Observing steps

  1. Switch on the computer screens. Switch on the DOT power supply, System Power (first) and Motor Power (after red led is on).

  2. Run DOTgui, poswatch (IDL widget), ClusterSSH programs (see ?Acquisition software).

  3. Calibrate the Sun center * Manual control: Control Room. Use the DOT Halpha Full disk window (poswatch). Move the red box over the solar disk by using the East-West-North-South steps to four positions around the solar circumference. Use the Gband as a reference to to place the solar limb passing by the center of the green xy axis for each position. You can move the telescope faster to every position with the “Go to this position” option in the menu (click on mouse right button) and then use the East-West-North-South steps for the fine tuning. For every position use the Rim 1, 2, 3 and 4 boxes to save the coordinates of every point respectively. Press the Compute center button. * Finally click on apply correction.

  4. Go to the desired target (SOHO coordinates). Open terminal window and enter for example:

    guidergoto 600 0

  5. Run the focus program in screen 2. ** Open IDL in a terminal window and launch the program


** Change focus position +/- (5 steps) and ++/— (10 steps). the RMS for the left and right images are roughly the same. If left image looks better than the right one use +, otherwise -. To do a scan for finding the best focus position select the camera you want to use (e.g scott) and run into IDL:


Remember that this works when the seeing is reasonably good.

  1. Use the DOTgui interface -> File, Open and go to the directory where the scripts are located: /home/dot/guus/filter-control/gui/Scripts (you can also Search for the script you want to run). Run IDL script Align_init for post-alignment calibration. This should be done in a moment of good seeing so that we get a reliable alignment calibration with no distortion effects. Alignment must be done in a quiet region, preferably near the center of the Sun. Can be done before or after observing. Click on “Start measurement” to run the scripts, which selects the wavelengths near the continuum. Then set “Filename” to Align, “Image count” to 50, and click “Burst”. Then defocus the telescope, set the guider to “Flat”, and click on “Burst” again to save flats. Then set the guider to “Dark”, and click on “Burst” again to save darks.

  2. Run IDL script Align_reset (or put the values manually according to the particular settings you have previously defined in your run.) CaFilter Tune 3968.550 HaFilter Tune 6563.00

  3. Exposure time of the cameras should be less than 10 or 12 ms. Interval (frame rate) could vary (a reasonable number is 0.095). You put these values manually (in seconds) in the boxes and then press Set to load the value.

  4. Halpha line center calibration. * Calibrate every time you change the target (due to Doppler shifting). * Run IDL routine to calculate the line fitting to get the center value:


Set this value manually (in Ångstroms) in the box HaFullDisk.

  1. In the main DOTgui interface open the script to edit Halpha scanning: Ha5pt (scanning for 5 points). Calculate the values for the positions of the 5 points by using the line, for example 350 mA and 700 mA at each side of the line core. * Edit the script filter position lines with the values calculated above. duration 30 seconds filename PUTNAME to identify the created files with the given name. * Save script as //00_today// or any other name.

  2. Observe a nice region of the Sun ** Repeat = number-of-cycles and Start measurement. e.g Repeat=200 would correspond to 100 minutes if the duration of every cycle is set to 30 seconds.

  3. Flat images * Defocus the telescope. Cameras control. Repeat = 1. Use the PC Guider window (Raptor Display) to move the telescope (i.e upside down) while recording the flat images. (the telescope should be moving while recording every burst ). This is done to avoid solar contrasted structures (e.g. sunspots, pores, etc) while recording the flat images. * Start measurement

  4. Dark images * Go to dark position (press mouse right button on the HalphaFullDisc guider). Cameras control. Repeat = 1. * Start measurement.

  5. Linearity calibration for the cameras (crucial for the Ca camera). * Defocus the telescope. Set the exposure time for the camera in a close-to-zero value. Interval = 0.150 (7 fps) in the DOTgui interface (make sure you set back the interval after burst). * Open a terminal window and run in IDL

    print,linearity(‘scott’,0.001,/verb) * Choose with the mouse (left button) the value where you want to set the maximum of the range. * Write down the output values.

PDF Walkthrough

Here are PDF Walkthroughs of the calibrations and observing procedures. It is the same information as here, but with a little more step-by-step detail.

PDF walkthrough calibrations

PDF walkthrough observing