DS9 Guide

DS9 is an astronomical imaging program that is compatible with IRAF.

The official DS9 Reference Manual is very helpful and easy to use. This tutorial will only provide basic information about the most useful options.

Startup

To run DS9 from the UNIX command window, enter:

ds9 filename&

You do not need to indicate a filename. If you do enter a filename, DS9 will open with that image loaded. If not, DS9 will open with a blank frame.

The area directly under the top menu bar provides information about the file, the pixel count at the cursor's location, the XY-coordinate location of the cursor, and the current magnification.

The Basics

Once your image is displayed, you can use DS9 to analyze it. The tabs above the image contain most of the commands you will need.

The File tab allows you to open images, save altered images, and view the image header. The image header presented in DS9 does not contain much useful information, so it is better to rely on IRAF for information about the image.

The Edit tab lets you copy, cut, and paste bits of the image. Other options let you examine a small section of the image or rotate the frame.

The Frame tab contains lots of useful options for manipulating several images at once.

new opens a new blank frame.
clear clears the contents of a frame, but does not delete the actual file.
delete both clears the frame and deletes the source file.
tile shows all frames at once
single When the tile option is on, you can click on one image and it will be outlined in blue. The single option will then display only the selected image.
blink flashes all frames on the screen for comparison
First, Prev, Next, and Last allow you to scroll through the frames

You can display up to 4 frames in DS9.

The Zoom tab allows you to change the view. To adjust the image size so that you can see all of it, select Zoom from the upper menu bar and then Zoom to Fit Frame. If you want the cursor to move in integer amounts, select Zoom from the menu bar and 1. Now you will only see whole numbers for the cursor's coordinates.

The Scale tab is unavailable when you open an image through IRAF. If the Scale tab is available, you can experiment with adjusting the appearance of your image.

Holding down the right mouse button and dragging the mouse in the Y-direction adjusts the contrast. Dragging in the X-direction adjusts the brightness. This is useful when the Scale tab is unavailable.

The Color tab is used to colorize images in various ways. The most useful choices are the red, green, and blue colorizations, since they correspond to filter colors and could be used to colorize your images.

The Region tab can be used to alter the appearance of the markers that appear when you click on the image.

Using DS9 with IRAF

Start by typing "ds9 &" from the UNIX command window. To view an image, type "display imagename" in the IRAF command window. IRAF will also prompt you for a frame number between 1 and 4.

If you have created a .map or .reg file in IRAF and want to see the locations of the stars found by daofind, first make sure that the corresponding .fit file is loaded. Then click on Region in the top menu bar, select File Format, and change it to XY. You can then load the .map or .reg file by clicking again on Region and choosing Load Regions. Locate your file and click "OK". The stars IRAF found using daofind will be shown in green markers.