spatial matching error seen in sub-milliarcsecond scale images

[kswang1029]

reported by a user

To study this issue and exclude potential proper motion in different epochs, I made three test images with different reference centers. The gaussian sources are 0.0001arcsec each in size. The pixel sizes are 0.00002arcsec, 0.000023arcsec, and 0.000019arcsec, respectively. So we can use this set of images to test spatial matching at such scales. These images before matching look like the following

I tried to set the reference image to one of the images and match the others. The results are summarized below where v means matching correctly, and x means incorrectly.

We see Gaussian2.fits has the issue (demo with Gaussan1.fits as the reference image).

While using Gaussian3.fits as the reference, all the other two images can be matched well.

I suspect this might be a coordinate rounding issue as we can see the offset is ~ the separation of the two close Gaussians.

Test image attached.

tmp.zip

[kswang1029]

@veggiesaurus help wanted~

[kswang1029]

assignee @veggiesaurus or @YuHsuan-Hwang TBD