MetaGuide is a video-based tool for precise collimation using the in-focus diffraction pattern of a star. MetaGuide also autoguides and has several novel features that allow optimal guiding of mid-range mounts under typical seeing conditions. MetaGuide can provide insight into both the optics of your telescope, and the tracking behavior of your mount.
MetaGuide allows me to obtain sub-2" fwhm stars with a Celestron CGE and 11" SCT at 2800mm f.l. and 0.45" per pixel. The key is an accurate and low latency centroid that can be chased aggressively to overcome gearbox and bearing noise. This pushes autoguiding of a mid-range mount into a realm of performance that normally requires adaptive-optics.
MetaGuide is free, easy to use, works with any type of telescope, and most video cameras.
MetaGuide has many unique features, such as realtime measurement of flexure between two telescopes. This allows direct observation and measurement of flexure and mirror flop. MetaGuide also has a novel proactive guiding feature that locks onto specific high frequency gearbox or gear tooth terms that can be more of an issue than periodic error. MetaGuide also uses a novel form of "Lucky" centroiding to help determine a more accurate centroid that can be guided aggressively.
MetaGuide is highly quantitative, and provides live measurements of the radial profile of a star and its full-width at half-maximum for comparison to diffraction theory. It also measures drift, to aid polar alignment.
Although based on video guiding, MetaGuide can stack frames to create the effect of a long exposure that reaches faint guide stars. It also finds faint guide stars in the field and highlights them automatically. This avoids the user having to squint at the screen to find a guide star and then select it. When the guidestar is not faint, MG does not simply stack the exposures, but instead studies the centroid of each video frame and calculates the optimum centroid for the stack.
For the guiding component of MetaGuide, an ASCOM connection or other control of the mount must be provided (GPUSB, TOGA, AstroGene, LPT, and more).
Actual comparison of Airy patterns from several telescopes of different apertures, all shown at the same arc-second scale. Note that the small refractor and Maksutov have well-shaped diffraction patterns that make the stars look good, but the angular size of the stars is much larger than the telescopes with greater aperture. This is a direct recording of the likely reason that refractors appear to out-peform larger aperture SCT's.
Unzip the install file and run MetaGuideInstall_5_1_3.exe. You will be asked to install a Microsoft software patch. This is a needed step for many XP installations, but may not be needed for your computer. A pdf of documentation and a text file of updates will be installed in the MetaGuide directory. You can access the help using the menu of F1 from within MetaGuide.
Latest MetaGuide Beta version For people who want to test and experiment with the latest version. Unzip this file into the MetaGuide directory and overwrite any files that are there. Then go to a command line and type: regsvr32 GuideFilter.ax
MetaGuide 5.1 documentation alone, in pdf format, for perusal without doing the install. Detailed instructions and many examples, including a comparison of an SCT with a Maksutov. This manual is included with the installation.
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
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.
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.
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
Measure the dec. drift of the mount quickly so you can make rapid polar alignment adjustments to null out the drift.
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 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.
Copyright Frank Freestar8n 2010