The Visual Target Tuner

The Visual Target Tuner (VTT) tool in APT allows you to select an exposure specification in the hierarchical editor and have the specified aperture displayed as an overlay on an image (Digitized Sky Survey or with another standard FITS image file that you provide). The image viewer has some standard features such as pan, zoom, and gray scale control. You can display the HST FOV, catalog overlays (such as the Guide Star Catalog), and move targets and apertures in the display.

A Quick Start

These directions provide quick instructions for beginning a standard VTT session.

First, see the README FIRST in this help document before proceeding.
In the hierarchical editor select an exposure specification and then click on the VTT tool icon.
The Image Chooser dialog will display with the RA and DEC of the target for the selected exposure already filled in. You may load an image from one of the available image databases or load a FITS image from a local file. A progress bar will display as the image is loaded.
Once loaded, the aperture for the selected exposure will be displayed as an overlay on the image. Depending on the options selected in the VTT, a target indicator, coordinate grid, or catalog overlay may also appear.

A Quick Tour of the Display

After selecting an exposure, retrieving an image and turning on some of the VTT display options, the VTT should look about like this. See below for a desciption of the labeled items in the figure.

A. The current selection in the hierarchical editor
B. The menu bar
C. The top tool bar
D. The side tool bar
E. Names of catalog entries
F. The outline of the selected aperture. To rotate the observation, click and drag one of the aperture's four corners.
G. The parallel exposure
H. The current targeted position, represented as J2000 Right Ascension and Declination. You can change the position by displaying the target crosshair and then selecting and dragging the target.
I. Button to access the Orientation Detail window.
J. Status indicators showing the current aperture orientation, pixel location, pixel data value, and coordinates of the cursor
K. Inscribed and circumscribed circles which represent areas that will always be imaged or may be imaged depending on orientation
L. The fiducial point of the selected aperture, represented by a small cross hair icon. You can change the position by clicking on this icon and dragging it across the image.