The South African Astronomical Observatory (SAAO), the National Research Foundation (NRF) and their international partners on Monday relaunched the Southern African Large Telescope (Salt) in Sutherland, six years after it was first launched in November 2005.

Speaking to Engineering News Online, SAAO director Professor Patricia Whitelock and Rutgers University Professor Ted Williams, who chairs the Salt board, explained that some major problems had to be overcome to bring the telescope to its full capability, leading to the relaunch of the facility.

The first prominent issue had been with the spherical aberration corrector, which had resulted in collection of blurred images, presenting severe problems for the astronomers. “You can only do poor quality science with poor quality images,” said Whitelock.

While it was initially thought it was the design of the four-element mirror within the spherical aberration corrector that was problematic, it was however found that “the design was perfect but the mechanical structure was not. The four mirrors were in a structure that was flexing slightly.” Whitelock said that a redesign of the mechanical structure to be stronger and stiffer was able to remedy the issue in September 2010, giving the clear images required.

The second issue had been with the Robert Stobie Spectrograph, which according to Williams was the “real workhorse” instrument of the telescope. It allowed Salt to work further into the ultra-violet part of the spectrum than any other large telescope in the world. “It’s one of the things that makes Salt unique,” said Williams. “Unfortunately, when we started using it we found that what was meant to be one of the world’s best instruments in the ultraviolet was in fact one of the world’s worst.”

Williams explained that it took approximately one-and-a-half years to track down the problem, which was found to be a chemical incompatibility between two of the components in the instrument, rendering the spectrograph incapable of viewing in the ultraviolet range of the spectrum. After a year of investigating the chemistry of the components at the University of Wisconsin in the US, the spectrograph was reconstituted and after a full year’s additional testing at the Salt facility was placed back onto the telescope in April 2011.

Speaking to the audience at the inauguration, Whitelock said that while the event was being billed as a re-inauguration, it should be considered as the start of Salt science operations. “And Salt science operations haven’t started discontinuously; they’ve been gradually ramping up as less engineering is necessary and more science is possible.”

NRF CEO Dr Albert van Jaarsveld explained that the relaunch was a reaffirmation of the international partnership that has been working on the Salt project since its inception. “This international partnership has brought it to this point, but we need to make sure that it remains competitive and we have to keep investing and growing capabilities. The partnership needs to take stock, and this was that opportunity.”

Astronomers can apply every six months for time on the Salt telescope and according to Whitelock the first “serious” session with all the instruments and the telescope in full operation began on September 1 of this year. All the international partners in the project are allocated time, the extent of which depends on their interest in the telescope, with South Africa’s allocation being one-third. Whitelock and Van Jaarsveld said that the interest from local researchers had been significant, with applications for the South African portion of the time in the last bid round being oversubscribed by 3.6 times.