Planet Hunt

Using the Software

To study the Image Data files that you have downloaded, you will be using a piece of software called LTImage.

This software has been written by the National Schools' Observatory for special Image Processing of astronomical observations. With it you can display, manipulate and explore the image data.

Displaying an image

Start up the software (ask your teacher how to do this). You should see a window like the one on the right.

Click on the File menu and select Open Data Image. A new window will pop up and allow you to select one of the files that you downloaded. If you cannot find the files, ask your teacher.

Choose one of the files by clicking on it (you can choose any one, but you may find it best to start with the Moon). When you have selected a file and clicked on Open the image will be loaded in. This may take a little while as they are quite big images.

When it is loaded, the image should appear in the main part of the LTImage window.

Display Scaling

Astronomical Image Data has a lot more detail in it than the computer can display at one time. This means that if there are bright stars in the image, you may not see the object you really want to see at first.

However, LTImage lets you change the way the computer displays the image to see the fainter parts. It does this with the Display Scaling tool:

• Go to the Display menu and select Scaling.
• You should have a new Tool like the one in the picture on the right.
• In the Tool window, move the right-hand slider (labelled "Maximum") down nearly to the bottom.
• Watch the small image as you do this. When you see something interesting, click on the Use New Values button.
• Keep experimenting until you have found a picture that you like.

Zooming

In order to see the full detail of the image, you will need to Zoom in. Use the Display menu and select Zoom + (see the image on the right).

Experiment with the different Display menu options and use the scroll bars to move the image around.

Do you understand what the different options do? Can you zoom in and scroll around to find a particular part of the image? When you are happy you can do this, you are ready to look at False Colours

False Colours

Images from telescopes are usually black-and-white, so this is how the software displays them. However, our eyes are sometimes better at seeing things if we use different colours - and it can be more interesting!

Because the computer does what it is told, we can get the software to use any colours that we want. These are called False Colour Schemes.

Click on the Colour menu and choose Colour Select. The box on the right-hand side of the LTImage window will change to show a list of False Colour Schemes. Click on each Scheme in turn and see what they do.

Which colour scheme do you like most? Which lets you see the most on the image? Of course, there are only a small number of colour schemes here, and you can do better, can't you?

Go back to the Colour menu, but this time select Colour Tool. This will change the box on the right again and give you lots of buttons and sliders. You can use these to create your own false colour schemes!

Try moving some of the sliders and then click on Use new Colours. Did the colours change a lot?

Spend some time experimenting with all the buttons and sliders. Do not worry if you do not quite understand what each one does - just try them and see!

Magnifying Glass and Coordinates

Sometime, when you think that you have found something interesting, it is useful to be able to measure its coordinate. Click on the Image menu and select Examine. You will get a new window on the right-hand side.

Now move the mouse pointer over the main image, hold down the left mouse button and move the mouse around. Can you see what it is doing? We call this the Magnifying Glass.

You can use the slider to change the magnification ... Try this.

You can also get the coordinates of the point in the middle of the magnifying glass. Move the mouse pointer over the object you have found (remember to hold down the mouse button).

Underneath the slider you will see something like "X=145, Y=367". These are the coordinates of the object. Write them down, together with the title of the image (you can get this from the title-bar of the LTImage window).

Measuring Brightness

You should now be comfortable with exploring the images using the software. Don't forget that there are several images for you to look at. You should look at all of them and explore them all.

When you are happy with displaying and exploring the images, you are ready to find out some more about Measuring Brightness.