Note

You are not reading the most up to date version of Gammapy documentation.
Access the latest stable version v1.3 or the list of Gammapy releases.

ReflectedRegionsFinder

class gammapy.background.ReflectedRegionsFinder(region, center, angle_increment='0.1 rad', min_distance='0 rad', min_distance_input='0.1 rad', max_region_number=10000, exclusion_mask=None, binsz='0.02 deg')

Bases: object

Find reflected regions.

This class is responsible for placing Reflected regions for a given input region and pointing position. It converts to pixel coordinates internally. At the moment it works only for circles. If you want to make a background estimate for an IACT observation using the reflected regions method, see also ReflectedRegionsBackgroundEstimator

Parameters:

region : CircleSkyRegion

Region to rotate

center : SkyCoord

Rotation point

angle_increment : Angle, optional

Rotation angle applied when a region falls in an excluded region.

min_distance : Angle, optional

Minimal distance between to reflected regions

min_distance_input : Angle, optional

Minimal distance from input region

max_region_number : int, optional

Maximum number of regions to use

exclusion_mask : WcsNDMap, optional

Exclusion mask

binsz : Angle

Bin size of the reference map used for region finding. Default : 0.02 deg

Examples

>>>

>>> from astropy.coordinates import SkyCoord, Angle
>>> from regions import CircleSkyRegion
>>> from gammapy.background import ReflectedRegionsFinder
>>> pointing = SkyCoord(83.2, 22.7, unit='deg', frame='icrs')
>>> target_position = SkyCoord(80.2, 23.5, unit='deg', frame='icrs')
>>> theta = Angle(0.4, 'deg')
>>> on_region = CircleSkyRegion(target_position, theta)
>>> finder = ReflectedRegionsFinder(min_distance_input='1 rad', region=on_region, center=pointing)
>>> finder.run()
>>> print(finder.reflected_regions[0])
Region: CircleSkyRegion
center: <SkyCoord (Galactic): (l, b) in deg
    ( 184.9367087, -8.37920222)>
    radius: 0.400147197682 deg

Methods Summary

find_regions(self)	Find reflected regions.
make_reference_map(region, center[, binsz])	Create empty reference map.
plot(self[, fig, ax])	Standard debug plot.
run(self)	Run all steps.
setup(self)	Compute parameters for reflected regions algorithm.

Methods Documentation

find_regions(self)

Find reflected regions.

static make_reference_map(region, center, binsz='0.02 deg')

Create empty reference map.

The size of the mask is chosen such that all reflected region are contained on the image.

Parameters:

region : CircleSkyRegion

Region to rotate

center : SkyCoord

Rotation point

binsz : Angle

Reference map bin size. Default : 0.02 deg

plot(self, fig=None, ax=None)

Standard debug plot.

See example here: :ref:’regions_reflected’.

run(self)

Run all steps.

setup(self)

Compute parameters for reflected regions algorithm.