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Restrict "tweaked moments" for "free shape" #187

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Merged
HannoSpreeuw merged 1 commit into from
Dec 16, 2025
Merged

Restrict "tweaked moments" for "free shape" #187

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21 changes: 9 additions & 12 deletions sourcefinder/measure.py
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Original file line number Diff line number Diff line change
Expand Up @@ -369,8 +369,9 @@ def moments_enhanced(
island. Units: pixels.

maxi : float
Peak pixel value within the island. Units: spectral brightness,
typically Jy/beam. To clarify: source_island[maxpos] == maxi.
Peak pixel value within the island. Pixel values represent spectral
brightness (typically in Jy/beam).
For clarity: source_island[maxpos] == maxi.

fudge_max_pix_factor : float
Correction factor for underestimation of the peak by considering the
Expand Down Expand Up @@ -464,6 +465,8 @@ def moments_enhanced(
# dump the redundant elements that have undetermined values.
source_island = source_island[:no_pixels]
noise_island = noise_island[:no_pixels]
posx = posx[:no_pixels]
posy = posy[:no_pixels]
# The significance of a source detection is determined in this way.
significance[0] = (source_island / noise_island).max()

Expand Down Expand Up @@ -504,13 +507,7 @@ def moments_enhanced(
i = np.nonzero(mask)[0][0]
basepos = rounded_barycenter
basevalue = source_island[i]
else:
# The rounded barycenter position is not in source_island, so we
# revert to the maximum pixel position, which is always included.
basepos = maxpos[0] - chunkpos[0], maxpos[1] - chunkpos[1]
basevalue = maxi

deltax, deltay = xbar - basepos[0], ybar - basepos[1]
deltax, deltay = xbar - basepos[0], ybar - basepos[1]

if force_beam:
# If the restoring beam is forced, we use the beam parameters
Expand Down Expand Up @@ -595,7 +592,7 @@ def moments_enhanced(
else:
theta -= math.pi / 2.0

if np.sign(threshold) == np.sign(basevalue):
if np.sign(threshold) == np.sign(basevalue) and in_source_island:
# Implementation of "tweaked moments", equation 2.67 from
# Spreeuw's thesis. In that formula the "base position" was the
# maximum pixel position. Here that is the rounded
Expand All @@ -620,9 +617,9 @@ def moments_enhanced(
# Gaussian fits.
if basevalue > 0:
low_bound = 0.5 * basevalue
upp_bound = 1.5 * basevalue
upp_bound = 2.0 * basevalue
else:
low_bound = 1.5 * basevalue
low_bound = 2.0 * basevalue
upp_bound = 0.5 * basevalue

# The number of iterations used for the root finder is also
Expand Down