MetaGuide 4.0.8 with ASCOM Support Frank Freestar8n, September, 2008 http://www.astrogeeks.com/Bliss/MetaGuide This document describes some of the new features and changes in MetaGuide 4.0.8. Please consult the full MetaGuide manual for instructions on the core features. NEW FEATURES: 1. Revamped ASCOM support for autoguiding 2. Realtime flexure measurement with 2 web-cams and two copies of MG running at same time 3. Shift tracking allows guiding on comets and correcting for flexure by providing a guide offset relative to the guide star at a specified rate 4. Improved centroiding and guiding 5. Hot pixel removal 6. Improved handling of multiple web-cams, with selector dialog 7. Better measurement of star drift 8. Guidestar is highlighted with crosshairs 9. Guidestar can be 'locked' so it is not confused with other star in field. 10. Better logging of more complete information - including FWHM 11. Multiple telescope/detector setups can be stored and loaded 12. More heuristics to help with Dec. guiding, including backlash correction and minimum move 13. Allow specifying frame rate of web-cam 14. Allow blocking corrections in N, S, and E/W. KEY CHANGES IN USABILITY Users may now specify multiple .ini files for different telescope/imaging combinations. These files are NOT updated and saved automatically when changes are made, so the user must remember to save - particularly after doing a calibration, if the calibration is meant to be used again. There is a new File menu button for saving setups - including a Most-Recently-Used list. I suggest creating a directory with several different .ini's and loading them as needed. If more than one web-cam is attached, a dialog will appear allowing selection of a specific one. This dialog only appears if there is more than one camera avaialable. INSTRUCTIONS FOR NEW FEATURES ASCOM Support: The autoguiding features of MetaGuide now support the ASCOM interface, but direct connection to GPUSB and parallel port are still available. The ASCOM environment is not required to be installed unless an ASCOM connection is needed. You must install the latest ASCOM and the appropriate driver for your telescope if you intend to use ASCOM autoguiding. The telescope must be equatorial, and must support PulseGuide commands. To enable ASCOM, open the Scope Setup dialog and in the selector for ASCOM/USB/LPT guiding, select ASCOM from the drop down list. Then click the ASCOM Chooser button to select the appropriate driver for your telescope. After you select, a connection to the telescope will be established. ASCOM handles the Dec. and R.A. Guide rates specially in the Scope Setup dialog. Normally the user sets these values to match the settings of the autoguide rate of the mount. If ASCOM can query the mount’s autoguide rates in R.A. and dec., it will overwrite the values in the Scope Setup dialog. If these rates are incorrect, i.e. differ from the rates issued during a PulseGuide, the calibration and aggressiveness values may be wrong. ASCOM will also query the declination prior to running calibrate, and overwrite the values in Scope Setup. To test the ASCOM connection, try pressing the R.A. Manual Control jog buttons in the setup dialog. Flexure Measurement: Flexure is a difficult thing to measure, but MG has features that should make it easier. You need two web cams, one attached to the main OTA and the other to the guide OTA. Start MetaGuide and select one of the two web cams. Then start another copy of metaguide and select the other web-cam. You should now have two copies of metaguide running, and under the covers they are aware of each other and communicating. Choose one of the MG's, preferably the one associated with the longer focal length telescope, and calibrate it normally. Once calibrated, press the Flexure button in the main dialog, and it will open a new dialog showing a live view of the stars in each web-cam as red and green dots. Press calibrate, in the flexure dialog, and follow the directions on manually moving the telescope 3 times while keeping the star in view. This co-calibrates the two web-cams so their differential motion can be tracked. This measurement is so delicate that even though the two cameras are calibrated, the star should be kept centered in the main view for greater accuracy. To do this, press Guide to guide with the main web-cam, and then press ZeroDelta in the flexure dialog to begin tracking the differential movement. You can press Log Flexure to output a log of the differential movement. Flexure is shown as a live plot conveying the flexure rate and direction. This rate could be 0.01"/m up to 1"/m, for example. You can also press on different parts of the guidescope or OTA and watch the deflection. Other things you can do: Try centering on a star and then press zerodelta. Then move the OTA to another star, center it, and read the delta. This shows the shift caused by the change in angle of the scope, and you don't have to wait for a star to move to measure this. Another thing to try is to zero it on a star, then move the ota way down, then back up to the same star. Any shift is due to hysteresis of some kind - probably mirror "flop." Figure 1 Flexure screen showing two instances of MetaGuide from separate web-cams, and the corresponding flexure display. The display tracks both absolute differential motion and rate at a fraction of an arc-second per minute. Shift tracking: This allows tracking a comet or compensating for flexure by guiding on a guide star, but slowly and controllably drifting away from it. You enter the shift rate in E and N directions, and while guiding on a star, the guide star will drift at exactly that rate. This lets you guide on a bright star while tracking a comet, or compensate for an estimate of flexure. Even if the rate is not known exactly, a great deal of flexure can be removed by an approximate value. Hot Pixel Removal: Just follow the directions in the Setup dialog after clicking Kill Hot Pixels. The hot pixels should disappear without a trace. Lock Star: Stars that appear in the view are immediately selected as guide stars, choosing the brightest one automatically so the user never clicks anything. In case another star is in the view that confuses this algorithm, LockStar will force the current star to be tracked and will block out other stars. If this is clicked, the star must not move too quickly or it will be lost. This can also be useful during calibration, when a nearby bright star drifts into view. Locking on one star will avoid this problem. Dec. Lash: There are now ways to improve declination guiding. You can provide backlash correction in milliseconds, and you can specify a minimum overshoot (dec. reverse) before a correction is applied - amounting to a dead zone around 0. You can also block corrections in the N or S direction. Frame Rate: This will set the approximate start-up frame rate of the camera. If the specified rate is not supported by the camera, a nearby one will be chosen and the actual rate will be displayed in the main dialog. For Lumenera cameras this rate can be as low as 7.5 fps, reaching faint guide stars. KNOWN ISSUES Swapping between USB guiding and ASCOM guiding may cause trouble. Some ASCOM drivers do not appear to return the correct value for the augoguide rates. Some ASCOM drivers require first connecting to POTH, and then to the driver. INSTALLATION ON VISTA MetaGuide has been installed and tested on Vista machines. The installation requires setting administrator permissions both for the user and for the install application.