Several values can be entered on the Setup window for the ASCOM ServoCAT driver. These values include:
- Serial Port (Required)
- Observing Site Location (Longitude strongly recommended)
- Mount Type (strongly recommended)
- Telescope Optics (Recommended)
A proper serial port setting is required to establish communication between this ASCOM driver and the ServoCAT hardware.
By selecting the proper mount type (Alt/Az, Equatorial, or German Equatorial) the driver will be able to report your correct mount type if the planetarium software asks for this information.
The ServoCAT ASCOM driver uses your site longitude when planetarium software asks the driver for Sidereal time. The site longitude you specify on the driver setup screen is used along with your computer's time to calculate Sidereal time. Sidereal time is neither read from nor written to the ServoCAT or ArgoNavis. Likewise, site location values you enter here are not read from nor written to the ServoCAT or ArgoNavis.
Sidereal time should match the Right Ascension of an object that is on your meridian (due south). If you find that your planetarium software is using an incorrect value for Sidereal time, and you have already set the proper site location in your planetarium software, it is possible that the planetarium software is ignoring its settings, and trying to get the value from the ServoCAT ASCOM driver. If this is the case, then you need to make sure that the proper site longitude is set on the driver setup screen, and you should also double check that your computer's time and time zone settings are correct.
If your longitude is West (true for North America), be sure to indicate 'W' on the driver setup screen. When the setup screen is saved, you will see a message window indicating your current Sidereal time based upon your computer time and the longitude that you entered. If you are seeing strange behavior from your planetarium software, you should double check the reported Sidereal time. If you do not wish to see your Sidereal time displayed in a message window when you exit the setup screen, you can turn off this feature by un-selecting this feature's checkbox.
With the exception of Serial Port and Site Longitude, all other parameters on the setup screen are optional. These values can be reported to the your planetarium software, and can be reset by your planetarium software. It is up to your planetarium software to use these parameters.
If you enter Aperture Diameter and leave Aperture Area at zero, Aperture Area will be calculated from the Diameter you supplied. The ASCOM Telescope v2 Specification defines Aperture Area as the area of the telescope's aperture, taking into account any obstructions. If you wish to be to the letter of the spec, you will want to subtract the area of any central obstruction.
Although the ArgoNavis can be configured to do refraction corrections, this has no effect on the RA or Dec values received or sent. For this reason, this setting is no longer part of the ServoCAT ASCOM driver parameters.
Please see ServoCAT ReadMe.htm for more details about the ASCOM ServoCAT Driver, including a discussion of coordinate reference systems and refraction correction.
Thanks for trying this driver, I hope it helps you go to many wonderful objects!
This ServoCAT Driver.htm file was last updated August 2011.
Peter Eschman, eschman@unm.edu