{-12}$ [W / $m^2$]')
plt.tight_layout()

plt.figure(figsize=(4, 4))
plt.plot(
    epsecs / 3600,
    mr.irradiance_to_apparent_magnitude(lc_fancy * f),
    'k',
    linewidth=2.5,
    label='Full Rendered',
)
plt.plot(
    epsecs / 3600,
    mr.irradiance_to_apparent_magnitude(lc_simp * f),
    'c--',
    linewidth=2,
    label='Simplified',
)
plt.grid()
plt.legend()
plt.title('Apparent Magnitude of GOES 17')
plt.xlabel('Hours after 00:00 Oct 18, 2024 UTC')
plt.ylabel('Light Curve [nondim]')
plt.tight_layout()

plt.show()