Changing the Target Position

There are three ways to change the target position. First select the target you want to change in the APT target list. (If an exposure is selected then changes to the exposure position will result in a PosTarg offset being created for the exposure.)

Dragging

First ensure that you are in the Select Mode (

in the left hand tool bar). Now align your cursor with the targeted position icon (which is a small cross hair). The cursor will change into a pointing hand. When the pointing hand is visible, click and drag with the left mouse button. The target coordinates are displayed in the bottom left hand corner of the image viewer and will update as the target position changes. Releasing the mouse button completes the move. This action does not update the target RA and DEC in the proposal until you click the "SAVE" button in the top tool bar.

Editing the Target Coordinates

You can update the desired target coordinates using the RA and Dec fields in the mini-spreadsheet when the target has been selected in the APT target list. Click in the boxes and change the coordinates.

Note that if the position you select is not on the image, the target position icon will not be visible on your image.

Centroiding

Using the centroid tool (

in the left hand tool bar) will not only compute the centroid of the area, it will also change the target position to the calculated center. This action does not update the target RA and DEC in the proposal until you click the "SAVE" button in the top tool bar.