Click on the “DOT GUI” icon on the desktop to start the GUI.

When clicking on the small camera image thumbnails at the left, you open a window with the live camera images. The live view allows you to zoom in and out and view the intensity, RMS and histogram. Contrast can be adjusted automatically (press ‘C’ to activate the autocontrast) or manually by using the mouse left/right buttons to select the position of the red/green bars displayed in the histogram. Contrast varies only for displaying purposes, it does not affect stored images.

The live display also has a frame selection mode (press ‘S’ to toggle this, or click on “Frame selection” in the “Extra” menu). Again, this only affects live dispay, not the stored images. It is best to keep most live displays in frame selection mode, in order to reduce the strain on the network and on jeff to display the images.

The GUI allows you to write a script which will perform the actual observation.


If you need to give a command to all camera computers, you can use the cssh cameras command from a shell, or click on the “ClusterSSH cameras” icon on the desktop. A terminal window is opened for every camera computer, and one extra small window. Typing in the small window will send whatever you type to all the camera windows.


To start the guider, click on the “DOT Guider” icon on the desktop. A full-disk image of the Sun should appear with a green grid on top of it. A red rectangle shows you where the telescope is currently pointed. A purple circle indicates the current target. Yellow circles indicate stored targets. You can right-click on the image and select “Go to this position” to set a new target. You can also make small adjustments to the target position with the “North”, “East”, “South” and “West” buttons on the left. The guider has 5 modes, which can be selected with the top left buttons:

The Stop, Dark, Flat and Center modes do not change the target position, so if you click on Track it will always go back to what you previously selected.

You can also draw a rectangle by middle-clicking and dragging on the image. This rectangle can be used for making mosaics with the DOT.

If the guider is not working correctly, press Stop. Then:

If you see the red rectangle, then try pressing Track. If the telescope still doesn’t move, switch the beige box to “Tower” and immediately call DOT staff.


In the top screen, open a terminal and start IDL. Type pd_focus. A window should appear with two halves showing granulation. There are three numbers at the top of the window. The middle number is the relative exposure, and should be close to one. Click on one of the granulation images, and then press + or - to increase or decrease the midddle value until it is as close to 1 as possible. Click on “get” to get the current position of the focus motor. You can now press ‘—’, ‘-‘, ‘+’, and ‘++’ to change the focus position in small or big steps. The inner sliders should be at the same height when you are in the correct focus position. Note that the focus program only works corrrectly when:

Once in a while you should refresh the flats and darks for the focus camera. To do this, stop pd_focus and IDL. Then, in a terminal on the focus machine, type rm FD*.save, start IDL and then pd_focus again. You will be asked to take flats and darks for the focus camera. Click on “Yes”. When asked to defocus the telescope, first set the guider to “Flat” mode, then click on “OK”. After a while it will ask you to go to the dark position, set the guider to “Dark” mode, and then click on “OK”. When it is finished, click “Yes” to save the flats and darks, and set the guider back to “Track” mode.

The intensity of the Sun can change during the day. If the top middle value start deviating too much from 1, change the exposure again (see above).

Rebooting computers

If a computer hangs, and you cannot log in to it with ssh, use the reset button. If you can, log in to one camera machine with ssh, or to all with the ClusterSSH method (see above). To restart the camera software, use the following command on the camera computer:

invoke-rc.d dot-ccd restart

To reboot the computer:



On jeff you can run IDL in any terminal window and launch the programs in any directory you are place. In the other computers for the cameras you should be connected as dot user (not as root) to be able to run IDL. Type exit to go out from IDL.