# The ON region center is defined in the icrs frame. The angle is defined w.r.t. to its axis.
on_region = RectangleSkyRegion(center=crab_position,
width=0.5 * u.deg,
height=0.4 * u.deg,
angle=0 * u.deg)
background_estimator = ReflectedRegionsBackgroundEstimator(
observations=observations, on_region=on_region, min_distance=0.1 * u.rad)
background_estimator.run()
# Let's inspect the data extracted in the first observation
print(background_estimator.result[0])
background_estimator.plot()
# Now we change the ON region, and use a center defined in the galactic frame
on_region_galactic = RectangleSkyRegion(
center=crab_position.galactic,
width=0.5 * u.deg,
height=0.4 * u.deg,
angle=0 * u.deg,
)
background_estimator = ReflectedRegionsBackgroundEstimator(
observations=observations,
on_region=on_region_galactic,
min_distance=0.1 * u.rad)
background_estimator.run()
# Next we will manually perform a background estimate by placing [reflected regions](https://docs.gammapy.org/dev/background/reflected.html) around the pointing position and looking at the source statistics. This will result in a [gammapy.background.BackgroundEstimate](https://docs.gammapy.org/dev/api/gammapy.background.BackgroundEstimate.html) that serves as input for other classes in gammapy.
# In[ ]:
background_estimator = ReflectedRegionsBackgroundEstimator(
observations=observations,
on_region=on_region,
exclusion_mask=exclusion_mask,
)
background_estimator.run()
# In[ ]:
plt.figure(figsize=(8, 8))
background_estimator.plot(add_legend=True)
# ## Source statistic
#
# Next we're going to look at the overall source statistics in our signal region. For more info about what debug plots you can create check out the [ObservationSummary](https://docs.gammapy.org/dev/api/gammapy.data.ObservationSummary.html#gammapy.data.ObservationSummary) class.
# In[ ]:
stats = []
for obs, bkg in zip(observations, background_estimator.result):
stats.append(ObservationStats.from_observation(obs, bkg))
print(stats[1])
obs_summary = ObservationSummary(stats)
fig = plt.figure(figsize=(10, 6))