def norm_dist(src1, src2):
"""
Calculate the normalised distance between two sources.
Sources are elliptical Gaussians.
The normalised distance is calculated as the GCD distance between the centers,
divided by quadrature sum of the radius of each ellipse along a line joining the two ellipses.
For ellipses that touch at a single point, the normalized distance will be 1/sqrt(2).
Parameters
----------
src1, src2 : object
The two positions to compare. Objects must have the following parameters: (ra, dec, a, b, pa).
Returns
-------
dist: float
The normalised distance.
"""
if src1 == src2:
return 0
dist = gcd(src1.ra, src1.dec, src2.ra, src2.dec) # degrees
# the angle between the ellipse centers
phi = bear(src1.ra, src1.dec, src2.ra, src2.dec) # Degrees
# Calculate the radius of each ellipse along a line that joins their centers.
r1 = src1.a * src1.b / np.hypot(src1.a * np.sin(np.radians(phi - src1.pa)),
src1.b * np.cos(np.radians(phi - src1.pa)))
r2 = src2.a * src2.b / np.hypot(
src2.a * np.sin(np.radians(180 + phi - src2.pa)),
src2.b * np.cos(np.radians(180 + phi - src2.pa)))
R = dist / (np.hypot(r1, r2) / 3600)
return R
def pix2sky_vec(self, pixel, r, theta):
"""
Convert a vector from pixel to sky coords
vector is calculated at an origin pixel=(x,y)
and has a magnitude (r) [in pixels]
and an angle (theta) [in degrees]
input:
pixel - (x,y) of origin
r - magnitude in pixels
theta - in degrees
return:
ra,dec - corresponding to pixels x,y
r,pa - magnitude and angle (degrees) of the original vector, as measured on the sky
"""
ra1, dec1 = self.pix2sky(pixel)
x, y = pixel
a = [
x + r * np.cos(np.radians(theta)),
y + r * np.sin(np.radians(theta))
]
locations = self.pix2sky(a)
ra2, dec2 = locations
a = gcd(ra1, dec1, ra2, dec2)
pa = bear(ra1, dec1, ra2, dec2)
return ra1, dec1, a, pa
def pix2sky_ellipse(self, pixel, sx, sy, theta):
"""
Convert an ellipse from pixel to sky coords
sx/sy vectors are calculated at an origin pos=(x,y)
Input parameters are:
x,y - the x,y pixels corresponding to the ra/dec position
sx, sy - the major minor axes (FWHM) in pixels
theta - the position angle in degrees
Output params are all in degrees
:param pixel: [x,y] of the ellipse center
:param sx: major axis
:param sy: minor axis
:param theta: position angle
:return: ra, dec, a, b, pa
"""
ra, dec = self.pix2sky(pixel)
x, y = pixel
v_sx = [
x + sx * np.cos(np.radians(theta)),
y + sx * np.sin(np.radians(theta))
]
ra2, dec2 = self.pix2sky(v_sx)
major = gcd(ra, dec, ra2, dec2)
pa = bear(ra, dec, ra2, dec2)
v_sy = [
x + sy * np.cos(np.radians(theta - 90)),
y + sy * np.sin(np.radians(theta - 90))
]
ra2, dec2 = self.pix2sky(v_sy)
minor = gcd(ra, dec, ra2, dec2)
pa2 = bear(ra, dec, ra2, dec2) - 90
# The a/b vectors are perpendicular in sky space, but not always in pixel space
# so we have to account for this by calculating the angle between the two vectors
# and modifying the minor axis length
defect = pa - pa2
minor *= abs(np.cos(np.radians(defect)))
return ra, dec, major, minor, pa
def pix2sky_ellipse(self, pixel, sx, sy, theta):
"""
Convert an ellipse from pixel to sky coords
sx/sy vectors are calculated at an origin pos=(x,y)
Input parameters are:
x,y - the x,y pixels corresponding to the ra/dec position
sx, sy - the major minor axes (FWHM) in pixels
theta - the position angle in degrees
Output params are all in degrees
:param pixel: [x,y] of the ellipse center
:param sx: major axis
:param sy: minor axis
:param theta: position angle
:return: ra, dec, a, b, pa
"""
ra, dec = self.pix2sky(pixel)
x, y = pixel
v_sx = [x + sx * np.cos(np.radians(theta)),
y + sx * np.sin(np.radians(theta))]
ra2, dec2 = self.pix2sky(v_sx)
major = gcd(ra, dec, ra2, dec2)
pa = bear(ra, dec, ra2, dec2)
v_sy = [x + sy * np.cos(np.radians(theta-90)),
y + sy * np.sin(np.radians(theta-90))]
ra2, dec2 = self.pix2sky(v_sy)
minor = gcd(ra, dec, ra2, dec2)
pa2 = bear(ra, dec, ra2, dec2) - 90
# The a/b vectors are perpendicular in sky space, but not always in pixel space
# so we have to account for this by calculating the angle between the two vectors
# and modifying the minor axis length
defect = pa - pa2
minor *= abs(np.cos(np.radians(defect)))
return ra, dec, major, minor, pa
def norm_dist(src1,src2):
"""
Calculate the normalised distance between two sources.
Sources are elliptical gaussians.
:param src1:
:param src2:
:return:
"""
if src1 == src2:
return 0
dist = gcd(src1.ra, src1.dec, src2.ra, src2.dec) # degrees
# the angle between the ellipse centers
phi = bear(src1.ra, src1.dec, src2.ra, src2.dec) # Degrees
# Calculate the radius of each ellpise along a line that joins their centers.
r1 = src1.a*src1.b / np.hypot(src1.a * np.sin(np.radians(phi - src1.pa)),
src1.b * np.cos(np.radians(phi - src1.pa)))
r2 = src2.a*src2.b / np.hypot(src2.a * np.sin(np.radians(180 + phi - src2.pa)),
src2.b * np.cos(np.radians(180 + phi - src2.pa)))
R = dist / (np.hypot(r1,r2) / 3600)
return R
def norm_dist(src1, src2):
"""
Calculate the normalised distance between two sources.
Sources are elliptical gaussians.
:param src1:
:param src2:
:return:
"""
if src1 == src2:
return 0
dist = gcd(src1.ra, src1.dec, src2.ra, src2.dec) # degrees
# the angle between the ellipse centers
phi = bear(src1.ra, src1.dec, src2.ra, src2.dec) # Degrees
# Calculate the radius of each ellpise along a line that joins their centers.
r1 = src1.a * src1.b / np.hypot(src1.a * np.sin(np.radians(phi - src1.pa)),
src1.b * np.cos(np.radians(phi - src1.pa)))
r2 = src2.a * src2.b / np.hypot(
src2.a * np.sin(np.radians(180 + phi - src2.pa)),
src2.b * np.cos(np.radians(180 + phi - src2.pa)))
R = dist / (np.hypot(r1, r2) / 3600)
return R
def pix2sky_vec(self, pixel, r, theta):
"""
Convert a vector from pixel to sky coords
vector is calculated at an origin pixel=(x,y)
and has a magnitude (r) [in pixels]
and an angle (theta) [in degrees]
input:
pixel - (x,y) of origin
r - magnitude in pixels
theta - in degrees
return:
ra,dec - corresponding to pixels x,y
r,pa - magnitude and angle (degrees) of the original vector, as measured on the sky
"""
ra1, dec1 = self.pix2sky(pixel)
x, y = pixel
a = [x + r * np.cos(np.radians(theta)),
y + r * np.sin(np.radians(theta))]
locations = self.pix2sky(a)
ra2, dec2 = locations
a = gcd(ra1, dec1, ra2, dec2)
pa = bear(ra1, dec1, ra2, dec2)
return ra1, dec1, a, pa
def errors(source, model, wcshelper):
"""
Convert pixel based errors into sky coord errors
:param source: Source object
:param wcshelper: WCSHelper object
:return:
"""
# if the source wasn't fit then all errors are -1
if source.flags & (flags.NOTFIT | flags.FITERR):
source.err_peak_flux = source.err_a = source.err_b = source.err_pa = -1
source.err_ra = source.err_dec = source.err_int_flux = -1
return source
# copy the errors from the model
prefix = "c{0}_".format(source.source)
err_amp = model[prefix+'amp'].stderr
xo,yo = model[prefix+'xo'].value, model[prefix+'yo'].value
err_xo = model[prefix+'xo'].stderr
err_yo = model[prefix+'yo'].stderr
sx, sy = model[prefix+'sx'].value, model[prefix+'sy'].value
err_sx = model[prefix+'sx'].stderr
err_sy = model[prefix+'sy'].stderr
theta = model[prefix+'theta'].value
err_theta = model[prefix+'theta'].stderr
source.err_peak_flux = err_amp
pix_errs = [err_xo,err_yo,err_sx,err_sy,err_theta]
# check for inf/nan errors -> these sources have poor fits.
if not all([ a is not None and np.isfinite(a) for a in pix_errs]):
source.flags |= flags.FITERR
source.err_peak_flux = source.err_a = source.err_b = source.err_pa = -1
source.err_ra = source.err_dec = source.err_int_flux = -1
return source
# position errors
if model[prefix + 'xo'].vary and model[prefix + 'yo'].vary:
ref = wcshelper.pix2sky([xo,yo])
offset = wcshelper.pix2sky([xo+err_xo,yo+err_yo])
source.err_ra = gcd(ref[0], ref[1], offset[0], ref[1])
source.err_dec = gcd(ref[0], ref[1], ref[0], offset[1])
else:
source.err_ra = source.err_dec = -1
if model[prefix + 'sx'].vary and model[prefix + 'sy'].vary:
# major axis error
ref = wcshelper.pix2sky([xo+sx*np.cos(np.radians(theta)),yo+sy*np.sin(np.radians(theta))])
offset = wcshelper.pix2sky([xo+(sx+err_sx)*np.cos(np.radians(theta)),yo+sy*np.sin(np.radians(theta))])
source.err_a = gcd(ref[0],ref[1],offset[0],offset[1]) * 3600
# minor axis error
ref = wcshelper.pix2sky([xo+sx*np.cos(np.radians(theta+90)),yo+sy*np.sin(np.radians(theta+90))])
offset = wcshelper.pix2sky([xo+sx*np.cos(np.radians(theta+90)),yo+(sy+err_sy)*np.sin(np.radians(theta+90))])
source.err_b = gcd(ref[0], ref[1], offset[0], offset[1]) * 3600
else:
source.err_a = source.err_b = -1
if model[prefix+'theta'].vary:
# pa error
ref = wcshelper.pix2sky([xo,yo])
off1 = wcshelper.pix2sky([xo+sx*np.cos(np.radians(theta)),yo+sy*np.sin(np.radians(theta))])
off2 = wcshelper.pix2sky([xo+sx*np.cos(np.radians(theta+err_theta)),yo+sy*np.sin(np.radians(theta+err_theta))])
source.err_pa = abs(bear(ref[0], ref[1], off1[0], off1[1]) - bear(ref[0], ref[1], off2[0], off2[1]))
else:
source.err_pa = -1
sqerr = 0
sqerr += (source.err_peak_flux/source.peak_flux)**2 if source.err_peak_flux >0 else 0
sqerr += (source.err_a/source.a)**2 if source.err_a > 0 else 0
sqerr += (source.err_b/source.b)**2 if source.err_b > 0 else 0
source.err_int_flux = source.int_flux*np.sqrt(sqerr)
# logging.info("src ({0},{1})".format(source.island,source.source))
# logging.info(" pixel errs {0}".format([err_xo, err_yo, err_sx, err_sy, err_theta]))
# logging.info(" sky errs {0}".format([source.err_ra, source.err_dec, source.err_a, source.err_b, source.err_pa]))
return source
def errors(source, model, wcshelper):
"""
Convert pixel based errors into sky coord errors
:param source: Source object
:param wcshelper: WCSHelper object
:return:
"""
# if the source wasn't fit then all errors are -1
if source.flags & (flags.NOTFIT | flags.FITERR):
source.err_peak_flux = source.err_a = source.err_b = source.err_pa = -1
source.err_ra = source.err_dec = source.err_int_flux = -1
return source
# copy the errors from the model
prefix = "c{0}_".format(source.source)
err_amp = model[prefix + 'amp'].stderr
xo, yo = model[prefix + 'xo'].value, model[prefix + 'yo'].value
err_xo = model[prefix + 'xo'].stderr
err_yo = model[prefix + 'yo'].stderr
sx, sy = model[prefix + 'sx'].value, model[prefix + 'sy'].value
err_sx = model[prefix + 'sx'].stderr
err_sy = model[prefix + 'sy'].stderr
theta = model[prefix + 'theta'].value
err_theta = model[prefix + 'theta'].stderr
source.err_peak_flux = err_amp
pix_errs = [err_xo, err_yo, err_sx, err_sy, err_theta]
# check for inf/nan errors -> these sources have poor fits.
if not all([a is not None and np.isfinite(a) for a in pix_errs]):
source.flags |= flags.FITERR
source.err_peak_flux = source.err_a = source.err_b = source.err_pa = -1
source.err_ra = source.err_dec = source.err_int_flux = -1
return source
# position errors
if model[prefix + 'xo'].vary and model[prefix + 'yo'].vary:
ref = wcshelper.pix2sky([xo, yo])
offset = wcshelper.pix2sky([xo + err_xo, yo + err_yo])
source.err_ra = gcd(ref[0], ref[1], offset[0], ref[1])
source.err_dec = gcd(ref[0], ref[1], ref[0], offset[1])
else:
source.err_ra = source.err_dec = -1
if model[prefix + 'sx'].vary and model[prefix + 'sy'].vary:
# major axis error
ref = wcshelper.pix2sky([
xo + sx * np.cos(np.radians(theta)),
yo + sy * np.sin(np.radians(theta))
])
offset = wcshelper.pix2sky([
xo + (sx + err_sx) * np.cos(np.radians(theta)),
yo + sy * np.sin(np.radians(theta))
])
source.err_a = gcd(ref[0], ref[1], offset[0], offset[1]) * 3600
# minor axis error
ref = wcshelper.pix2sky([
xo + sx * np.cos(np.radians(theta + 90)),
yo + sy * np.sin(np.radians(theta + 90))
])
offset = wcshelper.pix2sky([
xo + sx * np.cos(np.radians(theta + 90)),
yo + (sy + err_sy) * np.sin(np.radians(theta + 90))
])
source.err_b = gcd(ref[0], ref[1], offset[0], offset[1]) * 3600
else:
source.err_a = source.err_b = -1
if model[prefix + 'theta'].vary:
# pa error
ref = wcshelper.pix2sky([xo, yo])
off1 = wcshelper.pix2sky([
xo + sx * np.cos(np.radians(theta)),
yo + sy * np.sin(np.radians(theta))
])
off2 = wcshelper.pix2sky([
xo + sx * np.cos(np.radians(theta + err_theta)),
yo + sy * np.sin(np.radians(theta + err_theta))
])
source.err_pa = abs(
bear(ref[0], ref[1], off1[0], off1[1]) -
bear(ref[0], ref[1], off2[0], off2[1]))
else:
source.err_pa = -1
sqerr = 0
sqerr += (source.err_peak_flux /
source.peak_flux)**2 if source.err_peak_flux > 0 else 0
sqerr += (source.err_a / source.a)**2 if source.err_a > 0 else 0
sqerr += (source.err_b / source.b)**2 if source.err_b > 0 else 0
source.err_int_flux = source.int_flux * np.sqrt(sqerr)
# logging.info("src ({0},{1})".format(source.island,source.source))
# logging.info(" pixel errs {0}".format([err_xo, err_yo, err_sx, err_sy, err_theta]))
# logging.info(" sky errs {0}".format([source.err_ra, source.err_dec, source.err_a, source.err_b, source.err_pa]))
return source