Observation#
- class gammapy.data.Observation(obs_id=None, meta=None, gti=None, aeff=None, edisp=None, psf=None, bkg=None, rad_max=None, events=None, obs_filter=None, pointing=None, location=None)[source]#
Bases:
object
In-memory observation.
- Parameters:
- obs_idint, optional
Observation id. Default is None
- aeff
EffectiveAreaTable2D
, optional Effective area. Default is None.
- edisp
EnergyDispersion2D
, optional Energy dispersion. Default is None.
- psf
PSF3D
, optional Point spread function. Default is None.
- bkg
Background3D
, optional Background rate model. Default is None.
- rad_max
RadMax2D
, optional Only for point-like IRFs: RAD_MAX table (energy dependent RAD_MAX) For a fixed RAD_MAX, create a RadMax2D with a single bin. Default is None.
- gti
GTI
, optional Table with GTI start and stop time. Default is None.
- events
EventList
, optional Event list. Default is None.
- obs_filter
ObservationFilter
, optional Observation filter. Default is None.
- pointing
FixedPointingInfo
, optional Pointing information. Default is None.
- location
EarthLocation
, optional Earth location of the observatory. Default is None.
Attributes Summary
A lazy FITS data descriptor.
Which HDUs are available.
Which IRFs are available.
A lazy FITS data descriptor.
A lazy FITS data descriptor.
Event list of the observation as an
EventList
.GTI of the observation as a
GTI
.Return metadata container.
Dead-time fraction (float).
Live-time duration in seconds as a
Quantity
.Observation time duration in seconds as a
Quantity
.Observatory location as an
EarthLocation
object.Get the pointing for the observation as a
FixedPointingInfo
object.A lazy FITS data descriptor.
Rad max IRF.
Target RA / DEC sky coordinates as a
SkyCoord
object.Midpoint between start and stop time as a
Time
object.Observation start time as a
Time
object.Observation stop time as a
Time
object.Methods Summary
check
([checks])Run checks.
copy
([in_memory])Copy observation.
create
(pointing[, location, obs_id, ...])Create an observation.
get_pointing_altaz
(time)Get the pointing in alt-az for given time.
get_pointing_icrs
(time)Get the pointing in ICRS for given time.
peek
([figsize])Quick-look plots in a few panels.
read
(event_file[, irf_file, checksum])Create an Observation from a Event List and an (optional) IRF file.
select_time
(time_interval)Select a time interval of the observation.
write
(path[, overwrite, format, ...])Write this observation into
Path
using the specified format.Attributes Documentation
- aeff#
A lazy FITS data descriptor.
- Parameters:
- cachebool
Whether to cache the data.
- available_hdus#
Which HDUs are available.
- available_irfs#
Which IRFs are available.
- bkg#
A lazy FITS data descriptor.
- Parameters:
- cachebool
Whether to cache the data.
- edisp#
A lazy FITS data descriptor.
- Parameters:
- cachebool
Whether to cache the data.
- meta#
Return metadata container.
- observation_dead_time_fraction#
Dead-time fraction (float).
Defined as dead-time over observation time.
Dead-time is defined as the time during the observation where the detector didn’t record events: https://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 as a
Quantity
.The dead-time-corrected observation time.
Computed as
t_live = t_observation * (1 - f_dead)
wheref_dead
is the dead-time fraction.
- observation_time_duration#
Observation time duration in seconds as a
Quantity
.The wall time, including dead-time.
- observatory_earth_location#
Observatory location as an
EarthLocation
object.
- pointing#
Get the pointing for the observation as a
FixedPointingInfo
object.
- psf#
A lazy FITS data descriptor.
- Parameters:
- cachebool
Whether to cache the data.
- rad_max#
Rad max IRF. None if not available.
Methods Documentation
- copy(in_memory=False, **kwargs)[source]#
Copy observation.
Overwriting
Observation
arguments requires thein_memory
argument to be true.- Parameters:
- in_memorybool, optional
Copy observation in memory. Default is False.
- **kwargsdict, optional
Keyword arguments passed to
Observation
.
- Returns:
- obs
Observation
Copied observation.
- obs
Examples
>>> from gammapy.data import Observation >>> obs = Observation.read("$GAMMAPY_DATA/hess-dl3-dr1/data/hess_dl3_dr1_obs_id_020136.fits.gz") >>> obs_copy = obs.copy(in_memory=True, obs_id=1234) >>> print(obs_copy)
- classmethod create(pointing, location=None, obs_id=0, livetime=None, tstart=None, tstop=None, irfs=None, deadtime_fraction=0.0, reference_time=<Time object: scale='utc' format='iso' value=2000-01-01 00:00:00.000>)[source]#
Create an observation.
User must either provide the livetime, or the start and stop times.
- Parameters:
- pointing
FixedPointingInfo
orSkyCoord
Pointing information.
- location
EarthLocation
, optional Earth location of the observatory. Default is None.
- obs_idint, optional
Observation ID as identifier. Default is 0.
- livetime~astropy.units.Quantity`, optional
Livetime exposure of the simulated observation. Default is None.
- tstart
Time
orQuantity
, optional Start time of observation as
Time
or duration relative toreference_time
. Default is None.- tstop
astropy.time.Time
orQuantity
, optional Stop time of observation as
Time
or duration relative toreference_time
. Default is None.- irfsdict, optional
IRFs used for simulating the observation:
bkg
,aeff
,psf
,edisp
,rad_max
. Default is None.- deadtime_fractionfloat, optional
Deadtime fraction. Default is 0.
- reference_time
Time
, optional the reference time to use in GTI definition. Default is
Time("2000-01-01 00:00:00")
.
- pointing
- Returns:
- obs
gammapy.data.MemoryObservation
Observation.
- obs
- peek(figsize=(15, 10))[source]#
Quick-look plots in a few panels.
- Parameters:
- figsizetuple, optional
Figure size. Default is (15, 10).
- classmethod read(event_file, irf_file=None, checksum=False)[source]#
Create an Observation from a Event List and an (optional) IRF file.
- Parameters:
- event_filestr or
Path
Path to the FITS file containing the event list and the GTI.
- irf_filestr or
Path
, optional Path to the FITS file containing the IRF components. Default is None. If None, the IRFs will be read from the event file.
- checksumbool
If True checks both DATASUM and CHECKSUM cards in the file headers. Default is False.
- event_filestr or
- Returns:
- observation
Observation
Observation with the events and the IRF read from the file.
- observation
- select_time(time_interval)[source]#
Select a time interval of the observation.
- Parameters:
- time_interval
astropy.time.Time
Start and stop time of the selected time interval. For now, we only support a single time interval.
- time_interval
- Returns:
- new_obs
Observation
A new observation instance of the specified time interval.
- new_obs
- write(path, overwrite=False, format='gadf', include_irfs=True, checksum=False)[source]#
Write this observation into
Path
using the specified format.- Parameters:
- pathstr or
Path
Path for the output file.
- overwritebool, optional
Overwrite existing file. Default is False.
- format{“gadf”}
Output format, currently only “gadf” is supported. Default is “gadf”.
- include_irfsbool, optional
Whether to include irf components in the output file. Default is True.
- checksumbool, optional
When True adds both DATASUM and CHECKSUM cards to the headers written to the file. Default is False.
- pathstr or