Displaced positions give a closer W1 flux match than Gaia positions for six white dwarfs in 2010–2020 images

We test whether the position offsets in six released white dwarf light curves affect the measured flux. An earlier SCI audit found the offsets but did not measure image flux. We test all six unflagged variables with an offset greater than the 5.5 arcsecond aperture radius in that audit. We use 114 public neo7 unWISE W1 coadds from 2010–2020. We measure each image at the released position track and at the Gaia DR3 track with the same aperture and sky rule. The sample was fixed before inspection of image flux. There are 95 valid matched epochs. In all 95, the displaced-position flux is closer to the released flux than the Gaia-position flux. This holds for both median and mean sky subtraction. With median sky subtraction, the ratio of median displaced-position flux to median released flux is 0.973–1.038 across sources. At the Gaia position, the ratio is 2.146–35.426. We compute the root mean square (RMS) flux difference from the release. The RMS at the Gaia position is 47.7–302.1 times the RMS at the displaced position. With mean sky subtraction, this ratio is 4.19–125.91. The absolute flux scale depends on the sky estimate. These image measurements support a measurement-position error in the six released W1 series. They do not determine whether the stars have intrinsic brightness changes. The original study uses a later image release; this test covers only matched W1 epochs for six sources. The package contains image cutouts, original released tables, source code, provenance, figures, and instructions for an offline repeat and a network rebuild.

white dwarfs · unWISE · WISE W1 · proper motion · aperture photometry · position errors · data validation · reproducible measurements