KPO

Observatory
KPO Home
Control
The most important control device is the telescope drive. This has its own page .

The method of computer control has changed gradually over time. During the 90s it was using a custom bus and various control cards (in the picture below) using SSI technology. It is nearly all Modbus over ethernet now using subsystems based around the AVR microcontroller.

The control rack.
The new server is in the top "shelf" (we were changing over the servers when this was taken and old server is the computer on the floor). The ethernet switch and patch panel is a bit lower down.

Control boards from last century. :-)

Most recemt controller for the dome.

We used to keep time using an HP105B oven-stabilised quartz frequency standard. A redicuously expensive piece of equipment which we acquired from a decomissioned observatory. Now we just use a GPS clock, in particular, this one. This is used to discipline the clock in our Linux server using ntp. It can be seen (sort of) on the pole in picture to the left. The other thing visible is our rain gauge.

Display for GPS clock.
The box underneath is our video server .
To see the time on a normal(ish) clock we started off with a sidereal clock from  AWR  which normally runs off its own quartz crystal. This was modified by chucking out the main control board and making a new one to control the LCD. While this is a strange way to build a clock it was convenient as we already had the clock (we didn't buy it for the purpose of rebuilding it). The new board is basically just a micro with a serial port. It receives time information  from the GPS clock and displays it on the LCD, synchronised with the 1Hz reference pulse. The new version also shows sidereal time just like the original clock using the GPS longitude and a pile of maths to figure out the time.