Observation

class gammapy.data.Observation(obs_id=None, obs_info=None, gti=None, aeff=None, edisp=None, psf=None, bkg=None, events=None, obs_filter=None)[source]

Bases: object

In-memory observation.

Parameters
obs_idint

Observation id

obs_infodict

Observation info dict

aeffEffectiveAreaTable2D

Effective area

edispEnergyDispersion2D

Energy dispersion

psfPSF3D

Point spread function

bkgBackground3D

Background rate model

gtiGTI

Table with GTI start and stop time

eventsEventList

Event list

obs_filterObservationFilter

Observation filter.

Attributes Summary

aeff

A lazy FITS data descriptor.

bkg

A lazy FITS data descriptor.

edisp

A lazy FITS data descriptor.

events

fixed_pointing_info

Fixed pointing info for this observation (FixedPointingInfo).

gti

muoneff

Observation muon efficiency.

observation_dead_time_fraction

Dead-time fraction (float).

observation_live_time_duration

Live-time duration in seconds (Quantity).

observation_time_duration

Observation time duration in seconds (Quantity).

observatory_earth_location

Observatory location (EarthLocation).

pointing_altaz

Pointing ALT / AZ sky coordinates (SkyCoord).

pointing_radec

Pointing RA / DEC sky coordinates (SkyCoord).

pointing_zen

Pointing zenith angle sky (Quantity).

psf

A lazy FITS data descriptor.

target_radec

Target RA / DEC sky coordinates (SkyCoord).

tstart

Observation start time (Time).

tstop

Observation stop time (Time).

Methods Summary

check([checks])

Run checks.

create(pointing[, obs_id, livetime, tstart, …])

Create an observation.

peek([figsize])

Quick-look plots in a few panels.

select_time(time_interval)

Select a time interval of the observation.

Attributes Documentation

aeff

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

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
fixed_pointing_info

Fixed pointing info for this observation (FixedPointingInfo).

gti
muoneff

Observation muon efficiency.

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 (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 (Quantity).

The wall time, including dead-time.

observatory_earth_location

Observatory location (EarthLocation).

pointing_altaz

Pointing ALT / AZ sky coordinates (SkyCoord).

pointing_radec

Pointing RA / DEC sky coordinates (SkyCoord).

pointing_zen

Pointing zenith angle sky (Quantity).

psf

A lazy FITS data descriptor.

Parameters
cachebool

Whether to cache the data.

target_radec

Target RA / DEC sky coordinates (SkyCoord).

tstart

Observation start time (Time).

tstop

Observation stop time (Time).

Methods Documentation

check(checks='all')[source]

Run checks.

This is a generator that yields a list of dicts.

classmethod create(pointing, obs_id=0, livetime=None, tstart=None, tstop=None, irfs=None, deadtime_fraction=0.0, reference_time='2000-01-01')[source]

Create an observation.

User must either provide the livetime, or the start and stop times.

Parameters
pointingSkyCoord

Pointing position

obs_idint

Observation ID as identifier

livetime~astropy.units.Quantity`

Livetime exposure of the simulated observation

tstartQuantity

Start time of observation w.r.t reference_time

tstopQuantity w.r.t reference_time

Stop time of observation

irfsdict

IRFs used for simulating the observation: bkg, aeff, psf, edisp

deadtime_fractionfloat, optional

Deadtime fraction, defaults to 0

reference_timeTime

the reference time to use in GTI definition

Returns
obsgammapy.data.MemoryObservation
peek(figsize=(12, 10))[source]

Quick-look plots in a few panels.

Parameters
figszietuple

Figure size

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