In this chapter and the next we will explain how you can use the Asteroid Catcher B-612 (AstCat) in order to detect asteroids. Please also refer to the list of icons in chapter 10.

First of all, double click on "AstCat.exe" in NEA folder to start the program. If you have not yet registered your group name and setting initial values please do so first (refer to 3.5) before you proceed any further.

Next, Click on "START" button. You will see the following window. This is the window for loading image data.

NB: There is a "return" icon on most of your windows. Alternatively, you can use the close icon at the upper right corner of your window to close your current window.

5.1 Loading reference image

Load the first image (Reference image) by clicking on at the top of your window. An image loading dialogue will be displayed. Choose your target image file and click on it, or alternatively type in the file name directly.

NB: Loading image files takes a lot of time, as they are all large files. It may take a few minutes to load one image depending on the processing speed of your PC. Please be patient even if the screen appears to be stopping.

Once the first image is loaded, the following window will be displayed.

The coordinates (right ascension and declination) of the center of the image and other information are displayed. Click on "automatic matching" and match your image with the star catalog.

Automatic matching with the star catalog is the process whereby stars on your image data are checked with the reference stars on the star catalog and the exact location of your image on the night sky is determined.

If this automatic matching is successful with the first image data, then please load images 2, 3 etc. Automatic positioning of these images with reference image (the first image) will be carried out.

If you want to delete a loaded image click either on icon (currently displayed image is deleted), or on icon (all loaded images are deleted). If your image currently on display is the image 1, then clicking on icon will delete all currently loaded images.

NB: You can output the image currently on display as a BMP (bit map) file by "output image as BMP" icon . Original images are of FITS format and some of image processing software may not be able to handle them. In that case this is a useful function.

5.2 Manual matching with star catalog

If automatic matching with the star catalog fails, you must do manual matching. It is rarely necessary to do this. However, occasionally if images are taken around the Polar Star (declination larger than +89 degrees) , or if images are not very good, automatic matching may fail.

In that case you must compare your image with the star map (map of the star catalog data) in the following way so that both are matched.

If automatic matching fails, you will see a window shown above. You click on the OK button on the message box and a new window will show up. It is within this window that you do your manual matching. This window shows your image on the left and the star map on the right.

First of all, you must check if both images are of the same area of the night sky by the resemblance between the image and that of the star catalog. It is possible that the values of right ascension and declination are wrong if there is no resemblance between the two images.

The star catalog is partitioned with a blue square that indicates the field of view. This is for your ease of operation and you should not differentiate the inside from the outside. You should select 4 pairs (or more) of the same stars. These pairs should be evenly located over the entire area of your image.

Having decided on these paired stars you then must click on them both on the image and the star catalog in the same order. Therefore, you are advised to click on your target stars alternately between the image and the star catalog. Clicked reference stars will turn red. If you wish to cancel your selection you only need to click again on the selected pair. After the selection of pairs, clicking on "manual matching" icon will start the process of matching the image file and the star catalog.

If you click on "reference stars" icon after your matching operation, those pairs with good matching accuracy will appear red and those with significantly less accuracy will turn blue. If there are red pairs evenly across the screen, your manual matching is a success and click on "return" .

If you click on table of residuals icon you will be able to know the amount of residual between your image and the star catalog. Even on this manual matching window you still have "Automatic matching" icon . This has nothing to do with manual matching and it starts automatic matching, but it allows you to know the result of automatic matching.

If you click on "initialize" icon selected (or marked) stars are all cancelled. You may use it for selecting your reference stars all over again.

If you click on "Match with star catalog" icon in the image loading window then a window for this operation will appear. Normally, images are automatically matched with the star catalog when they are loaded. You may use this icon in case automatic matching fails to take place.

5.3 Display option

You may use icon for adjusting contrast and others.

Contrast:

Default value is 10. Larger values will lead to smaller contrast.

Sky Value:

Larger values of "Sky Value" will brighten up stars, but also increase noise level.

Test display:

This is done by "Show test display 1" or "Show test display 2" icons. At first, "Test display 1" will display currently adopted setting values, but you can change them. If you click anywhere on either display you can use values set for that display.

Apply to all images:

Setting values will be applied to all images and redrawing of images will be made.

Use default setting values:

This is used to return to default values.

5.4 Display image information

If you want to know information on your image please click on icon.

By clicking on image 1 to image 6 you get information on each image. Clicking on an image number that has not been loaded will not cause any change in the display.

Number of recognized stars

This is the total number of objects recognized as stars upon scanning the image.

Brightness constant

This is a constant used to calculate the magnitude of stars and is obtained from the magnitude listed on the star catalog and the CCD brightness. From this you can calculate the magnitude of your target star as:

Magnitude = Brightness constant - 2.5 times log (brightness)

Table of residuals

With this table you can find the residual of matching between the images and the star catalog.