AdaptiveRingBackgroundEstimator

class gammapy.background.AdaptiveRingBackgroundEstimator(r_in, r_out_max, width, stepsize='0.02 deg', threshold_alpha=0.1, theta='0.22 deg', method='fixed_width')[source]

Bases: object

Adaptive ring background algorithm.

This algorithm extends the RingBackgroundEstimator method by adapting the size of the ring to achieve a minimum on / off exposure ratio (alpha) in regions where the area to estimate the background from is limited.

Parameters:
r_in : Quantity

Inner radius of the ring.

r_out_max : Quantity

Maximal outer radius of the ring.

width : Quantity

Width of the ring.

stepsize : Quantity

Stepsize used for increasing the radius.

threshold_alpha : float

Threshold on alpha above which the adaptive ring takes action.

theta : Quantity

Integration radius used for alpha computation.

method : {‘fixed_width’, ‘fixed_r_in’}

Adaptive ring method.

See also

RingBackgroundEstimator, gammapy.detect.KernelBackgroundEstimator

Examples

Example using AdaptiveRingBackgroundEstimator:

from gammapy.maps import Map
from gammapy.background import AdaptiveRingBackgroundEstimator

filename = '$GAMMAPY_DATA/tests/unbundled/poisson_stats_image/input_all.fits.gz'
images = {
    'counts': Map.read(filename, hdu='counts'),
    'exposure_on': Map.read(filename, hdu='exposure'),
    'exclusion': Map.read(filename, hdu='exclusion'),
}

adaptive_ring_bkg = AdaptiveRingBackgroundEstimator(
    r_in='0.22 deg',
    r_out_max='0.8 deg',
    width='0.1 deg',
)
results = adaptive_ring_bkg.run(images)
results['background'].plot()

Attributes Summary

parameters Parameter dict.

Methods Summary

kernels(image) Ring kernels according to the specified method.
run(images) Run adaptive ring background algorithm.

Attributes Documentation

parameters

Parameter dict.

Methods Documentation

kernels(image)[source]

Ring kernels according to the specified method.

Parameters:
image : WcsNDMap

Map specifying the WCS information.
Returns:
kernels : list

List of Ring2DKernel
run(images)[source]

Run adaptive ring background algorithm.

Parameters:
images : dict of WcsNDMap

Input sky maps.
Returns:
result : dict of WcsNDMap

Result sky maps.