From: Marc BalcellsSent: martes, 11 de marzo de 2014 13:34 To: ingnews@ing.iac.es Subject: [INGNEWS] WHT oscillations problem solved INGNEWS WHT OSCILLATIONS PROBLEM SOLVED Over the years, oscillations in azimuth and elevation have occasionally been seen at the WHT, but these have been rare and short-lived, and have had little impact on observing. In December 2013 oscillations in azimuth suddenly began to occur more frequently. By early 2014, ~ 3% of the observing time at the WHT was being lost due to oscillations. This was a source of considerable frustration for affected observers. Tracing the origin of the oscillations, which could not be reproduced during the day, proved surprisingly difficult, and required a thorough review of the mechanical, electronics and software components involved. A breakthrough came on 25 February when an ING electronics engineer identified a failing capacitor in the azimuth power amplifier. After replacing the degraded capacitor, the azimuth oscillations have not been seen again. ING continues to monitor closely the tracking performance of the WHT, but we are reasonably confident that the oscillations problem has been solved. We would like to thank observers for their patience when faced with the loss of telescope time. For their role in resolving this stubborn problem, we congratulate the staff of ING's telescope and instrument group, the staff of the ING operations team, and Martin Fisher (ex-ING), who helped our team analyse the diagnostic data. Marc Balcells Director ING ---------------------------------------------------- Dr. Marc Balcells, Director Isaac Newton Group of Telescopes 38700 Santa Cruz de La Palma, Canary Islands, Spain Tel. +34 922 425 403 http://www.ing.iac.es balcells 'at' ing.iac.es