ELBRUS CALIBRATING TUTORIAL

Step by step 3-stars calibration


This three stars calibration frees you from the tedious task of determining whether or not are your images 'reversed'.

1.- What you need is:
- an image where you can recognize three stars,
- for these three stars, their GSC catalog numbers, or their coordinates J2000,
- if the camera sensor pixels are not squares, you need to know their width and height.

2.- Run Elbrus.

3.- If not checked, check the 'Auto Threshold' at the left.

4. Go to the File menu, then click on 'A- Image path...' and select YOUR image.

5.- The image is loaded

6.- Now right click on the image. In the popup menu that appears, select the '1- Extract the stars' option under the 'Three stars calibration steps:'

7.- A red circle is drawn around the strongest selected stars. If you have less than three selected stars, verify that the 'Auto' check box is checked.

Now with the help of a planetarium, you must recognize some stars in your image. Choose three of them, not too near one from the other. They are the calibration stars. Copy from the planetarium the catalog number of these three stars. In our example we are going to use the stars GSC-4620-1347, GSC-4620-2083 and GSC-4616-300 (numbers 4, 1 and 3 in the image)

8.- Place the mouse arrow near the selected star number 4 (in our example), then right click, and then select the '2- Star A to calibrate (in a red circle)' option from the popup menu.
A white cross will be drawn on the star.

Right click on the selected star number 1 and select '3- Star B to calibrate' from the popup menu.
Right click on the selected star number 3 and select '4- Star C to calibrate' from the popup menu.

9.- Right click on the image and click on '5- Calibrate with three stars...'.
The 3 stars calibration window is shown.

10.- Select the sensor pixels shape. If the pixels are not square, you must type their width and height in microns.

11.- Now type the three catalog star numbers as shown. (If you are entering the coordinates, select the 'Using the coordinates' radio button.)

12.- Press the 'Compute' button ( DON'T FORGET ).
The computed calibration parameters are shown in the yellow boxes:
- The image angle orientation,
- The image 'reversed' status as determined by this calibration,
- The pixel size in arcseconds.

13.- Click the 'Apply' button to accept the new calibration.
The new values are now saved in the parameters file.

You can now proceed with the next step: Now I can solve my images

Or go back to : Introduction

(Updated February 10, 2009 Alfonso Pulido)