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Handle large instruments at will: development of instrument-handling cart

For observations, we have to attach observation instruments to the TAO telescope. The TAO telescope has four places where instruments can be mounted (called foci): two bent-Cassegrain foci and two Nasmyth foci (Fig. 1). Relatively small instruments will be mounted on the bent-Cassegrain foci, and the mainstay instruments, SWIMS and MIMIZUKU, will be mounted on the Nasmyth foci.

Fig. 1. Nasmyth focus and bent-Cassegrain focus of the TAO telescope. Each focus is also located on the opposite side.

These mainstay instruments are large, measuring approximately 2 meters on each side and weighing up to 2.6 tons, making them difficult to handle. To handle such large instruments safely, we developed three carts; moving cart, rotating cart, and mounting cart.

Cart NamePurpose
Moving CartMove the instrument safely
Rotating CartRotate the instrument by 90 degrees
Mounting CartMount the instrument to the telescope focus
Table 1. Three carts and their purposes

The moving cart transports an instrument on it between the operation building, where instrument maintenance is performed, and the enclosure building, where the observation operations are conducted (Fig. 2.). The observation instrument is loaded on the pedestals located at the four corners of the top of the cart. The cart has wheels at the four corners of the lower part and provides smooth transportation by running on the rails laid between the operation building and the enclosure building.

Fig.2. Moving cart for observation instruments

If we say that the attitude of the instruments, SWIMS and MIMIZUKU, when mounted on the moving cart is vertical, the attitude when mounted on the telescope is horizontal, rotated by 90 degrees. Therefore, these large instruments must be safely rotated by 90 degrees before installation. The rotating cart enables this rotation safely. Figure 3 shows the rotating cart in the process of rotating a dummy instrument that simulates the weight and size of an instrument (approximately 45 degrees rotated). The attitude of instruments is changed from vertical to horizontal and vice versa by such operations. This operation is conducted at the floor around the telescope, and the instrument in the horizontal attitude is craned and put on the mounting cart for mounting to the telescope (Fig. 4.).

Fig. 3. Rotating cart in the process of rotating the dummy instrument (black cube structure)

The mounting cart works on the Nasmyth platform (see Fig. 1., fenced area in front of the Nasmyth focus). Figure 4 (left) shows the mounting cart put on the Nasmyth platform in front of the Nasmyth focus. The instrument in the horizontal attitude is loaded on the triangular frame at the top of the cart. This triangular frame can be driven horizontally by three linear actuators, and the entire cart can be driven vertically by three linear jacks. This enables six-axis control of the attitude of the instrument and facilitates safe installation of it by aligning the orientation and position of the instrument with the Nasmyth focus.

Fig. 4. (left) Mounting cart in front of the Nasmyth focus
(right) Dummy instrument mounted on the Nasmyth focus by the mounting cart

Development of these three carts was completed in Japan, and they were shipped to Chile in August 2021 (Fig. 5.). They safely arrived in Chile in November 2021 and are currently in a local warehouse awaiting their turn.

Fig. 5. Mounting cart loaded onto a truck for transport to Chile