Watcher has been primarily designed to study the optical afterglow of gamma-ray bursts. The hardware components were very carefully chosen to build a telescope suitable for this task. As the most important goal is to image the afterglow as quickly as possible, the result is a medium sized mirror on a fast mount with a very efficient CCD.



Watcher uses a 16″ Classical Cassegrain optical tube assembly provided by Optical Guidance Systems. The assembly features a 16″ parabolic primary mirror and a 4.25″ hyperbolic secondary mirror. Automatic focus adjustments are achieved using a Robofocus system attached to the secondary mirror.


The Andor iXon+ 888 CCD uses an E2V back-illuminated sensor. This sensor has 1024×1024 pixels with the best efficiency available. Over 90% of photons are detected by this sensor. The Andor CCD also features electron multiplying technology which allows us to read out images incredibly quickly without increasing readout noise. This is crucial in the first minutes of a GRB as it greatly reduces the amount of time that the telescope is waiting to take the next image.


Watcher’s filter wheel can accommodate 8 filters. It is currently configured with: clear, V, R, g’, r’, i’, H-alpha, and OIII filters supplied by Astrodon. The filter wheel moves quickly enough that almost all filter changes can occur while the previous image is being read from the CCD. This allows us to take images with various filters without sacrificing any extra time.


Watcher uses a Paramount ME equatorial mount. This mount is one of the most capable off-the-shelf systems available and is able to move Watcher’s relatively heavy optical tube into position quite quickly. The equatorial geometry of the mount provides good tracking ability for longer exposure images.


A robotic telescope is a complex instrument and there are many more components than those listed above. For a complete overview of Watcher’s components, and how they fit together, see the Watcher block diagram.

For more detailed hardware information please see the Watcher Hardware Guide.