Observation#

class gammapy.data.Observation(obs_id=None, meta=None, obs_info=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
obs_infodict, optional: Observation info dict. Default is None.
aeffEffectiveAreaTable2D, optional: Effective area. Default is None.
edispEnergyDispersion2D, optional: Energy dispersion. Default is None.
psfPSF3D, optional: Point spread function. Default is None.
bkgBackground3D, optional: Background rate model. Default is None.
rad_maxRadMax2D, 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.
gtiGTI, optional: Table with GTI start and stop time. Default is None.
eventsEventList, optional: Event list. Default is None.
obs_filterObservationFilter, optional: Observation filter. Default is None.
pointingFixedPointingInfo, optional: Pointing information. Default is None.
locationEarthLocation, optional: Earth location of the observatory. Default is None.

Attributes Summary

`aeff`	A lazy FITS data descriptor.
`available_hdus`	Which HDUs are available.
`available_irfs`	Which IRFs are available.
`bkg`	A lazy FITS data descriptor.
`edisp`	A lazy FITS data descriptor.
`events`	Event list of the observation as an `EventList`.
`gti`	GTI of the observation as a `GTI`.
`meta`	Return metadata container.
`muoneff`	Deprecated since version v1.2.
`obs_info`	Observation information dictionary.
`observation_dead_time_fraction`	Dead-time fraction (float).
`observation_live_time_duration`	Live-time duration in seconds as a `Quantity`.
`observation_time_duration`	Observation time duration in seconds as a `Quantity`.
`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.
`rad_max`	Rad max IRF.
`target_radec`	Target RA / DEC sky coordinates as a `SkyCoord` object.
`tmid`	Midpoint between start and stop time as a `Time` object.
`tstart`	Observation start time as a `Time` object.
`tstop`	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.

events#: Event list of the observation as an EventList.

gti#: GTI of the observation as a GTI.

meta#: Return metadata container.

muoneff#: Deprecated since version v1.2: Access additional metadata directly in obs.meta.opt.

Observation muon efficiency.

obs_info#: Observation information dictionary.

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) where f_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.

target_radec#: Target RA / DEC sky coordinates as a SkyCoord object.

tmid#: Midpoint between start and stop time as a Time object.

tstart#: Observation start time as a Time object.

tstop#: Observation stop time as a Time object.

Methods Documentation

check(checks='all')[source]#

Run checks.

This is a generator that yields a list of dictionary.

copy(in_memory=False, **kwargs)[source]#

Copy observation.

Overwriting Observation arguments requires the in_memory argument to be true.

Parameters

in_memorybool, optional: Copy observation in memory. Default is False.
**kwargsdict, optional: Keyword arguments passed to Observation.

Returns

obsObservation: Copied observation.

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

pointingFixedPointingInfo or SkyCoord: Pointing information.
locationEarthLocation, 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.
tstartTime or Quantity, optional: Start time of observation as Time or duration relative to reference_time. Default is None.
tstopastropy.time.Time or Quantity, optional: Stop time of observation as Time or duration relative to reference_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_timeTime, optional: the reference time to use in GTI definition. Default is Time("2000-01-01 00:00:00").

Returns

obsgammapy.data.MemoryObservation: Observation.

get_pointing_altaz(time)[source]#: Get the pointing in alt-az for given time.

get_pointing_icrs(time)[source]#: Get the pointing in ICRS for given time.

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.

Returns

observationObservation: Observation with the events and the IRF read from the file.

select_time(time_interval)[source]#

Select a time interval of the observation.

Parameters

time_intervalastropy.time.Time: Start and stop time of the selected time interval. For now, we only support a single time interval.

Returns

new_obsObservation: A new observation instance of the specified time interval.

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.