C11 & CGE PRO

The C11 is our second largest telescope and suitable for mobile use. Every time one likes to use it, one has to put it up again from scratch. The purpose of this article is to describe the details of this process.

To protect the sensitive electronics from humidity and other harsh weather conditions they are stored in the lab course room. The remaining mechanical parts stay in the dome, so that one does not need to carry them around.

1. the tripod
2. the tube (C11)
3. counterweights + bar

1. the CGE PROs electronic box
2. the CGE PRO mount
3. a box containing all 1.4″ eyepieces and the corresponding filters
4. sun filters

1. The CGE PRO uses a parallactic mount, which has to be adjusted to point to the northern celestial pole. Therefore, the tripod (see figure 1) should be positioned accordingly. To do so, it is usually sufficient to point the tripod leg with the carrier for the hand terminal to the south.
2. Now put the electronic box on the tripod (see figure 2) and fix it with three bolts (see figure 3).
3. For the next step place the mechanics of the CGE PRO mount (see figure 4) on the electronic box and again fix it with three bolts (see figure 5). Due to the heavy weight of the mechanics, this step should be performed by two people.
4. Screw the counterweight bar into the mechanics and place the counterweights on it (see figure 6). When you fasten the screws on them, they are hold in place.
5. Connect the electronic box to the engines of the mount. The cables <see imgref cables> go in the ports on the side of the electronic box figure 8 and have different length. The short one connects to the axis controlling the rec-ascension, while the longer one is for the declination (see figure 9). The cable only fit in one position.
6. Now plug in the energy supply (see figure 10) and the terminal (see figure 11) into the corresponding ports (see figure 12).
7. The attachment of the tube should be performed by two people, too. One inserts the dovetail into the clamp of the mount (see figure 13 and figure 14) and holds it in place. The other tightens the screws (see figure 15).
8. Remove the cover from the tube (figure 16) and add, if needed, the sun filter (see figure 17).
9. Now you can attach an eyepiece, a camera, or a spectrograph to the tube. To use 2″ oculars or one of the other instruments you need to exchange the 1.4″ adapter at the end of the tube by a 2″ adapter from the storage container.
10. Often a focal reducer is already attached to the telescope. It can be easily removed, if you don't want to use it.
11. Before using the telescope you have to tare the rotation axes. First lose the bolts fixing the right ascension axis, until you can freely move the telescope around this axis. Now adjust the position of the counterweights such that there is no movement along this axis anymore. Tighten the bolts again and repeat this procedure for the declination axis. As there are now counterweights now, shift the tube along the clamp to tare the declination axis. Again this should be done by two people.
12. Done! ( figure 18)

The CGE PRO can simply switched on and off via the On/Off switch at the electronic box. In contrast to the OST, the CGE PRO does not require any shutdown procedure. It simply can be switched off. After the boot of the mount, it is almost always required to perform an alignment. The following possibilities exist:

• Two Star Align
• One Star Align
• Solar System Align
• Quick-Align
• Last Alignment
• Re-Alignment

Unfortunately, the handling of the hand terminal of the CGE PRO is not as intuitive as the one of the OST. However, after a short settling in period also an inexperienced user can safely handle this mount.

Usually it is required to create a new alignment after each setup of the mount. If one wants to use more than one night in a row, there is the opportunity to put the mount into a hibernation mode (see below) that allow to disconnect the mount from the power supply and at the same time to conserve the alignment. If the mount is used at a fixed position, one also can make use of a saved alignment.

General procedure:

1. switch on the mount
2. press ENTERto start the alignment procedure
3. press ENTER to allow the mount to move to the initial position (the co-called switch position)
4. enter the date
5. enter the time
6. select Daylight Savings time or Standard time
7. select the time zone (+1)
8. select the alignment method

In addition to the above settings one also has to set the location after a reset of the mount to the default settings. This can be done by selecting a location from a list of known locations or by entering the latitude and the longitude.

The Solar System Alignment is useful especially for solar observations, since one can use directly to perform the alignment. While the precision of the Solar System Alignment is lower than what one can achieve with an alignment procedure that is based on several stars, it is usually sufficient for our purposes. Before the the can be used as an alignment star, it is required to allow the telescope to actually move to the sun, since this in blocked by default for security reasons. this can be done via UTILITIES → SUN MENU → ENTER. Apart from the points mentioned above, the Solar System Alignment requires the following steps:

1. select Solar System Align (with the ↑ and ↓ buttons and not with the NSWO buttons)
2. select Sun in the menu and confirm it with ENTER ⇒ subsequently the telescope is moving the estimated position of the Sun
3. search for the Sun and center the Sun in the eyepiece (Do not use the finderscope as suggested by the software, since we do not have a solar filter for the finderscope!)
4. confirm with ENTER
5. press ALIGN ⇒ Finished!

The Two-Star Alignment and it refinement with additional stars is the default procedure to build a new alignment for night observations. Besides the points mentioned above the following steps are necessary:

1. select Two Star Align from the menu → subsequently, the telescope suggests bright stars, which are above the horizon
2. select and confirm the first calibration star with ENTER
3. center the star in the eyepiece (the finderscope is often not very helpful, since it is most of the time not well aligned with tube)
4. confirm with ENTER
5. press ALIGN → afterwards the telescope suggests the second alignment star
6. center also this star in the eyepiece (in case it is not possible to find the star, one can select a new stat by pressing UNDO)
7. confirm with ENTER
8. press ALIGN → subsequently, the alignment can be improved with additional stars (3 are recommended, 6 are possible)
9. press UNDO to complement alignment

The hibernation modus offers the possibility to use the telescope several nights in a row, while switching off the power supply during the day. The hibernation procedure ensures that the alignment will be conserved. However during hibernation, it is not allowed to move the telescope at all. The following steps are necessary to put the telescope into hibernation:

1. press the MENU button
2. select HILBERNATE from the UTILITES menu
3. move the telescope to the desired park position
4. switch off the telescope
5. disconnect the power supply and arrange for weatherproof cover (Important: do not move the telescope anymore!)

Wake up:

1. reconnect the power supply
2. switch on the telescope
3. confirm Wake up with ENTER
4. confirm the time and the location
5. The telescope is ready for the next observation!

Known error sources and their solutions can be found here.

More details on the CGE PRO and the C11 can be found in the corresponding manuals in the lab course room.