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DM-53369: Add post-subtracted background stats to calibrateImage metadata metrics #1196

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Nov 27, 2025
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DM-53369: Add post-subtracted background stats to calibrateImage metadata metrics #1196

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35 changes: 35 additions & 0 deletions python/lsst/pipe/tasks/calibrateImage.py
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Original file line number Diff line number Diff line change
Expand Up @@ -451,6 +451,14 @@ class CalibrateImageConfig(pipeBase.PipelineTaskConfig, pipelineConnections=Cali
doc="If True, include astrometric errors in the output catalog.",
)

background_stats_ignored_pixel_masks = pexConfig.ListField(
dtype=str,
default=["SAT", "SUSPECT", "SPIKE"],
doc="Pixel mask flags to ignore when calculating post-sky-subtraction "
"background statistics. These are added to those ignored by the "
"meas.algorithms.SubtractBackgroundConfig algorithm."
)

run_sattle = pexConfig.Field(
dtype=bool,
default=False,
Expand Down Expand Up @@ -1092,6 +1100,33 @@ def run(
else:
self._summarize(result.exposure, summary_stat_catalog, result.background)

# Output post-subtraction background stats to task metadata:
# Specify the pixels flags to ignore, starting with those ignored
# by the subtraction.
bgIgnoredPixelMasks = lsst.meas.algorithms.SubtractBackgroundConfig().ignoredPixelMask.list()
for maskName in self.config.background_stats_ignored_pixel_masks:
if (maskName in result.exposure.mask.getMaskPlaneDict().keys()
and maskName not in bgIgnoredPixelMasks):
bgIgnoredPixelMasks += [maskName]

statsCtrl = afwMath.StatisticsControl()
statsCtrl.setAndMask(afwImage.Mask.getPlaneBitMask(bgIgnoredPixelMasks))

statObj = afwMath.makeStatistics(result.exposure.getMaskedImage(), afwMath.MEDIAN, statsCtrl)
median_bg, _ = statObj.getResult(afwMath.MEDIAN)
self.metadata["bg_subtracted_skyPixel_instFlux_median"] = median_bg

statObj = afwMath.makeStatistics(result.exposure.getMaskedImage(), afwMath.STDEV, statsCtrl)
stdev_bg, _ = statObj.getResult(afwMath.STDEV)
self.metadata["bg_subtracted_skyPixel_instFlux_stdev"] = stdev_bg

self.metadata["bg_subtracted_skySource_flux_median"] = (
np.median(result.stars[result.stars['sky_source']]['base_CircularApertureFlux_12_0_flux'])
)
self.metadata["bg_subtracted_skySource_flux_stdev"] = (
np.std(result.stars[result.stars['sky_source']]['base_CircularApertureFlux_12_0_flux'])
)

if self.config.do_calibrate_pixels:
self._apply_photometry(
result.exposure,
Expand Down