Telescope and Dome

The Joan Oró Telescope (TJO), manufactured by OMI, has a 0.8-m primary mirror with an overall F/9.6 optical system in  Ritchey-Chrétien configuration. The telescope has an equatorial fork mount capable to point, in less than 30 seconds (including dome), anywhere above 5 degrees from the horizon.

The TJO has a pointing accuracy better than one arcmin for most positions, with worse performance at low elevations and large hour angles. The TJO has no guiding, but tracking is stable within one arcsec for exposures up to 5 minutes, reaching 10 minutes near the meridian. An autoguiding system is active when using the ARES spectrograph, allowing to execute longer exposure times (maximum of 30 min recommended to avoid effects of cosmic rays).

The instrumentation is placed at the Ritchey-Chrétien focus. A segmented cover protects the primary mirror from dust when the telescope is stowed. All these elements are automatically controlled.

The basic equipment supplied by the telescope manufacturer included the TALON software, built on C and shell scripts to be run on Linux. TALON, now freely distributed under the GNU license, enables the control of different elements to automatically acquire astronomical observations. The hardware elements controlled by TALON at the TJO are the following: telescope, dome and MEIA.

The electronics used to handle all the movements of each telescope component (Hour Angle and Declination axes, mirror covers and focus), the filter wheel and the dome include the Clear Sky Institute Motion Controller (CSIMC) boards, distributed by OMI.


The TJO is covered by a 6.15-m classical dome manufactured by Baader Planetarium GmbH. The sky view for the telescope is enabled through a shutter and a flap, providing an opening of 97 x 29 square degrees. The opening and closing of the dome, and the movement in azimuth, are nominally controlled from the host computer using the TALON software. The communication between the CSIMC board and the dome electronics is based on the TTL protocol.

The robustness of the dome aperture control is a must to ensure the robotic operation and represents the most critical single point of failure at the TJO. The dome aperture can be independently controlled by a redundant control system, providing a highly reliable response to any unforeseen alarm and in case that the nominal control failed.

Generalitat de CatalunyaUniversitat de BarcelonaUniversitat Autònoma de BarcelonaUniversitat Politècnica de CatalunyaConsejo Superior de Investigaciones CientíficasCentres de Recerca de Catalunya