def contrast_limit(path_images, path_psf, noise, mask, parang, psf_scaling,
extra_rot, pca_number, threshold, aperture, residuals,
snr_inject, position):
"""
Function for calculating the contrast limit at a specified position for a given sigma level or
false positive fraction, both corrected for small sample statistics.
Parameters
----------
path_images : str
System location of the stack of images (3D).
path_psf : str
System location of the PSF template for the fake planet (3D). Either a single image or a
stack of images equal in size to science data.
noise : numpy.ndarray
Residuals of the PSF subtraction (3D) without injection of fake planets. Used to measure
the noise level with a correction for small sample statistics.
mask : numpy.ndarray
Mask (2D).
parang : numpy.ndarray
Derotation angles (deg).
psf_scaling : float
Additional scaling factor of the planet flux (e.g., to correct for a neutral density
filter). Should have a positive value.
extra_rot : float
Additional rotation angle of the images in clockwise direction (deg).
pca_number : int
Number of principal components used for the PSF subtraction.
threshold : tuple(str, float)
Detection threshold for the contrast curve, either in terms of "sigma" or the false
positive fraction (FPF). The value is a tuple, for example provided as ("sigma", 5.) or
("fpf", 1e-6). Note that when sigma is fixed, the false positive fraction will change with
separation. Also, sigma only corresponds to the standard deviation of a normal distribution
at large separations (i.e., large number of samples).
aperture : float
Aperture radius (pix) for the calculation of the false positive fraction.
residuals : str
Method used for combining the residuals ("mean", "median", "weighted", or "clipped").
position : tuple(float, float)
The separation (pix) and position angle (deg) of the fake planet.
snr_inject : float
Signal-to-noise ratio of the injected planet signal that is used to measure the amount
of self-subtraction.
Returns
-------
NoneType
None
"""
images = np.load(path_images)
psf = np.load(path_psf)
if threshold[0] == "sigma":
sigma = threshold[1]
# Calculate the FPF for a given sigma level
fpf = student_t(t_input=threshold,
radius=position[0],
size=aperture,
ignore=False)
elif threshold[0] == "fpf":
fpf = threshold[1]
# Calculate the sigma level for a given FPF
sigma = student_t(t_input=threshold,
radius=position[0],
size=aperture,
ignore=False)
else:
raise ValueError("Threshold type not recognized.")
# Cartesian coordinates of the fake planet
xy_fake = polar_to_cartesian(images, position[0], position[1] - extra_rot)
# Determine the noise level
_, t_noise, _, _ = false_alarm(image=noise[0, ],
x_pos=xy_fake[0],
y_pos=xy_fake[1],
size=aperture,
ignore=False)
# Aperture properties
im_center = center_subpixel(images)
ap_dict = {
'type': 'circular',
'pos_x': im_center[1],
'pos_y': im_center[0],
'radius': aperture
}
# Measure the flux of the star
phot_table = aperture_photometry(psf_scaling * psf[0, ],
create_aperture(ap_dict),
method='exact')
star = phot_table['aperture_sum'][0]
# Magnitude of the injected planet
flux_in = snr_inject * t_noise
mag = -2.5 * math.log10(flux_in / star)
# Inject the fake planet
fake = fake_planet(images=images,
psf=psf,
parang=parang,
position=(position[0], position[1]),
magnitude=mag,
psf_scaling=psf_scaling)
# Run the PSF subtraction
_, im_res = pca_psf_subtraction(images=fake * mask,
angles=-1. * parang + extra_rot,
pca_number=pca_number)
# Stack the residuals
im_res = combine_residuals(method=residuals, res_rot=im_res)
# Measure the flux of the fake planet
flux_out, _, _, _ = false_alarm(image=im_res[0, ],
x_pos=xy_fake[0],
y_pos=xy_fake[1],
size=aperture,
ignore=False)
# Calculate the amount of self-subtraction
attenuation = flux_out / flux_in
# Calculate the detection limit
contrast = sigma * t_noise / (attenuation * star)
# The flux_out can be negative, for example if the aperture includes self-subtraction regions
if contrast > 0.:
contrast = -2.5 * math.log10(contrast)
else:
contrast = np.nan
# Separation [pix], position antle [deg], contrast [mag], FPF
return position[0], position[1], contrast, fpf
def paco_contrast_limit(path_images, path_psf, noise, parang, psf_rad,
psf_scaling, res_scaling, pixscale, extra_rot,
threshold, aperture, snr_inject, position, algorithm):
"""
Function for calculating the contrast limit at a specified position for a given sigma level or
false positive fraction, both corrected for small sample statistics.
Parameters
----------
path_images : str
System location of the stack of images (3D).
path_psf : str
System location of the PSF template for the fake planet (3D). Either a single image or a
stack of images equal in size to science data.
noise : numpy.ndarray
Residuals of the PSF subtraction (3D) without injection of fake planets. Used to measure
the noise level with a correction for small sample statistics.
parang : numpy.ndarray
Derotation angles (deg).
psf_scaling : float
Additional scaling factor of the planet flux (e.g., to correct for a neutral density
filter). Should have a positive value.
extra_rot : float
Additional rotation angle of the images in clockwise direction (deg).
threshold : tuple(str, float)
Detection threshold for the contrast curve, either in terms of "sigma" or the false
positive fraction (FPF). The value is a tuple, for example provided as ("sigma", 5.) or
("fpf", 1e-6). Note that when sigma is fixed, the false positive fraction will change with
separation. Also, sigma only corresponds to the standard deviation of a normal distribution
at large separations (i.e., large number of samples).
aperture : float
Aperture radius (pix) for the calculation of the false positive fraction.
position : tuple(float, float)
The separation (pix) and position angle (deg) of the fake planet.
snr_inject : float
Signal-to-noise ratio of the injected planet signal that is used to measure the amount
of self-subtraction.
Returns
-------
NoneType
None
"""
images = np.load(path_images)
psf = np.load(path_psf)
if threshold[0] == "sigma":
sigma = threshold[1]
# Calculate the FPF for a given sigma level
fpf = student_t(t_input=threshold,
radius=position[0],
size=aperture,
ignore=False)
elif threshold[0] == "fpf":
fpf = threshold[1]
# Calculate the sigma level for a given FPF
sigma = student_t(t_input=threshold,
radius=position[0],
size=aperture,
ignore=False)
else:
raise ValueError("Threshold type not recognized.")
# Cartesian coordinates of the fake planet
xy_fake = polar_to_cartesian(images, position[0], position[1] - extra_rot)
# Determine the noise level
_, t_noise, _, _ = false_alarm(image=noise,
x_pos=xy_fake[0],
y_pos=xy_fake[1],
size=aperture,
ignore=False)
# Aperture properties
im_center = center_subpixel(images)
# Measure the flux of the star
ap_phot = CircularAperture((im_center[1], im_center[0]), aperture)
phot_table = aperture_photometry(psf_scaling * psf[0, ],
ap_phot,
method='exact')
star = phot_table['aperture_sum'][0]
# Magnitude of the injected planet
flux_in = snr_inject * t_noise
mag = -2.5 * math.log10(flux_in / star)
# Inject the fake planet
fake = fake_planet(images=images,
psf=psf,
parang=parang,
position=(position[0], position[1]),
magnitude=mag,
psf_scaling=psf_scaling)
path_fake_planet = os.path.split(path_images)[0] = "/"
np.save(path_fake_planet + "injected.npy", fake)
# Run the PSF subtraction
#_, im_res = pca_psf_subtraction(images=fake*mask,
# angles=-1.*parang+extra_rot,
# pca_number=pca_number)
# Stack the residuals
#im_res = combine_residuals(method=residuals, res_rot=im_res)
# Measure the flux of the fake planet
#flux_out, _, _, _ = false_alarm(image=im_res[0, ],
# x_pos=xy_fake[0],
# y_pos=xy_fake[1],
# size=aperture,
# ignore=False)
# Setup PACO
if algorithm == "fastpaco":
fp = FastPACO(image_file=path_fake_planet + "injected.npy",
angles=parang,
psf=psf,
psf_rad=psf_rad,
px_scale=pixscale,
res_scale=res_scaling,
verbose=False)
elif algorithm == "fullpaco":
fp = FullPACO(image_file=path_fake_planet + "injected.npy",
angles=parang,
psf=psf,
psf_rad=psf_rad,
px_scale=pixscale,
res_scale=res_scaling,
verbose=False)
# Run PACO
# Restrict to 1 processor since this module is called from a child process
a, b = fp.PACO(cpu=1)
# Should do something with these?
snr = b / np.sqrt(a)
flux_residual = b / a
flux_out, _, _, _ = false_alarm(image=flux_residual,
x_pos=xy_fake[0],
y_pos=xy_fake[1],
size=aperture,
ignore=False)
# Iterative, unbiased flux estimation
# This doesn't seem to give the correct results yet?
#if self.m_flux_calc:
# phi0s = fp.thresholdDetection(snr,self.m_threshold)
# init = np.array([flux[int(phi0[0]),int(phi0[1])] for phi0 in phi0s])
# ests = np.array(fp.fluxEstimate(phi0s,self.m_eps,init))
# Calculate the amount of self-subtraction
attenuation = flux_out / flux_in
# Calculate the detection limit
contrast = sigma * t_noise / (attenuation * star)
# The flux_out can be negative, for example if the aperture includes self-subtraction regions
if contrast > 0.:
contrast = -2.5 * math.log10(contrast)
else:
contrast = np.nan
# Separation [pix], position antle [deg], contrast [mag], FPF
return (position[0], position[1], contrast, fpf)