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Spanish Telescope Commissioning

Observatory Sciences consultants worked in Spain in September 2014 for the commissioning of a Spanish 2.5 metre telescope control system. We are pleased to report that the control system worked first time, enabling rigorous testing of the pointing performance.

The Javalambre Survey Telescope (JST/T250) was built by AMOS in Belgium for the OAJ (Observatorio Astrofisico de Javalambre) based in Teruel, Spain. Together with its smaller sister T80 telescope, the T250 will provide Spain with state of the art facilities for wide area astrophysical surveys.

On 25 September 2014, at 22:57 local time, the T250 achieved engineering first light. This important milestone in the project was the first time that photons, in this case coming from the star Polaris, went through the complete optical system of the telescope. The telescope control system developed by Observatory Sciences co-ordinates several sub-systems, including the secondary mirror hexapod motion control, the telescope dome, the guiding system and a wavefront sensor system used to monitor and improve the image quality.

The guiding system incorporates four charge coupled devices (CCDs) at the corners of the telescope field of view which will be used to monitor the position of guide stars. The guiding and active optics systems for the T250 telescope have yet to be commissioned.

Observatory Sciences developed the telescope control system using the TCSpk software package provided by Tpoint Software (Pat Wallace). The interactive software tool TPOINT was used during commissioning, an analysis tool that takes telescope pointing observations and determines a mathematical model to describe the various systematic errors in the telescope and mount. With the TPOINT model embedded in the actual control system code, target acquisition is swift and assured, and long-term tracking accuracy enhanced.

The improvements come about not only through the continuous correction of mechanical errors such as misalignments and flexures, but also as a result of accurate mount alignment. The TPOINT analysis tool has been widely adopted by both professional and amateur astronomers on telescopes of many different designs, including equatorial and altazimuth mounts and optical, IR and radio telescopes.

Observatory Sciences consultant Philip Taylor comments: “TCSpk and TPOINT use the same accurate and sophisticated algorithms for both controlling and analysing pointing and tracking, so it’s no surprise that it has become a standard worldwide for telescope control systems. Observatory Sciences has extensive expertise with this software, following a licencing agreement signed with Tpoint Software in 2008, so we were confident during T250 commissioning that our software would work as expected.”

Software for Astronomy and Physics Projects