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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Rømer and Light Travel Time Effects (ltte)
Setup
Let's first make sure we have the latest version of PHOEBE 2.2 installed. (You can comment out this line if you don't use pip for your installation or don't want to update to the latest release).
Step1:  As always, let's do imports and initialize a logger and a new Bundle.  See Building a System for more details.
Step2:  Now let's add a light curve dataset to see how ltte affects the timings of eclipses.
Step3:  Relevant Parameters
The 'ltte' parameter in context='compute' defines whether light travel time effects are taken into account or not.
Step4:  Comparing with and without ltte
In order to have a binary system with any noticeable ltte effects, we'll set a somewhat extreme mass-ratio and semi-major axis.
Step5:  We'll just ignore the fact that this will be a completely unphysical system since we'll leave the radii and temperatures alone despite somewhat ridiculous masses - but since the masses and radii disagree so much, we'll have to abandon atmospheres and use blackbody.
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Python Code:
!pip install -I "phoebe>=2.2,<2.3"
Explanation: Rømer and Light Travel Time Effects (ltte)
Setup
Let's first make sure we have the latest version of PHOEBE 2.2 installed. (You can comment out this line if you don't use pip for your installation or don't want to update to the latest release).
End of explanation
%matplotlib inline
import phoebe
from phoebe import u # units
import numpy as np
import matplotlib.pyplot as plt
logger = phoebe.logger('error')
b = phoebe.default_binary()
Explanation: As always, let's do imports and initialize a logger and a new Bundle.  See Building a System for more details.
End of explanation
b.add_dataset('lc', times=phoebe.linspace(-0.05, 0.05, 51), dataset='lc01')
Explanation: Now let's add a light curve dataset to see how ltte affects the timings of eclipses.
End of explanation
print(b['ltte@compute'])
Explanation: Relevant Parameters
The 'ltte' parameter in context='compute' defines whether light travel time effects are taken into account or not.
End of explanation
b['sma@binary'] = 100
b['q'] = 0.1
Explanation: Comparing with and without ltte
In order to have a binary system with any noticeable ltte effects, we'll set a somewhat extreme mass-ratio and semi-major axis.
End of explanation
b.set_value_all('atm', 'blackbody')
b.set_value_all('ld_mode', 'manual')
b.set_value_all('ld_func', 'logarithmic')
b.run_compute(irrad_method='none', ltte=False, model='ltte_off')
b.run_compute(irrad_method='none', ltte=True, model='ltte_on')
afig, mplfig = b.plot(show=True)
Explanation: We'll just ignore the fact that this will be a completely unphysical system since we'll leave the radii and temperatures alone despite somewhat ridiculous masses - but since the masses and radii disagree so much, we'll have to abandon atmospheres and use blackbody.
End of explanation
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