def extract_ifu(input_model, source_type, extract_params):
"""This function does the extraction.
Parameters
----------
input_model : IFUCubeModel
The input model.
source_type : string
"POINT" or "EXTENDED"
extract_params : dict
The extraction parameters for aperture photometry.
Returns
-------
ra, dec : float
ra and dec are the right ascension and declination respectively
at the nominal center of the image.
wavelength : ndarray, 1-D
The wavelength in micrometers at each plane of the IFU cube.
temp_flux : ndarray, 1-D
The sum of the data values in the extraction aperture minus the
sum of the data values in the background region (scaled by the
ratio of areas), for each plane.
The data values are in units of surface brightness, so this value
isn't really the flux, it's an intermediate value. Dividing by
`npixels` (to compute the average) will give the value for the
`surf_bright` (surface brightness) column, and multiplying by
the solid angle of a pixel will give the flux for a point source.
background : ndarray, 1-D
The background count rate that was subtracted from the total
source data values to get `temp_flux`.
npixels : ndarray, 1-D, float64
For each slice, this is the number of pixels that were added
together to get `temp_flux`.
dq : ndarray, 1-D, uint32
The data quality array.
npixels_annulus : ndarray, 1-D, float64
For each slice, this is the number of pixels that were added
together to get `temp_flux` for an annulus region.
radius_match: ndarray,1-D, float64
The size of the extract radius in pixels used at each wavelength of the IFU cube
x_center, y_center : float
The x and y center of the extraction region
"""
data = input_model.data
weightmap = input_model.weightmap
shape = data.shape
if len(shape) != 3:
log.error("Expected a 3-D IFU cube; dimension is %d.", len(shape))
raise RuntimeError("The IFU cube should be 3-D.")
# We need to allocate temp_flux, background, npixels, and dq arrays
# no matter what. We may need to divide by npixels, so the default
# is 1 rather than 0.
temp_flux = np.zeros(shape[0], dtype=np.float64)
background = np.zeros(shape[0], dtype=np.float64)
npixels = np.ones(shape[0], dtype=np.float64)
npixels_annulus = np.ones(shape[0], dtype=np.float64)
dq = np.zeros(shape[0], dtype=np.uint32)
# For an extended target, the entire aperture will be extracted, so
# it makes no sense to shift the extraction location.
if source_type != "EXTENDED":
ra_targ = input_model.meta.target.ra
dec_targ = input_model.meta.target.dec
locn = locn_from_wcs(input_model, ra_targ, dec_targ)
if locn is None or np.isnan(locn[0]):
log.warning("Couldn't determine pixel location from WCS, so "
"source offset correction will not be applied.")
x_center = float(shape[-1]) / 2.
y_center = float(shape[-2]) / 2.
else:
(x_center, y_center) = locn
log.info("Using x_center = %g, y_center = %g, based on "
"TARG_RA and TARG_DEC.", x_center, y_center)
method = extract_params['method']
subpixels = extract_params['subpixels']
subtract_background = extract_params['subtract_background']
radius = None
inner_bkg = None
outer_bkg = None
width = None
height = None
theta = None
# pull wavelength plane out of input data.
# using extract 1d wavelength, interpolate the radius, inner_bkg, outer_bkg to match input wavelength
# find the wavelength array of the IFU cube
x0 = float(shape[2]) / 2.
y0 = float(shape[1]) / 2.
(ra, dec, wavelength) = get_coordinates(input_model, x0, y0)
# interpolate the extraction parameters to the wavelength of the IFU cube
radius_match = None
if source_type == 'POINT':
wave_extract = extract_params['wavelength'].flatten()
inner_bkg = extract_params['inner_bkg'].flatten()
outer_bkg = extract_params['outer_bkg'].flatten()
radius = extract_params['radius'].flatten()
frad = interp1d(wave_extract, radius, bounds_error=False, fill_value="extrapolate")
radius_match = frad(wavelength)
# radius_match is in arc seconds - need to convert to pixels
# the spatial scale is the same for all wavelengths do we only need to call compute_scale once.
if locn is None:
locn_use = (input_model.meta.wcsinfo.crval1, input_model.meta.wcsinfo.crval2, wavelength[0])
else:
locn_use = (ra_targ, dec_targ, wavelength[0])
scale_degrees = compute_scale(
input_model.meta.wcs,
locn_use,
disp_axis=input_model.meta.wcsinfo.dispersion_direction)
scale_arcsec = scale_degrees*3600.00
radius_match /= scale_arcsec
finner = interp1d(wave_extract, inner_bkg, bounds_error=False, fill_value="extrapolate")
inner_bkg_match = finner(wavelength)/scale_arcsec
fouter = interp1d(wave_extract, outer_bkg, bounds_error=False, fill_value="extrapolate")
outer_bkg_match = fouter(wavelength)/scale_arcsec
elif source_type == 'EXTENDED':
# Ignore any input parameters, and extract the whole image.
width = float(shape[-1])
height = float(shape[-2])
x_center = width / 2. - 0.5
y_center = height / 2. - 0.5
theta = 0.
subtract_background = False
log.debug("IFU 1-D extraction parameters:")
log.debug(" x_center = %s", str(x_center))
log.debug(" y_center = %s", str(y_center))
if source_type == 'POINT':
log.debug(" method = %s", method)
if method == "subpixel":
log.debug(" subpixels = %s", str(subpixels))
else:
log.debug(" width = %s", str(width))
log.debug(" height = %s", str(height))
log.debug(" theta = %s degrees", str(theta))
log.debug(" subtract_background = %s", str(subtract_background))
log.debug(" method = %s", method)
if method == "subpixel":
log.debug(" subpixels = %s", str(subpixels))
position = (x_center, y_center)
# get aperture for extended it will not change with wavelength
if source_type == 'EXTENDED':
aperture = RectangularAperture(position, width, height, theta)
annulus = None
for k in range(shape[0]):
inner_bkg = None
outer_bkg = None
if source_type == 'POINT':
radius = radius_match[k] # this radius has been converted to pixels
aperture = CircularAperture(position, r=radius)
inner_bkg = inner_bkg_match[k]
outer_bkg = outer_bkg_match[k]
if inner_bkg <= 0. or outer_bkg <= 0. or inner_bkg >= outer_bkg:
log.debug("Turning background subtraction off, due to "
"the values of inner_bkg and outer_bkg.")
subtract_background = False
if subtract_background and inner_bkg is not None and outer_bkg is not None:
annulus = CircularAnnulus(position, r_in=inner_bkg, r_out=outer_bkg)
else:
annulus = None
subtract_background_plane = subtract_background
# Compute the area of the aperture and possibly also of the annulus.
# for each wavelength bin (taking into account empty spaxels)
normalization = 1.
temp = weightmap[k,:,:]
temp[temp>1] = 1
aperture_area = 0
annulus_area = 0
# aperture_photometry - using weight map
phot_table = aperture_photometry(temp, aperture,
method=method, subpixels=subpixels)
aperture_area = float(phot_table['aperture_sum'][0])
if LooseVersion(photutils.__version__) >= '0.7':
log.debug("aperture.area = %g; aperture_area = %g",
aperture.area, aperture_area)
else:
log.debug("aperture.area() = %g; aperture_area = %g",
aperture.area(), aperture_area)
if(aperture_area ==0 and aperture.area > 0):
aperture_area = aperture.area
if subtract_background and annulus is not None:
# Compute the area of the annulus.
phot_table = aperture_photometry(temp, annulus,
method=method, subpixels=subpixels)
annulus_area = float(phot_table['aperture_sum'][0])
if LooseVersion(photutils.__version__) >= '0.7':
log.debug("annulus.area = %g; annulus_area = %g",
annulus.area, annulus_area)
else:
log.debug("annulus.area() = %g; annulus_area = %g",
annulus.area(), annulus_area)
if(annulus_area ==0 and annulus.area > 0):
annulus_area = annulus.area
if annulus_area > 0.:
normalization = aperture_area / annulus_area
else:
log.warning("Background annulus has no area, so background "
"subtraction will be turned off. %g" ,k)
subtract_background_plane = False
del temp
npixels[k] = aperture_area
npixels_annulus[k] = 0.0
if annulus is not None:
npixels_annulus[k] = annulus_area
# aperture_photometry - using data
phot_table = aperture_photometry(data[k, :, :], aperture,
method=method, subpixels=subpixels)
temp_flux[k] = float(phot_table['aperture_sum'][0])
if subtract_background_plane:
bkg_table = aperture_photometry(data[k, :, :], annulus,
method=method, subpixels=subpixels)
background[k] = float(bkg_table['aperture_sum'][0])
temp_flux[k] = temp_flux[k] - background[k] * normalization
# Check for NaNs in the wavelength array, flag them in the dq array,
# and truncate the arrays if NaNs are found at endpoints (unless the
# entire array is NaN).
(wavelength, temp_flux, background, npixels, dq, npixels_annulus) = \
nans_in_wavelength(wavelength, temp_flux, background, npixels, dq, npixels_annulus)
return (ra, dec, wavelength, temp_flux, background, npixels, dq,
npixels_annulus, radius_match, x_center, y_center)
def do_Rect_phot(pos, FWHM, trail, ap_min=3., ap_factor=1.5, \
win=None, wout=None, hout=None,\
sky_nsigma=3., sky_iter=10 ):
if win == None:
win = 4 * FWHM + trail
if wout == None:
wout = 8 * FWHM + trail
if hout == None:
hout = 8 * FWHM
N = len(pos)
if pos.ndim == 1:
N = 1
theta = give_theta(number_of_stars=5)
an = RectAn(pos, w_in=win, w_out=wout, h_out=hout, theta=theta)
ap_size = np.max([ap_min, ap_factor*FWHM])
aperture = RectAp(pos, w=(trail+ap_size), h=ap_size, theta=theta)
flux = aperture.do_photometry(image_reduc, method='exact')[0]
# do phot and get sum from aperture. [0] is sum and [1] is error.
#For test:
#FWHM = FWHM_moffat.copy()
#trail=trail_len.copy()
#win = 4 * FWHM + trail
#wout = 8 * FWHM + trail
#hout = 8 * FWHM
#N=len(pos_star_fit)
#an = RectAn(pos_star_fit, w_in=win, w_out=wout, h_out=hout, theta=(theta+np.pi/2))
#ap_size = 1.5*FWHM_moffat
#aperture = RectAp(pos_star_fit, w=(trail+ap_size), h=ap_size, theta=(theta+np.pi/2))
#flux = aperture.do_photometry(image_reduc, method='exact')[0]
#plt.figure(figsize=(12,12))
#plt.imshow(image_reduc, origin='lower', vmin=-10, vmax=1000)
#an.plot(color='white')
#aperture.plot(color='red')
flux_ss = np.zeros(N)
error = np.zeros(N)
for i in range(0, N):
mask_an = (an.to_mask(method='center'))[i]
# cf: test = mask_an.cutout(image_reduc) <-- will make cutout image.
sky_an = mask_an.apply(image_reduc)
all_sky = sky_an[np.nonzero(sky_an)]
# only annulus region will be saved as np.ndarray
msky, stdev, nsky, nrej = sky_fit(all_sky, method='Mode', mode_option='sex')
area = aperture.area()
flux_ss[i] = flux[i] - msky*area # sky subtracted flux
error[i] = np.sqrt( flux_ss[i]/gain \
+ area * stdev**2 \
+ area**2 * stdev**2 / nsky )
if inputs.star_img_save:
from matplotlib import pyplot as plt
mask_ap = (aperture.to_mask(method='exact'))[i]
star_ap_ss = mask_ap.apply(image_reduc-msky)
sky_an_ss = mask_an.apply(image_reduc-msky)
plt.suptitle('{0}, Star ID={1} ({nsky:3d} {nrej:3d} {msky:7.2f} {stdev:7.2f})'.format(
inputs.filename, i, nsky=nsky, nrej=nrej, msky=msky, stdev=stdev ))
ax1 = plt.subplot(1,2,1)
im1 = ax1.imshow(sky_an_ss, origin='lower')
plt.colorbar(im1, orientation='horizontal')
ax2 = plt.subplot(1,2,2)
im2 = ax2.imshow(star_ap_ss, origin='lower')
plt.colorbar(im2, orientation='horizontal')
plt.savefig('{0}.star{1}.png'.format(inputs.filename, i))
plt.clf()
if pos.ndim > 1:
print('\t[{x:7.2f}, {y:7.2f}], {nsky:3d} {nrej:3d} {msky:7.2f} {stdev:7.2f} {flux:7.1f} {ferr:3.1f}'.format(\
x=pos[i][0], y=pos[i][1], \
nsky=nsky, nrej=nrej, msky=msky, stdev=stdev,\
flux=flux_ss[i], ferr=error[i]))
return flux_ss, error