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 Unless you have a  setup with a wide field of view you probably have considered doing a mosaic of the larger deep space objects (DSO's). There are a number of methods to accomplish this. I have been using CDC (Carte Du Ciel) as the planetarium program for many years. CDC has a feature where it allows you to define a mosaic grid over an object sized to fit you equipment. Save that  grid and reload it anytime you need it.

The latest version (4.3) has a Mosaic feature that makes it simple to setup and take pictures that  can later be combined to generate a larger mosaic. The process is straight forward. It’s assumed that  you have  finder rectangle set up in CDC that  matches your image train. 

Make a mosaic:

  1. Launch CDC and connect to the telescope.
  2. Select your target object. (In my example I used M31)
  3. Slew to the target and center it ( I do plate solving with AstroTortilla)
  4. in CDC click VIEW > MOSAIC

  • Click on the FINDER rectangle drop down box and select the one that  matches you setup. ( a mosaic pattern will be overlaid on the map)
  • Select the size of the mosaic and what ever overlap you thing will work best for you to stitch the images together. (I’ve selected a 2x4 grid)

  • In order to mark the center of the rectangles add a 1 arc minute finder circle to the display.
  • In CDC click on SETUP>DISPLAY>Finder circle (Eye piece).

    • Select an unused entry and change the FOV to 1.0 and click on the red button to turn it green .
    • Click on the OK button. A small circle should appear in the center of  each rectangle.

    You can now save the mosaic setup file on your computer by clicking SAVE on the mosaic setup window.
    This file can be reloaded by RIGHT clicking on the map and selecting FINDER CIRCLE > Load FROM  FILE.


    At this point you are ready to start taking pictures.

    1. Some earlier versions of CDC had a bug that failed to show TELESCOPE>SLEW TO CURSOR POSITION option when the chart was locked. Should this be the case, make sure that the chart position is NOT LOCKED either with the “anchor” button or the menu “TELESCOPE/TRACK TELESCOPE”.
    2.  Right click on one of the little circles and select TELESCOPE>SLEW TO CURSOR POSITION.  The mount should now move to the position.  At this point start taking images.

    If you will be taking multiple days to create this mosaic  you will probably want to keep track of which segments  have been taken. A pencil and paper will work or you could use the notes feature in GSS.

    Patrick Chevalley, author of CDC, has written a sequence program ( CCDciel ) that allows you to program what object to take and how many images to take of that object. It also allows you to import the mosaic file you created above and have the program take each section for you while you are in the house keeping warm.  CCD capture software intended for the amateur astronomer.
    It include all the features required to perform digital imaging CCD observation of celestial objects.
    Using the standard drivers protocol INDI and ASCOM it can connect and control the CCD camera, the focuser, the filter wheel and the telescope mount. Check it out here
    CCDciel download | .

    The end result would look something like this.

Using this method to capture the pictures is relatively simple. Processing the segments so they match their neighbor is something else.

(More to come )


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