FixedPointingInfo

class gammapy.data.FixedPointingInfo(meta=None, mode=None, fixed_icrs=None, fixed_altaz=None, location=None, time_start=None, time_stop=None, time_ref=None, legacy_altaz=None)

Bases: object

IACT array pointing info.

Data format specification: POINTING

Parameters

metameta

Meta header info from Table on pointing. Passing this is deprecated, provide mode and fixed_icrs or fixed_altaz instead or use FixedPointingInfo.from_fits_header instead.

modePointingMode

How the telescope was pointing during the observation

fixed_icrsSkyCoord in ICRS frame

Mandatory if mode is PointingMode.POINTING, the ICRS coordinates that are fixed for the duration of the observation.

fixed_altazSkyCoord in AltAz frame

Mandatory if mode is PointingMode.DRIFT, the AltAz coordinates that are fixed for the duration of the observation.

Examples

>>> from gammapy.data import FixedPointingInfo, PointingMode
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> fixed_icrs = SkyCoord(83.633 * u.deg, 22.014 * u.deg, frame="icrs")
>>> pointing_info = FixedPointingInfo(mode=PointingMode.POINTING, fixed_icrs=fixed_icrs)
>>> print(pointing_info)
FixedPointingInfo:

mode:        PointingMode.POINTING
coordinates: <SkyCoord (ICRS): (ra, dec) in deg
    (83.633, 22.014)>

Attributes Summary

altaz	Deprecated since version 1.1.
altaz_frame	Deprecated since version 1.1.
duration	Deprecated since version 1.1.
fixed_altaz	The fixed coordinates in AltAz of the observation.
fixed_icrs	The fixed coordinates in ICRS of the observation.
location	Deprecated since version 1.1.
meta	Deprecated since version 1.1.
mode	See PointingMode, if not present, assume POINTING
obstime	Deprecated since version 1.1.
radec	Deprecated since version 1.1.
time_ref	Deprecated since version 1.1.
time_start	Deprecated since version 1.1.
time_stop	Deprecated since version 1.1.

Methods Summary

from_fits_header(header)	Parse FixedPointingInfo from the given fits header
get_altaz([obstime, location])	Get the pointing position in AltAz frame for a given time.
get_icrs([obstime, location])	Get the pointing position in ICRS frame for a given time.
read(filename[, hdu])	Read pointing information table from file to obtain the metadata.
to_fits_header([format, version, time_ref])	Convert this FixedPointingInfo object into a fits header for the given format

Attributes Documentation

altaz

Deprecated since version 1.1: The altaz function is deprecated and may be removed in a future version.

ALT/AZ pointing position computed from RA/DEC (SkyCoord) for the midpoint of the run.

Use get_altaz to get the pointing at a specific time, correctly handling different pointing modes.

altaz_frame

Deprecated since version 1.1: The altaz_frame function is deprecated and may be removed in a future version.

ALT / AZ frame (AltAz).

duration

Deprecated since version 1.1: The duration function is deprecated and may be removed in a future version.

Pointing duration (TimeDelta).

The time difference between the TSTART and TSTOP.

fixed_altaz

The fixed coordinates in AltAz of the observation.

None if not a DRIFT observation

fixed_icrs

The fixed coordinates in ICRS of the observation.

None if not a POINTING observation

location

Deprecated since version 1.1: The location function is deprecated and may be removed in a future version.

Observatory location (EarthLocation).

meta

Deprecated since version 1.1: The meta function is deprecated and may be removed in a future version.

mode

See PointingMode, if not present, assume POINTING

obstime

Deprecated since version 1.1: The obstime function is deprecated and may be removed in a future version.

Average observation time for the observation (Time).

radec

Deprecated since version 1.1: The radec function is deprecated and may be removed in a future version.

RA/DEC pointing position from table (SkyCoord).

Use get_icrs to get the pointing at a specific time, correctly handling different pointing modes.

time_ref

Deprecated since version 1.1: The time_ref function is deprecated and may be removed in a future version.

Reference time (Time).

time_start

Deprecated since version 1.1: The time_start function is deprecated and may be removed in a future version.

Start time (Time).

time_stop

Deprecated since version 1.1: The time_stop function is deprecated and may be removed in a future version.

Stop time (Time).

Methods Documentation

classmethod from_fits_header(header)

Parse FixedPointingInfo from the given fits header

Parameters

headerastropy.fits.Header

Header to parse, e.g. from a GADF EVENTS HDU. Currently, only GADF is supported.

Returns

pointing: FixedPointingInfo

The FixedPointingInfo instance filled from the given header

get_altaz(obstime=None, location=None) → astropy.coordinates.sky_coordinate.SkyCoord

Get the pointing position in AltAz frame for a given time.

If the observation was performed tracking a fixed position in ICRS, the icrs pointing is transformed at the given time using the location of the observation.

If the observation was performed in drift mode, the fixed altaz coordinate is returned with obstime attached.

Parameters

obstime: `astropy.time.Time`

Time for which to get the pointing position in AltAz frame

location: `astropy.coordinates.EarthLocation`

Observatory location, only needed for pointing observations to transform from ICRS to horizontal coordinates.

get_icrs(obstime=None, location=None) → astropy.coordinates.sky_coordinate.SkyCoord

Get the pointing position in ICRS frame for a given time.

If the observation was performed tracking a fixed position in ICRS, the icrs pointing is returned with the given obstime attached.

If the observation was performed in drift mode, the fixed altaz coordinates are transformed to ICRS using the observation location and the given time.

Parameters

obstime: `astropy.time.Time`

Time for which to get the pointing position in ICRS frame

location: `astropy.coordinates.EarthLocation`

Observatory location, only needed for drift observations to transform from horizontal coordinates to ICRS.

classmethod read(filename, hdu='EVENTS')

Read pointing information table from file to obtain the metadata.

Parameters

filenamestr

File name

hduint or str

HDU number or name

Returns

pointing_infoPointingInfo

Pointing info object

to_fits_header(format='gadf', version='0.3', time_ref=None)

Convert this FixedPointingInfo object into a fits header for the given format

Parameters

formatstr

Format, currently only “gadf” is supported

versionstr

Version of the format, this function currently supports gadf versions 0.2 and 0.3.

time_refastropy.time.Time or None

Reference time for storing the time related information in fits format

Returns

headerastropy.fits.Header

Header with fixed pointing information filled for the requested format