GTI#

class gammapy.data.GTI(table)[source]#

Bases: object

Good time intervals (GTI) Table.

Data format specification: GTI

Note: at the moment dead-time and live-time is in the EVENTS header … the GTI header just deals with observation times.

Parameters
tableTable

GTI table

Examples

Load GTIs for a H.E.S.S. event list:

>>> from gammapy.data import GTI
>>> gti = GTI.read('$GAMMAPY_DATA/hess-dl3-dr1//data/hess_dl3_dr1_obs_id_023523.fits.gz')
>>> print(gti)
GTI info:
- Number of GTIs: 1
- Duration: 1687.0 s
- Start: 123890826.0 s MET
- Start: 2004-12-04T22:08:10.184 (time standard: TT)
- Stop: 123892513.0 s MET
- Stop: 2004-12-04T22:36:17.184 (time standard: TT)

Load GTIs for a Fermi-LAT event list:

>>> gti = GTI.read("$GAMMAPY_DATA/fermi-3fhl-gc/fermi-3fhl-gc-events.fits.gz")
>>> print(gti)
GTI info:
- Number of GTIs: 39042
- Duration: 183139597.9032163 s
- Start: 239557417.49417615 s MET
- Start: 2008-08-04T15:44:41.678 (time standard: TT)
- Stop: 460250000.0 s MET
- Stop: 2015-08-02T23:14:24.184 (time standard: TT)

Attributes Summary

time_delta

GTI durations in seconds (Quantity).

time_intervals

List of time intervals

time_ref

Time reference (Time).

time_start

GTI start times (Time).

time_stop

GTI end times (Time).

time_sum

Sum of GTIs in seconds (Quantity).

Methods Summary

copy()

create(start, stop[, reference_time])

Creates a GTI table from start and stop times.

from_stack(gtis, **kwargs)

Stack (concatenate) list of event lists.

from_time_intervals(time_intervals[, ...])

From list of time intervals

group_table(time_intervals[, atol])

Compute the table with the info on the group to which belong each time interval.

read(filename[, hdu])

Read from FITS file.

select_time(time_interval)

Select and crop GTIs in time interval.

stack(other)

Stack with another GTI in place.

to_table_hdu([format])

Convert this GTI instance to a astropy.io.fits.BinTableHDU.

union([overlap_ok, merge_equal])

Union of overlapping time intervals.

write(filename, **kwargs)

Write to file.

Attributes Documentation

time_delta#

GTI durations in seconds (Quantity).

time_intervals#

List of time intervals

time_ref#

Time reference (Time).

time_start#

GTI start times (Time).

time_stop#

GTI end times (Time).

time_sum#

Sum of GTIs in seconds (Quantity).

Methods Documentation

copy()[source]#
classmethod create(start, stop, reference_time='2000-01-01')[source]#

Creates a GTI table from start and stop times.

Parameters
startTime or Quantity

Start times, if a quantity then w.r.t. reference time

stopTime or Quantity

Stop times, if a quantity then w.r.t. reference time

reference_timeTime

the reference time to use in GTI definition

classmethod from_stack(gtis, **kwargs)[source]#

Stack (concatenate) list of event lists.

Calls vstack.

Parameters
gtislist of GTI

List of good time intervals to stack

**kwargsdict

Keywords passed on to vstack

Returns
gtiGTI

Stacked good time intervals.

classmethod from_time_intervals(time_intervals, reference_time='2000-01-01')[source]#

From list of time intervals

Parameters
time_intervalslist of Time objects

Time intervals

reference_timeTime

Reference time to use in GTI definition

Returns
gtiGTI

GTI table.

group_table(time_intervals, atol='1e-6 s')[source]#

Compute the table with the info on the group to which belong each time interval.

The t_start and t_stop are stored in MJD from a scale in “utc”.

Parameters
time_intervalslist of astropy.time.Time

Start and stop time for each interval to compute the LC

atolQuantity

Tolerance value for time comparison with different scale. Default 1e-6 sec.

Returns
group_tableTable

Contains the grouping info.

classmethod read(filename, hdu='GTI')[source]#

Read from FITS file.

Parameters
filenamepathlib.Path, str

Filename

hdustr

hdu name. Default GTI.

select_time(time_interval)[source]#

Select and crop GTIs in time interval.

Parameters
time_intervalastropy.time.Time

Start and stop time for the selection.

Returns
gtiGTI

Copy of the GTI table with selection applied.

stack(other)[source]#

Stack with another GTI in place.

This simply changes the time reference of the second GTI table and stack the two tables. No logic is applied to the intervals.

Parameters
otherGTI

GTI to stack to self

to_table_hdu(format='gadf')[source]#

Convert this GTI instance to a astropy.io.fits.BinTableHDU.

Parameters
format: str

Output format, currently only “gadf” is supported

Returns
hdu: astropy.io.fits.BinTableHDU

GTI table converted to FITS representation

union(overlap_ok=True, merge_equal=True)[source]#

Union of overlapping time intervals.

Returns a new GTI object.

Parameters
overlap_okbool

Whether to raise an error when overlapping time bins are found.

merge_equalbool

Whether to merge touching time bins e.g. (1, 2) and (2, 3) will result in (1, 3).

write(filename, **kwargs)[source]#

Write to file.

Parameters
filenamestr or Path

File name to write to.