def test_calc_sky_only(gain, aperture_area):
# The sky noise per pixel is the poisson and per pixel.
sky = 10
expected = np.sqrt(gain * aperture_area * sky)
np.testing.assert_allclose(
calculate_noise(gain=gain,
aperture_area=aperture_area,
sky_per_pix=sky), expected)
def test_calc_noise_source_only(gain, aperture_area):
# If the only source of noise is Poisson error in the source
# then the noise should be the square root of the counts.
counts = 100
expected = np.sqrt(gain * counts)
np.testing.assert_allclose(
calculate_noise(gain=gain, flux=counts, aperture_area=aperture_area),
expected)
def test_calc_read_noise_only(gain, aperture_area):
# The read noise per pixel IS the noise. The only multiplier is
# the number of pixels.
read_noise = 10
expected = np.sqrt(aperture_area * read_noise**2)
np.testing.assert_allclose(
calculate_noise(gain=gain,
read_noise=read_noise,
aperture_area=aperture_area), expected)
def test_calc_noise_dark_only(gain, aperture_area):
# Gain should not affect this one. Dark current needs a couple other things,
# but this is basically Poisson error.
dark_current = 10
exposure = 20
expected = np.sqrt(dark_current * aperture_area * exposure)
np.testing.assert_allclose(
calculate_noise(gain=gain,
dark_current_per_sec=dark_current,
aperture_area=aperture_area,
exposure=exposure), expected)
def test_annulus_area_term():
# Test that noise is correct with an annulus
aperture_area = 20
# Annulus is typically quite a bit larger than aperture.
annulus_area = 10 * aperture_area
gain = 1.5
sky = 10
expected = np.sqrt(gain * aperture_area *
(1 + aperture_area / annulus_area) * sky)
np.testing.assert_allclose(
calculate_noise(gain=gain,
aperture_area=aperture_area,
annulus_area=annulus_area,
sky_per_pix=sky), expected)
def test_calc_noise_messy_case(digit, expected):
# Do a single test where all the parameters are set and compare with
# what a calculator gave.
counts = 1000
aperture_area = 20
annulus_area = 10 * aperture_area
gain = 1.5
sky = 15
dark_current = 7
exposure = 18
read_noise = 12
np.testing.assert_allclose(
calculate_noise(flux=counts,
gain=gain,
dark_current_per_sec=dark_current,
read_noise=read_noise,
sky_per_pix=sky,
exposure=exposure,
aperture_area=aperture_area,
annulus_area=annulus_area,
include_digitization=digit), expected)
def test_calc_noise_defaults():
# If we put in nothing we should get zero back
assert calculate_noise() == 0