EventList¶
-
class
gammapy.data.
EventList
(table)[source]¶ Bases:
gammapy.data.EventListBase
Event list for IACT dataset.
Data format specification: EVENTS
For further information, see the base class:
EventListBase
.- Parameters
- table
Table
Event list table
- table
Examples
To load an example H.E.S.S. event list:
>>> from gammapy.data import EventList >>> filename = '$GAMMAPY_DATA/hess-dl3-dr1/data/hess_dl3_dr1_obs_id_023523.fits.gz' >>> events = EventList.read(filename)
Attributes Summary
ALT / AZ position computed from RA / DEC (
SkyCoord
).ALT / AZ frame (
AltAz
).ALT / AZ position from table (
SkyCoord
).Event energies (
Quantity
).Event Galactic sky coordinates (
SkyCoord
).Dead-time fraction (float).
Live-time duration in seconds (
Quantity
).Observation time duration in seconds (
Quantity
).Observation stop time (
Time
).Observation start time (
Time
).Observatory location (
EarthLocation
).Event offset from the array pointing position (
Angle
).Pointing RA / DEC sky coordinates (
SkyCoord
).Event RA / DEC sky coordinates (
SkyCoord
).Event times (
Time
).Time reference (
Time
).Methods Summary
check
(self[, checks])Run checks.
map_coord
(self, geom)Event map coordinates for a given geometry.
peek
(self)Quick look plots.
plot_energy
(self[, ax, ebounds])Plot counts as a function of energy.
plot_energy_offset
(self[, ax])Plot counts histogram with energy and offset axes.
plot_image
(self)Quick look counts map sky plot.
plot_offset2_distribution
(self[, ax, center])Plot offset^2 distribution of the events.
plot_time
(self[, ax])Plots an event rate time curve.
read
(filename, \*\*kwargs)Read from FITS file.
select_energy
(self, energy_band)Select events in energy band.
select_map_mask
(self, mask)Select events inside a mask (
EventList
).select_offset
(self, offset_band)Select events in offset band.
select_parameter
(self, parameter, band)Select events with respect to a specified parameter.
select_region
(self, region[, wcs])Select events in given region.
select_row_subset
(self, row_specifier)Select table row subset.
select_time
(self, time_interval)Select events in time interval.
stack
(event_lists, \*\*kwargs)Stack (concatenate) list of event lists.
Attributes Documentation
-
observation_dead_time_fraction
¶ Dead-time fraction (float).
This is a keyword related to IACTs Defined as dead-time over observation time.
Dead-time is defined as the time during the observation where the detector didn’t record events: http://en.wikipedia.org/wiki/Dead_time https://ui.adsabs.harvard.edu/abs/2004APh….22..285F
The dead-time fraction is used in the live-time computation, which in turn is used in the exposure and flux computation.
-
observation_live_time_duration
¶ Live-time duration in seconds (
Quantity
).The dead-time-corrected observation time.
In Fermi-LAT it is automatically provided in the header of the event list.
In IACTs is computed as
t_live = t_observation * (1 - f_dead)
where
f_dead
is the dead-time fraction.
-
observation_time_duration
¶ Observation time duration in seconds (
Quantity
).This is a keyword related to IACTs The wall time, including dead-time.
-
observatory_earth_location
¶ Observatory location (
EarthLocation
).
-
time
¶ Event times (
Time
).Notes
Times are automatically converted to 64-bit floats. With 32-bit floats times will be incorrect by a few seconds when e.g. adding them to the reference time.
Methods Documentation
-
check
(self, checks='all')¶ Run checks.
This is a generator that yields a list of dicts.
-
map_coord
(self, geom)¶ Event map coordinates for a given geometry.
-
plot_energy
(self, ax=None, ebounds=None, **kwargs)¶ Plot counts as a function of energy.
-
plot_energy_offset
(self, ax=None)¶ Plot counts histogram with energy and offset axes.
-
plot_offset2_distribution
(self, ax=None, center=None, **kwargs)¶ Plot offset^2 distribution of the events.
The distribution shown in this plot is for this quantity:
offset = center.separation(events.radec).deg offset2 = offset ** 2
Note that this method is just for a quicklook plot.
If you want to do computations with the offset or offset^2 values, you can use the line above. As an example, here’s how to compute the 68% event containment radius using
numpy.percentile
:import numpy as np r68 = np.percentile(offset, q=68)
- Parameters
- ax
Axes
(optional) Axes
- center
astropy.coordinates.SkyCoord
Center position for the offset^2 distribution. Default is the observation pointing position.
- **kwargs :
Extra keyword arguments are passed to
matplotlib.pyplot.hist
.
- ax
- Returns
- ax
Axes
Axes
- ax
Examples
Load an example event list:
>>> from gammapy.data import EventList >>> events = EventList.read('$GAMMAPY_DATA/hess-dl3-dr1/data/hess_dl3_dr1_obs_id_023523.fits.gz')
Plot the offset^2 distribution wrt. the observation pointing position (this is a commonly used plot to check the background spatial distribution):
>>> events.plot_offset2_distribution()
Plot the offset^2 distribution wrt. the Crab pulsar position (this is commonly used to check both the gamma-ray signal and the background spatial distribution):
>>> import numpy as np >>> from astropy.coordinates import SkyCoord >>> center = SkyCoord(83.63307, 22.01449, unit='deg') >>> bins = np.linspace(start=0, stop=0.3 ** 2, num=30) >>> events.plot_offset2_distribution(center=center, bins=bins)
Note how we passed the
bins
option ofmatplotlib.pyplot.hist
to control the histogram binning, in this case 30 bins ranging from 0 to (0.3 deg)^2.
-
plot_time
(self, ax=None)¶ Plots an event rate time curve.
-
classmethod
read
(filename, **kwargs)¶ Read from FITS file.
Format specification: EVENTS
- Parameters
- filename
pathlib.Path
, str Filename
- filename
-
select_energy
(self, energy_band)¶ Select events in energy band.
- Parameters
- energy_band
Quantity
Energy band
[energy_min, energy_max)
- energy_band
- Returns
- event_list
EventList
Copy of event list with selection applied.
- event_list
Examples
>>> from astropy.units import Quantity >>> from gammapy.data import EventList >>> event_list = EventList.read('events.fits') >>> energy_band = Quantity([1, 20], 'TeV') >>> event_list = event_list.select_energy()
-
select_parameter
(self, parameter, band)¶ Select events with respect to a specified parameter.
- Parameters
- parameterstr
Parameter used for the selection. Must be present in
self.table
.- bandtuple or
astropy.units.Quantity
Min and max value for the parameter to be selected (min <= parameter < max). If parameter is not dimensionless you have to provide a Quantity.
- Returns
- event_list
EventList
Copy of event list with selection applied.
- event_list
Examples
>>> from gammapy.data import EventList >>> event_list = EventList.read('events.fits') >>> phase_region = (0.3, 0.5) >>> event_list = event_list.select_parameter(parameter='PHASE', band=phase_region)
-
select_region
(self, region, wcs=None)¶ Select events in given region.
-
select_row_subset
(self, row_specifier)¶ Select table row subset.
- Parameters
- row_specifierslice, int, or array of ints
Specification for rows to select, passed on to
self.table[row_specifier]
.
- Returns
- event_list
EventList
New event list with table row subset selected
- event_list
Examples
Use a boolean mask as
row_specifier
:mask = events.table[‘FOO’] > 42 events2 = events.select_row_subset(mask)
Use row index array as
row_specifier
:idx = np.where(events.table[‘FOO’] > 42)[0] events2 = events.select_row_subset(idx)
-
select_time
(self, time_interval)¶ Select events in time interval.
- Parameters
- time_interval
astropy.time.Time
Start time (inclusive) and stop time (exclusive) for the selection.
- time_interval
- Returns
- events
EventList
Copy of event list with selection applied.
- events