def bkg_subtraction(time, flux, scope="tpf", sigma=3):
"""Subtracts background flux from target pixel file.
Parameters
----------
scope : string, "tpf" or "postcard"
If `tpf`, will use data from the target pixel file only to estimate and remove the background.
If `postcard`, will use data from the entire postcard region to estimate and remove the background.
sigma : float
The standard deviation cut used to determine which pixels are representative of the background in each cadence.
"""
tpf_flux_bkg = []
sigma_clip = SigmaClip(sigma=sigma)
# bkg = MMMBackground(sigma_clip=sigma_clip)
bkg = SExtractorBackground(sigma_clip=sigma_clip)
bkg_MMM = MMMBackground(sigma_clip=sigma_clip)
bkg_ModeEstimator = ModeEstimatorBackground(median_factor=3.,
mean_factor=2.,
sigma_clip=sigma_clip)
bkg_Mean = MeanBackground(sigma_clip)
bkg_Median = MedianBackground(sigma_clip)
bkg_SExtractor = SExtractorBackground(sigma_clip)
bkg_MMM_value = bkg_MMM.calc_background(flux[0])
bkg_ModeEstimator_value = bkg_ModeEstimator.calc_background(flux[0])
bkg_Mean_value = bkg_Mean.calc_background(flux[0])
bkg_Median_value = bkg_Median.calc_background(flux[0])
bkg_SExtractor_value = bkg_SExtractor.calc_background(flux[0])
print("MMM Background = {}".format(bkg_MMM_value))
print("ModeEstimator Background = {}".format(bkg_ModeEstimator_value))
print("Mean Background = {}".format(bkg_Mean_value))
print("Median Background = {}".format(bkg_Median_value))
print("SExtractor Background = {}".format(bkg_SExtractor_value))
for i in range(len(time)):
bkg_value = bkg.calc_background(flux[i])
tpf_flux_bkg.append(bkg_value)
tpf_flux_bkg = np.array(tpf_flux_bkg)
return tpf_flux_bkg
def bkg_estimation(filename,
box=(20, 20),
filter_size=(3, 3),
bkg_estimator='SExtractor',
sigma=3.,
sigma_lower=None,
sigma_upper=None,
maxiters=10,
outLevel=1):
imagelist = np.atleast_1d(filename)
for ima in imagelist:
print("\nEstimate background in %s" % ima)
root = os.path.splitext(ima)[0]
hdulist = fits.open(ima)
data = hdulist[0].data
sigma_clip = SigmaClip(sigma=sigma,
sigma_lower=sigma_lower,
sigma_upper=sigma_upper,
maxiters=maxiters)
if bkg_estimator == 'SExtractor':
bkg_estimator = SExtractorBackground()
elif bkg_estimator == 'MMM':
bkg_estimator = MMMBackground()
elif bkg_estimator == 'ModeEstimator':
bkg_estimator = ModeEstimatorBackground()
elif bkg_estimator == 'Median':
bkg_estimator = MedianBackground()
elif bkg_estimator == 'Mean':
bkg_estimator = MeanBackground()
bkg = Background2D(
data,
box,
filter_size=filter_size,
sigma_clip=sigma_clip,
bkg_estimator=bkg_estimator,
)
# Create image with background substracted
hdulist[0].data = data - bkg.background
hdulist.writeto(ima, overwrite=True)
if outLevel == 2:
# Create image with 2D background
bkg_file = root + "_bkg_map.fits"
hdulist[0].data = bkg.background
hdulist.writeto(bkg_file, overwrite=True)
def bkg_sub(img,
mask,
sigma=5,
bkg_estimator='median',
box=(10, 2),
filter_size=(1, 1)):
"""
Completes a step for fitting a 2D background
model.
Parameters
----------
img : np.ndarray
Single exposure frame.
mask : np.ndarray
Mask to remove the orders.
sigma : float, optional
Sigma to remove above. Default is 5.
bkg_estimator : str, optional
Which type of 2D background model to use.
Default is `median`.
box : tuple, optional
Box size by which to smooth over. Default
is (10,2) --> prioritizes smoothing by
column.
filter_size : tuple, optional
The window size of the 2D filter to apply to the
low-resolution background map. Default is (1,1).
Returns
-------
background : np.ndarray
The modeled background image.
"""
sigma_clip = SigmaClip(sigma=sigma)
if bkg_estimator.lower() == 'mmmbackground':
bkg = MMMBackground()
elif bkg_estimator.lower() == 'median':
bkg = MedianBackground()
b = Background2D(img,
box,
filter_size=filter_size,
bkg_estimator=bkg,
sigma_clip=sigma_clip,
fill_value=0.0,
mask=mask)
return b.background
def bkg_subtraction(self, scope="tpf", sigma=1.2):
"""Subtracts background flux from target pixel file.
Parameters
----------
scope : string, "tpf" or "postcard"
If `tpf`, will use data from the target pixel file only to estimate and remove the background.
If `postcard`, will use data from the entire postcard region to estimate and remove the background.
sigma : float
The standard deviation cut used to determine which pixels are representative of the background in each cadence.
"""
time = self.time
flux = self.bkg_tpf
self.tpf_flux_bkg = []
sigma_clip = SigmaClip(sigma=sigma)
bkg = MMMBackground(sigma_clip=sigma_clip)
for i in range(len(time)):
bkg_value = bkg.calc_background(flux[i])
self.tpf_flux_bkg.append(bkg_value)
self.tpf_flux_bkg = np.array(self.tpf_flux_bkg)
def subtract_sky_ccd_2d(ccd, skysub='SKYSUB', skyval='SKYVAL', box_size=(50,50), filter_size=(3,3), bkg_method='sextractor',
check_skysub=True, max_val=10000, fitsky=None, sigma=3., iters=10, edge_method='crop'):
# Although edge_method='pad' is recommended, it does give errors "total size of new array must be unchanged" for v0.3
if check_skysub and skysub is not None and skysub in ccd.header and ccd.header[skysub]:
return ccd
if not check_skysub and skysub is not None and skysub in ccd.header and ccd.header[skysub]:
print ('WARNING: Image already sky subtracted! Subtracting AGAIN the sky! [set check_skysub = True for checking]')
dsky = {'median': MedianBackground(), 'mean': MeanBackground(), 'sextractor': SExtractorBackground(),
'biweight': BiweightLocationBackground(), 'mode': ModeEstimatorBackground(), 'mm': MMMBackground()}
if not bkg_method in dsky:
print ('WARNING: Background type "%s" NOT available!! Selecting "median" from [%s]' % (bkg_type, ' | '.join(dksy.keys())))
bkg_estimator = dksy['median']
else:
bkg_estimator = dsky[bkg_method]
sigma_clip = SigmaClip(sigma=sigma, iters=iters) if sigma is not None and iters is not None else None
bkg = Background2D(ccd.data, box_size, filter_size=filter_size, sigma_clip=sigma_clip, bkg_estimator=bkg_estimator, edge_method=edge_method)
if max_val is not None and bkg.background_median >= max_val:
if 'FILENAME' in ccd.header:
print ('WARNING: File "%s" has high sky level (%s >= %s). Correction NOT applied' % (ccd.header['FILENAME'], bkg.background_median, max_val))
else:
print ('WARNING: File has high sky level (%s >= %s). Correction NOT applied' % (bkg.background_median, max_val))
return ccd
ccd.data -= bkg.background
ccd.header[skysub] = True
ccd.header[skyval] = bkg.background_median
ccd.header['SKYTYPE'] = '2D'
ccd.header['BKGTYPE'] = bkg_method
ccd.bkg = bkg
if fitsky is not None:
pyfits.writeto(fitsky, bkg.background, clobber=True)
return ccd
def __init__(self,
config: config.Config,
image: Union[str, np.ndarray],
input_table: Optional[Table] = None):
self.config = config
self.tables = TableSet(input_table)
self._image = None
self.image_name = 'unnamed'
if image is not None:
self.image = image
if config.use_catalogue_positions:
if self.tables.input_table is None:
raise ValueError(
'Need an input catalogue to if we want to use catalogue positions'
)
self.starfinder = DAOStarFinder(threshold=self.image_stats.threshold,
fwhm=config.fwhm_guess,
sigma_radius=config.sigma_radius,
sharplo=config.sharplo,
sharphi=config.sharphi,
roundlo=config.roundlo,
roundhi=config.roundhi,
exclude_border=config.exclude_border)
self.grouper = DAOGroup(config.separation_factor * config.fwhm_guess)
self.fitter = LevMarLSQFitter()
self.background = MMMBackground()
self.photometry = None
self.epsfstars: Optional[photutils.EPSFStars] = None
self.epsf: Optional[photutils.EPSFModel] = None
self.fwhm: Optional[float] = None
self.residual = None
def bkg(self):
sigma_clip = SigmaClip(sigma=3.)
bkg = MMMBackground(sigma_clip=sigma_clip)
b = bkg.calc_background(self.flux, axis=(1, 2))
return b
def psfphotometry(imagefile,
ra=None,
dec=None,
x=None,
y=None,
fwhm=5.0,
zp=0.0,
gain=1.0,
doDifferential=False,
xfield=None,
yfield=None,
xfirst=None,
yfirst=None):
hdulist = fits.open(imagefile)
header = fits.getheader(imagefile)
if x == None:
w = WCS(header)
x0, y0 = w.wcs_world2pix(ra, dec, 1)
gain = 1.0
else:
x0, y0 = x, y
if len(hdulist) > 3:
image = hdulist[1].data
elif len(hdulist) == 2:
image = hdulist[0].data
else:
image = hdulist[0].data
image_shape = image.shape
#daogroup = DAOGroup(crit_separation=8)
daogroup = DAOGroup(crit_separation=25)
mmm_bkg = MMMBackground()
#iraffind = IRAFStarFinder(threshold=2.0*mmm_bkg(image),
# fwhm=4.0)
fitter = LevMarLSQFitter()
gaussian_prf = IntegratedGaussianPRF(flux=1, sigma=1.7)
gaussian_prf.sigma.fixed = False
gaussian_prf.flux.fixed = False
psffile = imagefile.replace(".fits", ".psf")
fid = open(psffile, 'w')
if len(image_shape) == 3:
nhdu, xshape, yshape = image.shape
dateobs = utcparser(hdulist[0].header["UTCSTART"])
mjd = dateobs.mjd
if "KINCYCTI" in hdulist[0].header:
mjdall = mjd + np.arange(
nhdu) * hdulist[0].header["KINCYCTI"] / 86400.0
else:
mjdall = mjd + np.arange(
nhdu) * hdulist[0].header["EXPTIME"] / 86400.0
mjds, mags, magerrs, fluxes, fluxerrs = [], [], [], [], []
for jj in range(nhdu):
if np.mod(jj, 10) == 0:
print('PSF fitting: %d/%d' % (jj, nhdu))
image = hdulist[0].data[jj, :, :]
mjd = mjdall[jj]
n, median, std = sigma_clipped_stats(image, sigma=3.0)
daofind = DAOStarFinder(fwhm=2.0, threshold=2. * std)
#phot_obj = IterativelySubtractedPSFPhotometry(finder=daofind,
# group_maker=daogroup,
# bkg_estimator=mmm_bkg,
# psf_model=gaussian_prf,
# fitter=fitter,
# fitshape=(21, 21),
# niters=10)
image = image - np.median(image)
image_slice = np.zeros(image.shape)
slsize = 25
xmin = np.max([0, int(x0 - slsize)])
xmax = np.min([int(x0 + slsize), image.shape[0]])
ymin = np.max([0, int(y0 - slsize)])
ymax = np.min([int(y0 + slsize), image.shape[1]])
image_slice[ymin:ymax, xmin:xmax] = 1
if doDifferential:
xmin_f = np.max([0, int(xfield - slsize)])
xmax_f = np.min([int(xfield + slsize), image.shape[0]])
ymin_f = np.max([0, int(yfield - slsize)])
ymax_f = np.min([int(yfield + slsize), image.shape[1]])
image_slice[ymin_f:ymax_f, xmin_f:xmax_f] = 1
image = image * image_slice
if (xfirst is None) or (yfirst is None):
phot_obj = BasicPSFPhotometry(finder=daofind,
group_maker=daogroup,
psf_model=gaussian_prf,
fitter=fitter,
fitshape=(21, 21),
bkg_estimator=mmm_bkg)
phot_results = phot_obj(image)
else:
gaussian_prf = IntegratedGaussianPRF(flux=1, sigma=1.7)
gaussian_prf.sigma.fixed = False
gaussian_prf.flux.fixed = False
gaussian_prf.x_0.fixed = False
gaussian_prf.y_0.fixed = False
phot_obj = BasicPSFPhotometry(group_maker=daogroup,
psf_model=gaussian_prf,
fitter=fitter,
fitshape=(21, 21),
bkg_estimator=mmm_bkg)
pos = Table(names=['x_0', 'y_0'],
data=[[xfirst, xfield], [yfirst, yfield]])
phot_results_tmp = phot_obj(image, init_guesses=pos)
resimage = phot_obj.get_residual_image()
pos = Table(names=['x_0', 'y_0'], data=[[x0], [y0]])
gaussian_prf = IntegratedGaussianPRF(flux=1, sigma=1.7)
gaussian_prf.sigma.fixed = False
gaussian_prf.flux.fixed = False
gaussian_prf.x_0.fixed = True
gaussian_prf.y_0.fixed = True
phot_obj = BasicPSFPhotometry(group_maker=daogroup,
psf_model=gaussian_prf,
fitter=fitter,
fitshape=(7, 7),
bkg_estimator=mmm_bkg)
phot_results = phot_obj(resimage, init_guesses=pos)
phot_results = vstack([phot_results_tmp, phot_results])
#if True:
if False:
#sources = iraffind(image)
sources = daofind(image)
import matplotlib.pyplot as plt
positions = np.transpose(
(sources['ycentroid'], sources['xcentroid']))
apertures = CircularAperture(positions, r=4.)
fig, axs = plt.subplots(1, 2)
plt.axes(axs[0])
plt.imshow(image.T,
origin='lower',
cmap='viridis',
aspect=1,
interpolation='nearest',
vmin=np.percentile(image[image > 0], 10),
vmax=np.percentile(image[image > 0], 90))
apertures.plot(color='red')
plt.xlim([ymin, ymax])
plt.ylim([xmin, xmax])
resimage = phot_obj.get_residual_image()
plt.axes(axs[1])
plt.imshow(resimage.T,
origin='lower',
cmap='viridis',
aspect=1,
interpolation='nearest',
vmin=0,
vmax=np.percentile(resimage[resimage > 0], 90))
apertures.plot(color='red')
plt.xlim([ymin, ymax])
plt.ylim([xmin, xmax])
plt.savefig('test_%d.png' % jj)
plt.close()
fig, axs = plt.subplots(1, 2)
plt.axes(axs[0])
plt.imshow(image.T,
origin='lower',
cmap='viridis',
aspect=1,
interpolation='nearest',
vmin=np.percentile(image[image > 0], 10),
vmax=np.percentile(image[image > 0], 90))
apertures.plot(color='red')
plt.xlim([ymin_f, ymax_f])
plt.ylim([xmin_f, xmax_f])
resimage = phot_obj.get_residual_image()
plt.axes(axs[1])
plt.imshow(resimage.T,
origin='lower',
cmap='viridis',
aspect=1,
interpolation='nearest',
vmin=np.percentile(resimage[resimage > 0], 10),
vmax=np.percentile(resimage[resimage > 0], 90))
apertures.plot(color='red')
plt.xlim([ymin_f, ymax_f])
plt.ylim([xmin_f, xmax_f])
plt.savefig('test_f_%d.png' % jj)
plt.close()
#phot_results.pprint_all()
#print(stop)
dist = np.sqrt((phot_results["x_fit"] - x0)**2 +
(phot_results["y_fit"] - y0)**2)
idx = np.argmin(dist)
flux = phot_results[idx]["flux_fit"]
fluxerr = phot_results[idx]["flux_unc"]
magerr = 1.0857 * fluxerr / flux #1.0857 = 2.5/log(10)
mag = zp - 2.5 * np.log10(flux)
if doDifferential:
dist = np.sqrt((phot_results["x_fit"] - xfield)**2 +
(phot_results["y_fit"] - yfield)**2)
idy = np.argmin(dist)
flux_field = phot_results[idy]["flux_fit"]
fluxerr_field = phot_results[idy]["flux_unc"]
magerr_field = 1.0857 * fluxerr_field / flux_field #1.0857 = 2.5/log(10)
mag_field = zp - 2.5 * np.log10(flux_field)
mag = mag - mag_field
magerr = np.sqrt(magerr**2 + magerr_field**2)
fluxerr = np.sqrt((fluxerr / flux)**2 +
(fluxerr_field / flux_field)**2)
flux = flux / flux_field
fluxerr = flux * fluxerr
#print(phot_results[idy]["flux_fit"], phot_results[idx]["flux_fit"])
mjds.append(mjd)
mags.append(mag)
magerrs.append(magerr)
fluxes.append(flux)
fluxerrs.append(fluxerr)
fid.write('%.5f %.5f %.5f %.5f %.5f\n' %
(dateobs.mjd, mag, magerr, flux, fluxerr))
fid.close()
return np.array(mjds), np.array(mags), np.array(magerrs), np.array(
fluxes), np.array(fluxerrs)
else:
mjds, mags, magerrs, fluxes, fluxerrs = [], [], [], [], []
for ii, hdu in enumerate(hdulist):
if ii == 0: continue
header = hdulist[ii].header
image = hdulist[ii].data
if not "DATE" in header:
print("Warning: 'DATE missing from %s hdu %d/%d" %
(imagefile, ii, len(hdulist)))
continue
dateobs = Time(header["DATE"])
phot_results = phot_obj(image)
dist = np.sqrt((phot_results["x_fit"] - x0)**2 +
(phot_results["y_fit"] - y0)**2)
idx = np.argmin(dist)
flux = phot_results[idx]["flux_fit"]
fluxerr = phot_results[idx]["flux_unc"]
magerr = 1.0857 * fluxerr / flux #1.0857 = 2.5/log(10)
mag = zp - 2.5 * np.log10(flux)
mjds.append(dateobs.mjd)
mags.append(mag)
magerrs.append(magerr)
fluxes.append(flux)
fluxerrs.append(fluxerr)
fid.write('%.5f %.5f %.5f %.5f %.5f\n' %
(dateobs.mjd, mag, magerr, flux, fluxerr))
fid.close()
return np.array(mjds), np.array(mags), np.array(magerrs), np.array(
fluxes), np.array(fluxerrs)
nrc.detector = 'NRCB5'
else:
nrc.detector = hdu[0].header['DETECTOR'] #'NRCA3'
#nrc_grid = nrc.psf_grid(num_psfs=9, all_detectors=False)
nrc_grid = nrc.psf_grid(num_psfs=25,
all_detectors=False,
fov_pixels=33,
oversample=2)
eval_xshape = int(np.ceil(nrc_grid.data.shape[2] / nrc_grid.oversampling))
eval_yshape = int(np.ceil(nrc_grid.data.shape[1] / nrc_grid.oversampling))
# And now, let's run the PSF Photometry
sigma_psf = 3.
daogroup = DBSCANGroup(2.0 * sigma_psf * gaussian_sigma_to_fwhm)
mmm_bkg = MMMBackground()
fit_shape = (eval_yshape, eval_xshape)
phot = BasicPSFPhotometry(daogroup,
mmm_bkg,
nrc_grid,
fit_shape,
finder=None,
aperture_radius=3.)
# This is the part that takes the longest, so I print out the date/time before and after.
now = datetime.now()
dt_string = now.strftime("%d/%m/%Y %H:%M:%S")
print("Starting the fit: date and time = ", dt_string)
tbl = phot(data, init_guesses=init_tbl)
def bkg(flux, sigma=2.5):
# Returns background for a single cadence. Default sigma=2.5
sigma_clip = SigmaClip(sigma=sigma)
bkg = MMMBackground(sigma_clip=sigma_clip)
return bkg.calc_background(flux)
dec = float(target[0]['dec'])
coord = SkyCoord(ra, dec, unit='deg')
ahdu = search_tesscut(coord, sector=args.Sector).download(cutout_size=args.size, download_dir='.')
#w = WCS(allhdus.hdu[2].header)
hdu = ahdu.hdu
flux = hdu[1].data['FLUX']
bkgs = np.zeros(len(flux))
#Background
for i,f in enumerate(flux):
sigma_clip = SigmaClip(sigma=3)
bkg = MMMBackground(sigma_clip=sigma_clip)
bkgs[i] = bkg.calc_background(f)
#flux = np.log10(np.abs(np.nanmin(flux)) + flux + 1)
time = hdu[1].data['TIME'] + hdu[1].header['BJDREFI']
def animate(i, fig, ax, flux, time, start=0):
#ax.text(0.98, 0.98, time[i], transform=ax.transAxes, color='white', ha='right', va='top')
#im = ax.matshow(flux[i+start], cmap=plt.cm.YlGnBu_r)
im.set_array(flux[i+start])
te.set_text('%.4f' % time[i+start])
return im, te
fig, ax = plt.subplots(figsize=[2,2])
ax.set_xticks([])
img_tight, table = read_or_generate_image('tight8group', recipe=recipe)
guess_table_tight = prepare_table(table)
fit_stages_tight = [FitStage(10, 0.001, 0.001, np.inf, all_individual), # first stage: flux is wildly off, get decent guess
FitStage(10, 2., 2., 50_000, all_individual),
FitStage(10, 1., 1., 20_000, brightest_simultaneous(3)),
FitStage(10, 1., 1., 20_000, brightest_simultaneous(5)),
FitStage(10, 0.5, 0.5, np.inf, all_simultaneous),
FitStage(50, 0.2, 0.2, 10_000, all_simultaneous)
]
# %%
photometry_tight = IncrementalFitPhotometry(MMMBackground(),
model,
max_group_size=100,
group_extension_radius=10,
fit_stages=fit_stages_tight)
result_table_tight = photometry_tight.do_photometry(img_tight, guess_table_tight)
# %%
figure()
residual = photometry_tight.residual(result_table_tight)
imshow(residual[400:600,400:600])
colorbar()
np.max(img_tight)
# %%
def psf_fit(data_array, data_file, psf_grid, fheader, imagemodel):
# Let's run a quick fitting using DAOStarFinder
mean, median, std = sigma_clipped_stats(data_array, sigma=3.0)
daofind = DAOStarFinder(fwhm=3.0, threshold=5. * std)
sources = daofind(data_array - median)
# And now, let's make some cuts to remove objects that are too faint or too bright
flux_min = 5 #5 #0
flux_max = 50 #50 #1000
flux_range = np.where((sources['flux'] > flux_min)
& (sources['flux'] < flux_max))[0]
init_tbl = Table()
init_tbl['x_0'] = sources['xcentroid'][flux_range]
init_tbl['y_0'] = sources['ycentroid'][flux_range]
init_tbl['flux_0'] = sources['flux'][flux_range]
# And now, let's make a plot of the original image.
plt.figure(figsize=(9, 9))
imshow_norm(data_array,
interval=PercentileInterval(99.),
stretch=SqrtStretch())
plt.colorbar()
plt.savefig(data_file + '.png', dpi=300)
plt.clf()
# And now, let's make a plot of the image showing the positions of the objects.
plt.figure(figsize=(9, 9))
imshow_norm(data_array,
interval=PercentileInterval(99.),
stretch=SqrtStretch())
plt.scatter(init_tbl['x_0'], init_tbl['y_0'], s=10, color='black')
plt.colorbar()
plt.savefig(data_file + '_with_daostarfinder_objects.png', dpi=300)
plt.clf()
eval_xshape = int(np.ceil(psf_grid.data.shape[2] / psf_grid.oversampling))
eval_yshape = int(np.ceil(psf_grid.data.shape[1] / psf_grid.oversampling))
# And now, let's run the PSF Photometry
sigma_psf = 3.
daogroup = DBSCANGroup(2.0 * sigma_psf * gaussian_sigma_to_fwhm)
mmm_bkg = MMMBackground()
fit_shape = (eval_yshape, eval_xshape)
phot = BasicPSFPhotometry(daogroup,
mmm_bkg,
psf_grid,
fit_shape,
finder=None,
aperture_radius=3.)
# This is the part that takes the longest, so I print out the date/time before and after.
now = datetime.now()
dt_string = now.strftime("%d/%m/%Y %H:%M:%S")
print("Starting the fit: date and time = ", dt_string)
tbl = phot(data_array, init_guesses=init_tbl)
now = datetime.now()
dt_string = now.strftime("%d/%m/%Y %H:%M:%S")
print("Ending the fit: date and time = ", dt_string)
# Now I format the output
tbl['x_fit'].format = '%.1f'
tbl['y_fit'].format = '%.1f'
tbl['flux_fit'].format = '%.4e'
tbl['flux_unc'].format = '%.4e'
tbl['x_0_unc'].format = '%.4e'
tbl['y_0_unc'].format = '%.4e'
diff = phot.get_residual_image()
hdu_out = fits.PrimaryHDU(diff, header=fheader)
hdul_out = fits.HDUList([hdu_out])
hdul_out.writeto(data_file + '_residual.fits')
# And create a residual image from the fit
plt.figure(figsize=(9, 9))
imshow_norm(diff, interval=PercentileInterval(99.), stretch=SqrtStretch())
#plt.scatter(tbl['x_fit'], tbl['y_fit'], s=80, facecolors='none', edgecolors='r')
plt.colorbar()
plt.savefig(data_file + '_residual.png', dpi=300)
plt.clf()
# Calculate the RA and DEC values from the x_fit and y_fit values.
RA_fit = np.zeros(len(tbl['x_fit']))
DEC_fit = np.zeros(len(tbl['x_fit']))
RA_fit, DEC_fit = imagemodel.meta.wcs(tbl['x_fit'], tbl['y_fit'])
tbl.add_column(DEC_fit, index=0, name='DEC_fit')
tbl.add_column(RA_fit, index=0, name='RA_fit')
# And write out the table to a file.
tbl.write(data_file + '_psf_fit_output.fits')
def img_measure_background(img, use_sep=True, **kwargs):
"""Estimate sky background of an image.
For SEP, available parameters are:
sep_kwargs = {'mask': None,
'bw': 20, 'bh': 20, 'fw': 3, 'fh':3, }
For Photutils, available parameters are:
phot_kwargs = {'bkg': 'median', 'rms': 'mad', 'mask': None,
'clip': True, 'sigma': 3.0, 'iters': 10,
'bw': 20, 'bh': 20, 'fw': 3, 'fh':3, }
"""
if use_sep:
# Use SEP for background
sep_back = sep.Background(img, **kwargs)
return sep_back.back(), sep_back.rms()
else:
# Use the photutils.background instead
if _check_kwargs(kwargs, 'clip', True):
sigma_clip = SigmaClip(sigma=_check_kwargs(kwargs, 'sigma', 3.0),
iters=_check_kwargs(kwargs, 'iters', 3))
else:
sigma_clip = None
bkg = _check_kwargs(kwargs, 'bkg', 'sextractor')
rms = _check_kwargs(kwargs, 'rms', 'biweight')
if bkg == 'biweight':
from photutils import BiweightLocationBackground
bkg_estimator = BiweightLocationBackground()
elif bkg == 'sextractor':
from photutils import SExtractorBackground
bkg_estimator = SExtractorBackground()
elif bkg == 'mmm':
from photutils import MMMBackground
bkg_estimator = MMMBackground()
elif bkg == 'median':
from photutils import MedianBackground
bkg_estimator = MedianBackground()
else:
raise Exception("# Wrong choice of background estimator!")
if rms == 'biweight':
from photutils import BiweightScaleBackgroundRMS
rms_estimator = BiweightScaleBackgroundRMS()
elif rms == 'mad':
from photutils import MADStdBackgroundRMS
rms_estimator = MADStdBackgroundRMS()
elif rms == 'std':
from photutils import StdBackgroundRMS
rms_estimator = StdBackgroundRMS()
else:
raise Exception("# Wrong choice of RMS estimator!")
bw = kwargs['bw'] if ('bw' in kwargs) else 3
bh = kwargs['bh'] if ('bh' in kwargs) else 3
fw = kwargs['fw'] if ('fw' in kwargs) else 3
fh = kwargs['fh'] if ('fh' in kwargs) else 3
bkg = Background2D(img, (_check_kwargs(
kwargs, 'bh', 100), _check_kwargs(kwargs, 'bw', 100)),
filter_size=(_check_kwargs(kwargs, 'fh', 3),
_check_kwargs(kwargs, 'fw', 3)),
mask=_check_kwargs(kwargs, 'mask', None),
sigma_clip=sigma_clip,
bkg_estimator=bkg_estimator,
bkgrms_estimator=rms_estimator)
return bkg.background, bkg.background_rms
fwhm = sigma_psf * gaussian_sigma_to_fwhm #sigma=fwhm/gaussian_sigma_to_fwhm # sigma=fwhm/(2.0*np.sqrt(2.0*np.log10(2.0)))???? # group_maker from photutils.psf import DAOGroup daogroup = DAOGroup(2.0 * fwhm) fitsfile = '3C345-20190714@135841-R_Astrodon_2018_calib.fits' hdu = fits.open(fitsfile) imhead = hdu[0].header imdata = hdu[0].data # bkg_estimator from photutils import MMMBackground bkg_estimator = MMMBackground() from photutils.background import MADStdBackgroundRMS bkgrms = MADStdBackgroundRMS() std = bkgrms(imdata) # error threshold = 3.5 * std # background level and error from astropy.stats import sigma_clipped_stats mean, median, std = sigma_clipped_stats(imdata, sigma=3.) # print(mean,median,std) # 1176.6646745343921 1176.0827349796416 39.1334108277639 # fitter from astropy.modeling.fitting import LevMarLSQFitter fitter = LevMarLSQFitter()