6.When the download is complete, the Firmware Loader will display “Update Complete”.
The firmware in the computerized GoTo hand controller has now been updated.You can click on the “HC Version” button to confirm the new version number of the firmware (and possibly the database, but the hardware version will not change with internet updates).
Note: If the error message “Can not connect to a SynScan hand control” appears on your computer, check all cable connections. Also, try closing all other computer pro- grams that might be attempting to use the COM port.
Note: If the error message “Firmware update failed...” appears on your computer, remove the power plug from the hand controller, and then reconnect it. Now, repeat the firmware update procedure.
By default, the data communication rate between the GoTo hand controller and the computer is 115kbps. The RS-232 port on some PCs may not support this high data transfer rate. If the firmware update procedure fails after a few tries, try reducing the data transfer rate by pressing the SETUP but- ton on the hand controller. This will reduce the data transfer rate to 9.6kbps. The controller’s LCD screen will show “Lo” in the lower right hand corner to indicate the lower transfer rate setting. The firmware update procedure remains the same except it will take much longer for the firmware to load into the hand controller.
8. Collimating the Optical System
To get the sharpest images, your telescope’s optical sys- tem must be in precise alignment. The process of aligning the primary and secondary mirrors with each other and with the mechanical axis of the telescope is called collimating. Collimating is relatively easy to do and can be done in day- light or at night.
Because the primary mirror is shipped separately from the optical tube, the telescope’s optics must be collimated before it can be used. Most of the adjustments will be to the tilt of the primary mirror, as the secondary mirror has been pre-aligned at the factory. It is also good idea to check the collimation (optical alignment) of your telescope before each observing session and make any necessary adjustments.
To check collimation, remove the eyepiece and look down the focuser drawtube. You should see the secondary mirror cen- tered in the drawtube, as well as the reflection of the primary mirror centered in the secondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror, as depicted in Figure 25a. If anything is off-center, as in Figure 25b, proceed with the following col- limation procedure.
The Collimation Cap and Mirror Center Mark
Your XTg comes with a collimation cap. This is a simple cap that fits on the focuser drawtube like a dust cap, but has a hole in the center and a reflective inner surface. The cap helps cen- ter your eye so that collimating is easier to perform. Figures 25b-eassume you have the collimation cap in place.
As an additional aid in collimating, the primary mirror of the XTg has a tiny adhesive ring marking its exact center. This center ring will not affect the images you see when observ- ing with the telescope in any way (since it lies directly in the shadow of the secondary mirror), but it will greatly facilitate collimating when using the supplied collimation cap or other, more sophisticated collimation devices, such as the Orion LaserMate Laser Collimator.
Preparing the Telescope for Collimating
Once you get the hang of collimating, you will be able to do it quickly even in the dark. For now, it is best to collimate in day- light, preferably in a brightly lit room and aimed at a white wall. It is recommended that the telescope tube be oriented hori- zontally. This will prevent any parts from the secondary mirror from falling down onto the primary mirror and causing damage if something comes loose when you are making adjustments. Place a sheet of white paper inside the optical tube directly opposite the focuser. This will provide a bright “background” when viewing into the focuser. When properly set up for col- limation, your telescope should resemble Figure 26.
Aligning the Secondary Mirror
With the collimation cap in place, look through the hole in the cap at the secondary (diagonal) mirror. Ignore the reflections for the time being. The secondary mirror itself should be cen- tered in the focuser drawtube. If it isn’t, as in Figure 21b, its position must be adjusted. This positional adjustment of the secondary mirror will rarely, if ever, need to be done.
To adjust the secondary mirror left-to-right in the focuser draw- tube, use the included 2mm hex key to loosen the three small alignment setscrews in the center hub of the 4-vaned spider several turns. Now, grasp the mirror to prevent it from rotating (be careful not to touch the surface of the mirror), while turn- ing the center screw with a Phillips head screwdriver (Figure 27). Turning the screw clockwise will move the secondary mir- ror toward the front opening of the optical tube, while turning the screw counter-clockwise will move the secondary mirror toward the primary mirror. When the secondary mirror is cen- tered left-to-right in the focuser drawtube, rotate the second- ary mirror holder until the reflection of the primary mirror is as centered in the secondary mirror as possible. It may not be perfectly centered, but that is OK for now. Tighten the three small alignment setscrews equally to secure the secondary mirror in that position.
Note: When making these adjustments, be careful not to stress the spider vanes or they may bend.
The secondary mirror should now be centered in the focuser drawtube. Now we will shift our attention to the reflections within the secondary mirror in order to properly adjust the tilt of the secondary mirror. Adjusting the tilt of the secondary
