The BAO Telescope control system.


The BAO Telescope Control System is designed to integrate the control of all the main observing instruments at BAO. This includes the main telescope's stepper drive system and the operation of the science CCD camera and the guide camera.

The TCS was planned already in 1989, when Bjarne Lassen joined BAO. With his great interest in electronics in general and stepper motors in particular, he was the master mind behind the project. But the project was delayed again and again due to lack of time. The TCS was installed and ready for operation in the spring of 1993.


The two stepper motors (4 phased) are attached directly to the worms of the drive. They are driven by two custommade controller cards, placed in a 19" card cage. On the picture below, you can see the card cage on the floor, surrounded by the rest of the equipment. This picture was taken in connection with the final tests in BAO Hardware Divisions test lab. A 80286 PC is driving the steppercontrollers by sending pulsetrains to them via two 8255 I/O cards. This job is highly time critical, so the software on this PC has to be designed carefully with respect to execution time.

The 80286 PC is talking to the PC in master control of the whole TCS via an RS-232 line operating at 115200 baud. At given intervals, the TCS PC is receiving information about the step counters values and sending commands to move the telescope to a new position.


This is the observatory main computer. From this you can control the TCS , science CCD camera and the CCD autoguider. The software is designed in a sort of "multitasking" way, that is, slewing with the telescope and making image reductions can be done at the same time. You can also start a longtime exposure with the science camera, and meanwhile flatfied a previously taken image. The TCS software also has features like automatically calculating the polar misalignment, removing backlash in the gears and user-defined setting of both slewing, setting and guidespeed.
This is what observing was like before we got the new TCS and electricity.
This page is maintained by Jacob Clasen
and Søren Larsen
Last updated: May 15th, 1995.

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