THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT 2003-2004

4. New Instrumentation: WFCAM (1-2.5µm camera with four 2048x2048 arrays)

The ramp up for delivery of WFCAM to the JAC in 2004 was a busy time for both ATC Edinburgh and JAC Hawaii staff.

In early 2003 the filter arms and focus mechanisms were manufactured and tested. The window, field flattening lens and field lens were delivered to the ATC. Most filters were delivered and the Z filter ordered. Thermal performance of the cryostat was verified. The remaining two science grade detectors were delivered in July 2003. Software testing of filters, focus, and four camera systems was completed. Hardware for data acquistion and reduction was delivered. Work continued on the proper mounting and cooling procedures for the engineering grade arrays. At the JAC, the telescope mirror plug and covers were modified during the June-July realuminising shutdown.

In late 2003 the Z filter was delivered. The array co-planarity method was implemented. The tertiary and secondary were delivered and the tertiary tested at instrument temperature and for flexure. There was a successful autoguider subsystem test at the JAC.

During 2004 WFCAM preparations continued at the JAC: handling tools and storage items were procured and installation of the cryostat on the telescope was practised using a WFCAM mock-up. The ATC continued to check the mechanical and thermal stresses on the detectors, and constraints on the uniformity of cooling led to improved mounting methods for the detectors. After considerable manufacturing delays, the corrector plate was delivered to the ATC but was found to not meet specification. The errors were corrected and a re-polished plate delivered to the JAC in September 2004 in time for on-sky commissioning.

In September 2004 WFCAM arrived at the summit. During the secondary mirror alignment it was found that two of the three flexures which mount the mirror to the hexapod were broken. The connection was rebonded and commissioning continued. WFCAM first light was on 21st October 2004. A detailed set of measurements showed that the instrument would have to be opened up and some realignment of the optics performed in early 2005. Despite the somewhat compromised image quality, WFCAM performed well, with throughput measured to be better than UFTI's. Test data were taken on a sample of the UKIDSS survey fields so that operational modes could be determined and the pipeline tested. The pipeline and archive work is being done at Cambridge and Edinburgh, respectively, and is proceeding well. A set of data reduction recipes now exist in ORACDR and a prototype server exists for the WFCAM science archive. More information on the commissioning, the pipeline and the archive are given in the Spring 2005 UKIRT Newsletter . WFCAM was removed from the telescope in early December for engineering prior to being reinstalled in March 2005.

Figure 10: Commissioning observations of the Great Nebula in Orion, illustrating WFCAM's ability to image detail on large and small scales simultaneously. The left-hand image shows a full WFCAM tile; the image at right shows the many features seen only in the near-IR in the dark cloud to the north of OMC-1 and the Trapezium cluster. The small green square bottom-left shows the UIST field-of-view. Data courtesy of Chris Davis & Watson Varricatt. Final colour composite produced by Douglas Pierce-Price.