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background_error¶

gammapy.stats.background_error(n_off, alpha)[source]¶

Estimate standard error on background in the on region from an off-region observation.

$\Delta\mu_{bkg} = \alpha \times \sqrt{n_{off}}$

Parameters

n_offarray_like: Observed number of counts in the off region
alphaarray_like: On / off region exposure ratio for background events

Returns

backgroundnumpy.ndarray: Background estimate for the on region

Examples

>>>>>> background_error(n_off=4, alpha=0.1)
0.2
>>> background_error(n_off=9, alpha=0.2)
0.6