Tools and Utilities
Manual Guide
Auto-Select Star
Calibration Data
PHD2 Server
Drift Alignment
Lock Positions
Comet Tracking
Equipment Profiles
Simulator Parameters
Manual Guide
If you are connecting to a new mount and are encountering calibration problems, you will probably want to be sure that PHD2's commands are actually getting to the mount. Or you may want to nudge the mount or experiment with manual dithering. In the 'Tools' menu, click on 'Manual Guide' and a dialog will appear to let you move the mount at guide speed in any direction. Each time you press the button, a pulse of the duration specified in the 'Guide Pulse Duration' field will be sent. The default value is the 'calibration step-sze' set in the Advanced Options dialog. If you are debugging calibration problems, listen to (rather than watch) your mount to determine if the mount is getting the commands from PHD2. The idea here is just to figure out if the mount is responding to PHD2's signals. You won't be able to see the mount move (it's moving at guide speed) but you may be able to hear it. Other options include watching the motors themselves or attaching a laser pointer to your scope and aiming it at something fairly far away (to amplify your motions). If you have an adaptive optics device attached, you'll see separate move buttons for both the AO and the secondary mount.
Dithering is used primarily with image capture or automation applications, usually through the PHD2 server interface. However, you can do manual dithering or experiment with dither settings using the controls at the bottom of the dialog. The 'dither' amount field at the left controls the amount the mount will be moved , in units of pixels. You can scale this amount - i.e. multiply it by a constant - by using the 'scale' spin control to the right. These two controls establish a maximum amount of movement that will be used for dithering - the product of 'scale' X 'dither'. When you click on the 'Dither' button, PHD2 will move the mount by a random amount that is less than or equal to the limit you have set, in one of the north/south/east/west directions. The 'RA Only' checkbox will constrain the dither adjustments to only east or west. Obviously, if you are doing a manual dither in this way, you'll want to be sure your imaging camera is not in the middle of an exposure.
Auto-Select Star
Clicking on 'Auto-select Star' under the 'Tools' menu, or using the keyboard shortcut of S, tells PHD2 to scan the current guide image and identify a star suitable for guiding. PHD2 will try to select a star of sufficient brightness that is not near another star and not too close to the edge of the frame. The selected star may appear overly dim on the screen, but this is usually not a problem. You can use the Star Profile tool to examine the properties of the selected star - it should be non-saturated with a sharp profile, the same properties you should look for when choosing a guide star manually. The auto-select process is not infallible, so you may need to select a star yourself if you don't like the automated result. If you want to use Auto-Select, you should definitely use either a bad-pixel map or dark library to reduce the likelihood of PHD2 mistakenly choosing a hot pixel.
Manual Control of Calibration Data
Calibration data is saved automatically each time a calibration sequence completes successfully. The use of the calibration data has been described elsewhere (Using PHD Guiding), including options for restoring calibration data from an earlier time or "flipping" it after a meridian flip. You access these functions using the 'Calibration' sub-menu under the 'Tools' menu. Two other calibration-related items are shown there, namely the options to clear the current data or to enter calibration data manually. The "clear" option accomplishes the same thing as the 'Clear calibration' checkbox in the Advanced Dialog - it will force a recalibration whenever guiding is resumed. The 'Enter calibration data' option should be used only under very unusual circumstances and only if you're sure you know what you're doing; but it is available as a matter of completeness. If you click on the 'Enter calibration data' item, you'll see a dialog box that allows input of relatively low-level calibration data. This data might come from a much earlier session, perhaps extracted from the PHD2 guiding log file.
PHD2 Server
PHD2 supports third-party imaging and automation applications that need to control the guiding process. Stark Labs' Nebulosity program was the first to do this, but other applications have subsequently been produced. By using the PHD2 server process, image capture programs can control dithering between exposures or suspend guide exposures while the primary imaging camera is downloading data. To use these capabilities with a compatible application, you should click on the 'Enable Server' option under the 'Tools' menu. The server interface has been reworked substantially in PHD2, and it's now possible for an application to control most aspects of PHD2's guiding operations. Documentation for the server API is available on the PHD2 Wiki.