Skywatcher Virtuoso (Alt/Az)
Features
This driver supports Alt-Az mounts, but it was tested with Skywatcher Virtuoso.
Basic functions such as Track, Sync, and Park/Unpark are supported.
General Considerations
How to start with a Virtuoso mount:
1. Before connecting, the telescope or the DSLR on the Virtuoso mount should roughly point to Polaris (use the Sync method later to finetune the position). In practice, align the mount to true North-South and point a pin to the local latitude. The manual latitude setting of the mount with buttons 2+3 are NOT needed, INDI works independently from the manual mount settings.
2. The driver assumes by default that the telescope/DSLR is parked. Set the desired unpark position in the settings and click on Unpark button (Main Control tab) to move the telescope to a starting (unparked) position. The telescope motion control will be fully operational after unparking.
3. There are two slewing modes for the telescope: Silent (slower-and-silent) and Normal (quick-and-loud). It is configurable, the Silent mode is the default.
On connection, the mount sets the controller time and location.
Before syncing the mount make sure that the correct side of the pier is selected in the Main Control tab.
When using the driver for the first time, ensure to set the telescope's aperture and focal length in the Options tab.
Software PEC
The Skywatcher Virtuoso mount does not have PEC implementation to learn and correct the mechanical errors, but the mount has a constant drift on the Alt axis downwards in tracking mode. This error makes impossible to keep the target in smaller FOVs (e.g. 40x30 arcmin with the shipped Heritage 114p telescope+CCD camera). The drift was checked and was found about 0.009 degree/minute. Support was added to the driver for this static compensation and it was named SoftPEC (software PEC). This feature is enabled by default for Virtuoso mounts in the driver.
How does it work?
- It should just work transparently out-of-the-box.
- The software PEC is enabled only if the mount is in Track mode. Over time, the mount driver correct the vertical drift with the SoftPEC value. The software correction does not change the position of the red mount cross-hairs in KStars during Track mode.
- When the Track mode is stopped, the SoftPEC is switched off and drift correction is reset. The red mount cross-hairs will jump position according to the real position of the axis encoders in KStars while the mount will not really move anywhere.
- If you have a small FOV (<= 1°-2°) because a DSLR or CCD camera is attached to a main telescope: the Virtuoso mount will be misaligned too much just by moving to a new not-near position. Do an "Capture & Align" with Sync "Solver Action" all the time before start a target tracking. When the target is locked well in the FOV by the beginning, the standard tracking with SoftPEC enabled in INDI will do a great job.
How to calculate custom SoftPEC value?
1. Start the mount according to the General Considerations.
2. Disable the SoftPEC in the mount configuration.
3. To calculate the vertical drift repeated alignment calculation will be done in the following steps.
4. Start track a target for alignment where the vertical Azimuth axis is mostly parallel with RA axis on the sky. You can check this in Stellarium, by switching on both with keys E and Z. Check where the vertical blue and orange lines are mosly parallel and start to track a target there. This is needed because the mount drifts on the vertical axis and we need to get this vertical (Alt) component during tracking for the SoftPEC.
5. Run an alignment on the Alignment tab with Capture & Solve. The first dRA and dDE will be quite high.
6. Wait until the mount syncs and goes back to the original target. Select Nothing for Solver Action and run a Capture & Solve again immediately. The dRA and dDE values should be minimal (a few arcsecs).
7. Wait 5 or 10 minutes and run a Capture & Solve again. Inspect the dRA and dDE values. dRA should be quite minimal, but dDE will be _negative_ and several arcmins (<= -5 arcmin). Get the absolute value of dDE, convert to degrees and divide by the minutes how much you waited to run "Capture & Solve" . For example, if you waited 5 minutes and dDE was -03' arcmin: |-3'|=3' -> 0.05°, 0.05° / 5 min => SoftPEC Value = 0.01.
8. Just set your custom SoftPEC Value in the mount driver configuration page, enable SoftPEC and test it. It can be finetuned if it was a bit over- or underestimated.
Driver Name
Skywatcher Alt-Az Mount
Driver Executable
indi_skywatcherAltAzMount
Family
Telescopes
Manufacturer
Skywatcher
Platforms
Linux, BSD, OSX
Author
Roger James, Csaba Kertesz etc.
Version
0.1
