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Self Guiding an LX200 with an MX7C Using Star2000 | ||
  STAR2000 Setup For LX200 There are 2 ways to connect S2K to the LX200 – you can connect it to the CCD port of the LX200 or to the RS232 port, either way the other end needs to be connected to the COM port of your computer. Go to the end of this section for setup for each way. I will assume that the object of interest is in the centre of the image and that the telescope and ccd camera are focused. 1) Connect the lead into the RS232 port of the telescope and connect the other end to the LX200 port of the S2K box, or connect the lead into the CCD port of the telescope and the other end to the port not marked LX200 on the S2K module. 2) Use the AstroArt Camera Control to select the setup tab and set the binning to hi res selfguide. 3) Select the image tab and take an exposure of 5 seconds. 4) Draw a small rectangle around the brightest star in the field, making sure that there are no other stars in the close vicinity. 5) Select the Focus/Guide tab and make sure the Auto box is checked, the Correct Dark Frame box is not checked. Set the binning to 2x2 and the guide exposure to 2.0 seconds. 6) Set the telescope hand controller speed to ‘Guide’. 7) Select the Image tab and press the telescope button, check your settings*. 8) Select the Focus/Guide tab and click the Guide button. A image will appear with your guide star in the centre, now click Mark Guide Star and click the Telescope button. 9) You are now guiding, if you are over compensating your guide corrections, then increase the pixels per second value for that axis, and decrease if you are under compensating. If you lose the guide star quickly then there are two main reasons. You have not got the hand controller speed set to Guide You may need to check the box reverse next to the pixels per second for the axis that is going haywire – some focal reducers or barlows flip the image and this will reverse the direction the telescope needs to go. Settings Using the LX200 RS232 port: On the telescope button on the image tab, select the following. Starlight Xpress Relay Box – LX200 Classic and Com 1. Using the LX200 CCD port: On the telescope button on the image tab, select the following. Starlight Xpress Relay Box – ST4 Mode and Com 1. The X an Y boxes are for pixels per second that your telescope will move, so this can be different in different parts of the sky or when you use different focal lengths, so for each setup it is worth measuring. Take an image of a bright star, the using the hand controller in guide speed, move the telescope for 5 seconds left or right. Measure the distance the star moved in pixels. Then divide that number by the seconds – 5, to get the seconds per pixel in the RA axis, do the same for the dec axis. The ignore drift boxes are to try and stop the camera from chasing the seeing, usually setting of 6.0 are adequate, but if the seeing is very bad and the star is jumping all around the guide window, you may want to increase these values. All these do is say ‘do not move the telescope if the movement is less than 0.4 pixels and also don not move it if it is more than 6 (as this would usually be a cosmic ray or something). Swap XY is for swapping the axis of the camera should you want to mount the camera with its width parallel to the Y axis instead of the X. The Adaptive Guide box is for guiding in poor seeing, I have never used it as when the seeing is that bad then I either give up or change the focal length. The ‘Pause After Guide’ is for when your telescope is moved by the guider, sometimes the star keeps moving while the gears in the mount all catch up with themselves, this stops another guide image from being take for x seconds after the guide movement – on an LX200 I have it always set at 0.2 sec. The DEC Backlash should be set to Automatic Backlash Correction (which I believe means no backlash correction. LX200’s are notoriously bad for their backlash and mine is the same. I have the backlash set on the hand controller to maximum – 99 and I still have 1 or 2 second backlash, unfortunately it is different in different parts of the sky. So to get over this, my polar alignment is very slightly off on purpose, that way the telescope is permanently moving north at a rate of about 0.5 pixels a minute. That way the telescope never has to reverse DEC direction and therefore all backlash is eliminated. My AstroArt Settings  | ||