MetaGuide Troubleshooting


What do do: Problems with camera or mount connection and calibration




FIRST: The camera must operate in VIDEO mode with a DirectShow or WDM driver


MetaGuide will not operate with typical ccd or guide cameras that do not also operate in video mode - so the first thing to check is that your camera is supported. There are a number of commonly used guide cameras that do not have such a video mode and despite their popularity, they will not work with MG. MG is designed around the advantages of video for guiding and collimation, due to its high frame rate and low latency. Having a good monochrome, digital video camera serves many purposes in astronomy - including collimation, guiding, video finders, and more.




Camera Connection and Size Problems


When you connect to a camera, notice that the MG Setup page has a place to set CamWidth and CamHeight - corresponding to the *desired* width/height, in pixels, of the camera. Many cameras allow the selection of different resolutions, and MG will try to connect to the camera with the value that is a best fit to what you request there. The numbers you enter need not be exact, but if you know the resolution you desire, you should enter it as accurately as possible.

When you start MG, if you have more than one camera available, you will be presented with a list of cameras from which to choose. If you do not see your camera listed, make sure the camera has a

If the camera view is upside down it may still work fine for collimation and guiding, but if you want it reversed, press the UpsideDown button in the Setup dialog.




Mount Connection Problems


MetaGuide can connect to most mounts via ASCOM, but it can also connect directly to many autoguiding devices without ASCOM. Note that you can have an ASCOM connection to a mount even if you guide it with a separate device/connection - which allows MG to read the declination and other values.

MetaGuide used to require special handling of ASCOM mounts, but now it should connect in the normal to any ASCOM driver that supports PulseGuide for guiding. Some mounts used to require connection through "Generic Hub" but that should no longer be needed.

To test the PulseGuide connection to the mount, use the handcontrol or some other method to get a live display of the RA/Dec. values of the mount. Then open the Setup dialog in MG and try pressing the N/S/E/W buttons and watch for small changes in RA/Dec. Each press will cause a 1 second pulse guide in the corresponding direction. This motion will be very small so don't expect anything big - but you should be able to see some response indicating a good mount connection. Dec. motion may not be responsive due to backlash, so RA may be best to use. You may also be able to have a helper listen closely to the mount to hear the 1s pulse commands, and in that case declination may be more easily noticed because the dec. motors are normally off - and would only turn on due to a pulseguide command.




Calibration Problems


Sometimes the Calibration procedure will give a warning that the CalFactor is far from one. This may not matter at all and autoguiding/collimation will work fine - but it is preferable to avoid the warning. If you get the warning, make sure the pixel size, focal length, and Barlow factor are correct. If the camera is operating in a reduced resolution mode, make sure that any binning involved is included in the pixel size. Also make sure the declination value is correct - either if it is set manually or automatically via ASCOM. Similarly, make sure the autoguide rates are correct.

A calibration factor from 0.5 to 2.0 will probably work ok, but be prepared to tune the autoguiding parameters such as aggressiveness to compensate for the issue. If it thinks the focal length is longer than it is, then any error will appear *smaller* than it really is, and you may need to boost aggressiveness.

If you are only collimating and not guiding, the CalFactor will just affect the size of the expected Airy pattern. If you get a view of the Airy pattern and the first ring shows in the plot, you can use it as a "ground truth" measure of the pixel scale. Any difference between the simulated Airy pattern and the true one would indicate an error in the CalFactor, and you can manually change the CalFactor until the Airy pattern matches.

If you have checked all values and the CalFactor is still far off, try setting it to one to see if the guiding and tuning seem to work better.

Some mounts connected via ASCOM appear to cause an error in CalFactor. I recommend autoguiding with a direct connection to the mount with a hardware timing device for good pulseguides - either with the st4 port on the guide camera, if supported, or a TOGA or AstroGene device.




Other Problems


  • If the view is upside down, it shouldn't affect guiding, but you can press the Upside Down button in the Setup dialog
  • If many of the buttons are missing on the screen, switch to Advanced mode in the Settings menu
  • If you can't lock on a star, try adjusting the StarThresh and LockRadius



When Things Don't Work Right


If things aren't working right, first joint the AstroGeeks Yahoo group. and see if your question has been addressed in the past. If you still can't find an answer, recreate the problem in MetaGuide and then shut it down and send the two debug logs that are generated in the MetaGuide directory:

  • MGDebug.log
  • MGVidDebug.txt

These files are overwritten every time you run MetaGuide, so be sure to save them after a bug has occurred, and after you shut down MetaGuide. You can post them directly on the group in the files section in a folder with your name. The MGDebug.log file has information on the general operation and calibration, while the MGVidDebug.txt has information on connecting to the video camera. If the camera is connected and works fine but a different problem has occurred, there is no need to send the second file.




Support

For support, please send feedback and questions to the AstroGeeks Yahoo group.

Contact (spam encoded address): freestar8n *at_t& yahoo _d_ot_t+ co*m

Guiding

Low latency guiding with video. Quick and accurate corrections for mid-range mounts.

Achieve tighter and rounder stars than with long guide exposures and standard centroid algorithms.

Let MG find and select faint guidestars as they come into view so you don't have to squint at the screen.

Collimation

Collimate using a star with the telescope aimed at the correct angle to the sky. Just center the coma dot on the star while the mount re-centers it. In better seeing you can use high power and collimate on the in-focus diffraction pattern.

Take an annotated and scaled image of your collimated star to show how well your star diffraction pattern matches theory.

Seeing measurement

Measure size of the star spot as it moves around over each 2-second interval, with live plots. Can be used as a dedicated seeing monitor with a telescope, or just to check seeing conditions

Drift alignment

Measure the dec. drift of the mount quickly so you can make rapid polar alignment adjustments to null out the drift.

Periodic error logging

Log periodic error in detailed formats for analysis in other tools. These measurements are taken every 0.5s with an accurate centroid, allowing high resolution studies of your mount behavior including gearbox and other noise. This may be the most important type of error for good guiding compared to the slower and more easily corrected terms.

GuideView mode

GuideView mode lets you watch the live guide corrections in video mode so you can see the small, fast motions of your mount that are the key to getting tight stars.