We have already loaded in the 3 HST images, as well as the
DSS image, into Aladin.
The Multiview 4-panel mode has been selected to display all
4 images in the Aladin display. Note that the aperture is centered
on the measured star, and that Exposure 1 is selected.
In the APT window, select the Create POS TARG mode option. In the Aladin window, drag and place the aperture on the first filament of interest. Note the line drawn from the star to the filament, indicating a POS TARG has been created, and that the POS TARG appears on all 4 images.
Select exposures 2 and 3 and places the apertures on the remaining 2 filaments. In the APT window, you will see the POS TARGs in the pending changes area.
You could select all the changes individually, select the Visit, or select the Commit All option to save the changes to the proposal; similarly, if you did not like the changes, you could clear them as well.
With the Visit container selected
in the APT Tree Editor, go back to the Aladin window to review