Maintenance of biggest telescope in Sri Lanka the 45cm GOTO telescope

The primary mirror of the 45 cm GOTO telescope was cleaned for the first time in 2000 under the supervision of the Japanese astronomer who visited ACCIMT as an JICA expert. Ever since the primary mirror has not been cleaned and we decided to wash the mirror in January 2006. Before remove the mirror we had to get the necessary tools used for clamping the telescope and removing the main mirror ready. As some of these tools have been rusted we repainted them, including the hydraulic stand used to lift the mirror cell. Having prepared all the tools we clamped the telescope and removed the primary mirror according to the instruction given in the maintenance manual. We noticed that about 20% of the mirror surface coated with 99.9% pure Aluminum has oxidized. There were a lot of dusts particles deposited on the mirror surface. First we blew off the dust using an electric blower. Then we gently poured distilled water on the surface of the mirror and removed dust particles as much as possible. To remove stains on the mirror we used PH 5.5 facial wash solution. By applying little amount of ph 5.5 facial wash on the mirror we rubbed the mirror gently in the radial direction. We were able to remove all most all the dust and stains on the mirror successfully.

There is a smart mechanism on the primary mirror holder to align the primary mirror with the optical axis of the telescope. We dismantled the mirror holder and studied the alignment mechanism thoroughly. This is necessary as we must perform the optical alignment after placing the mirror in the telescope.

We have also noticed that the one of the telescope driving assembly had an unusual noise and we wanted to check it. We dismantled the driving unit and found that the tolerance between the gears were too much. We adjusted the gear wheels to reduce the gap in between gear wheels.

Finally we reassembled the telescope mirror and its driving system successfully.

Recently GOTO Telescope has been down as its power and control wire buses had been destroyed by rats. Wiring system of the telescope was studied by the staff and was replaced the damaged wire bus system with new wires. Measures were taken to prevent further such damages by protecting the wires with Galvanized flexible conduits and sealing the wire buses with metal plates. Telescope controlling system was recovered.