MetaGuide collimation and guiding software update

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 a telescope and the tracking behavior of a mount.

MetaGuide allows users to obtain low 1" FWHM stars with a Celestron CGX-L and 11" SCT at 2800mm f.l. and 0.28" 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 astro cameras.

MetaGuide has many unique features, such as real-time 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 users having to squint at the screen to find a guide star and then select it. When the guide star is not faint, MetaGuide 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 is required.

MetaGuide collimation and guiding software release: Version 6.1.7

• Bug fixes and performance enhancements to 6.1.0
• Completely updated and reworked manual
• Better camera support
• Collimate on the Airy pattern even in mediocre seeing
• Better guiding with a mid-range mount using low latency video and novel centroiding
• Don't just guide easily - guide well
• Simple, accurate calibration with a single button
• A very different way to guide with better results and tighter stars
• Watch your guidestar in realtime while you are guiding with the power of video guiding
• Monitor your guiding on a different computer over your local network
• Detailed guide plots updated every 0.5 seconds for better tuning
• Rotator angle support. Calibrate once, then change rotator angle and guide without recalibration
• Permanent hot pixel storage and improved hot pixel detection
• Integrated with NINA and Sequence Generator Pro
• Easily controlled from other apps, including Python
• Automatic handling of meridian flip
• Support for FlexRX tool to correct for flexure when using a guidescope.
• SEEING measurement
• FOCUS dialog
   

What does MetaGuide do?

• Allows a high-power view of a star and its diffraction pattern even when seeing is not ideal
• Shows a "coma dot" over the live star that guides collimation so the user just centers the dot over the star. This takes the guesswork out of collimation while keeping it interactive and real-time
• Compares the observed diffraction pattern with theory, including secondary obstruction effects
• Provides a simple "dump" of the raw and steady images of the star, along with a plot that shows how the stellar profile compares to theory, plus numeric values for the actual and theoretical FWHMs. This provides an objective and quantitative measure of a telescope's true performance, with less dependence on good seeing
• Measures flexure/mirror flop using two telescopes, two web-cams, and two instances of MetaGuide that link to each other
• Automatically re-centers the telescope during collimation so users can concentrate on the collimation adjustments without having to re-center manually after each change
• Acts as an autoguider with seeing effects partially removed from the error, so the "chasing of the seeing" is directly reduced
• Calculates centroid based on the live view of stars using a very different algorithm than simple "center of gravity."
• Provides graphical output and logs of drift and periodic error in a mount, including the "noise" that can be hard to remove with PEC (Periodic Error Correction).
   

How does it work?

• MetaGuide uses realtime image processing of the video stream to process each frame, find the star centroid, and output a realtime stacked version of the recent frames
• Bad frames are automatically culled from the stack without user intervention
• Normal autoguiding software assumes the guidestars are nice Gaussian shapes - but in fact they have broad and misshapen wings due to seeing. MG focuses on the central hot spot of the star in each video frame and guides on the centroids of these hot spots
• MetaGuide is written in DirectShow/C++ for maximum performance since the amount of realtime computation is significant
• The stacked view is magnified 4 times and aligned with sub-pixel resolution
• This stacked view is also used to determine guide corrections. Since this view has bad frames removed, the resulting error signal is a truer representation of the error due to the mount.
• The radial plot is calcluated based on the stacked image, allowing direct comparison to theory and calculation of FWHM
   

What are its requirements?

• MetaGuide requires only a camera that supports video and Windows computer for its collimation function.
• Most CMOS cameras are supported and some DSLR's with video drivers. The user can specify any resolution the camera supports. The main requirement is that the camera has a DirectShow or WDM video driver
• For the guiding features of MetaGuide, an ASCOM connection to the mount is needed. The mount must be either equatorial or on a wedge, and it must support PulseGuide
• A view of the diffraction pattern requires small pixels and benefits from a red or IR filter - and a bright star nearly overhead.
• You don't need to resolve the Airy pattern and rings to collimate, but it does make it clearer. If you can't see the ring you can still use the coma dot as a guide.
   

Frank Freestar8n Demos MetaGuide for Video-Based Collimation and Guiding

Download MetaGuide