IS 2008-12-18 First version.

How to track moving objects

Quick summary:

  • preset to the object
  • bo-at-ce
  • bo-mo-sta (with 1, 10 or 100 times rate)
  • bo-mo-sto (direction found)
  • place the box and move telescope or guide probe to get guide star in box
  • ag-on
  • bo-mo-star (with actual set rate)
  • The star box can be told to move across the autoguider screen with a speed that corresponds to the object set rate. At the same time telescope set rate is set so that the autoguider only has to correct for the pointing errors. Since the limitation here is the distance the star box can move between the edges on the autoguider display this is useful for a maximum movement of about 60" during an exposure, relative to the stars. The rate is given in RA/DEC coordinates so the RA movement relative to the stars decreases the closer to the pole one gets.
    Do the preset to the object to get a proper guide star. If You are not sure of the direction the box will move in, just put the box at center with
  • box-at-center

  • and give
  • box-motion-start (or bo-mo-sta)

  • with the desired rate. Look at status page 2 about middle right to see how long time it takes before reaching an edge. If the movement of the box in the autoguider screen is slow then just try it with a factor 10 or even 100 to clearly see the direction. Status page 24 can also be used to see the box position. When the direction is established then do
  • box-motion-stop (or bo-mo-sto)

  • and place the star box at a proper starting position. Move either the telescope or the guide probe to put the guide star in the box, then do
  • ag-on
  • box-motion-start

  • with the object RA/DEC rates in coordinates. Check status page 2 for the time before an edge is reached. If this happens during autoguiding the box motion and autoguiding will automatically be stopped and the telescope will continue with blind tracking with the applied set rates. The box can now be placed at the opposite side and the guide probe moved to once again place the guide star in it, then ag-on and bo-mo-start again (use command recall with arrow keys). Note that this can be repeated as long as the guide probe does not reach its own limits and it does not obscure the image.
    When all is done do
  • bo-mo-stop
  • Preset to the object and use

  • set-rate

  • with the actual RA/DEC rate in coordinates. If the object moves very fast when passing the earth then it might be necessary to give new set rates a few times every minute.