This document shows how to review and update patterns using Aladin (click here to see the movie). The project is to mosaic the galaxy M51 using the WFC3/UVIS camera. In Phase I, we determined that a 4-step box pattern, with an ORIENT of 130-135 degrees would cover the galaxy. The original coordinates came from a catalog, and were not closely verified in Phase I

We have already loaded in DSS image into Aladin. With Exposure 1 selected in the APT Tree Editor, we see that our Orientation is good, but that the pattern is not centered on the galaxy.

We grab the aperture and move it to center the middle tile on the galaxy. Note that all pieces of the pattern move in conjunction with the single aperture we adjust. Going back to the APT window, we see that our coordinate change is listed as a pending change, which we now commit to the proposal.

However, we noted that the overlap between the WFC3/IR positions is too small. We switch back to the Form Editor and select the box pattern to review the parameters. Our line spacing of 77.5" is too large, so we change it to 65".

Going back to the Aladin window, we now see that the overlap is sufficient, and the galaxy coverage is good enough that we do not need to add an additional tile.

Last modified: June 2, 2016.