ReflectedRegionsFinder

class gammapy.makers.ReflectedRegionsFinder(angle_increment='0.1 rad', min_distance='0 rad', min_distance_input='0.1 rad', max_region_number=10000, binsz='0.01 deg')

Bases: gammapy.makers.background.reflected.RegionsFinder

Find reflected regions.

This class is responsible for placing a reflected region for a given input region and pointing position. It converts to pixel coordinates internally assuming a tangent projection at center position.

If the center lies inside the input region, no reflected regions can be found.

If you want to make a background estimate for an IACT observation using the reflected regions method, see also ReflectedRegionsBackgroundMaker.

Parameters

angle_incrementAngle, optional

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

min_distanceAngle, optional

Minimum rotation angle between two consecutive reflected regions.

min_distance_inputAngle, optional

Minimum rotation angle between the input region and the first reflected region.

max_region_numberint, optional

Maximum number of regions to use.

binszAngle

Bin size of the reference map used for region finding.

Examples

>>> from astropy.coordinates import SkyCoord, Angle
>>> from regions import CircleSkyRegion
>>> from gammapy.makers 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')
>>> regions, wcs = finder.run(region=on_region, center=pointing)
>>> print(regions[0]) 
Region: CircleSkyRegion
center: <SkyCoord (ICRS): (ra, dec) in deg
    (83.19879005, 25.57300957)>
radius: 1438.3... arcsec

Create a new RegionFinder.

Methods Summary

run(region, center[, exclusion_mask])

Find reflected regions.

Methods Documentation

run(region, center, exclusion_mask=None)

Find reflected regions.

Parameters

regionSkyRegion

Region to rotate.

centerSkyCoord

Rotation point.

exclusion_maskWcsNDMap, optional

Exclusion mask. Regions intersecting with this mask will not be included in the returned regions. Default is None.

Returns

regionslist of SkyRegion

Reflected regions.

wcsWCS

WCS for the determined regions.