Progress on the WFCAM Instrument at the UKATC

Mark Casali & the WFCAM Project Team

After years of calculation, design and reviews, WFCAM is now leaping off paper and into aluminium. Progress over the last six months has been rapid and the large team is moving all sub-assemblies forward in parallel toward a system integration phase beginning in the summer - a critical time when unexpected problems and delays may show themselves. An important theme in our risk mitigation plan has been to work closely with manufacturers after issuing of contracts, so that we become aware of problems and delays early on and can work with them to recover lost time. This approach has already saved the project from major slippages due to manufacturing delays and technical problems.

Other groups are involved in major work packages for WFCAM. CASU at the IoA in Cambridge are developing the full data reduction UK pipeline as well as the summit pipeline necessary for data quality assurance. The WFAU at the IfA in Edinburgh are developing the science archive and user interface tools to query the large catalogues and image data. JAC in Hilo have taken on telescope-side software developments for WFCAM, the design of the new M1/WFCAM interface plug, and design and procurement of the WFCAM handling truck. SUBARU are procuring the remaining three Hawaii-2 detectors for us, as part of an agreement with PPARC.

Electronics and detectors

We have so far received only one of the four science grade Hawaii-2 devices ordered, along with several engineering devices and multiplexers. Rockwell are experiencing delays due to poorer than expected device yields. In the meantime we have carried out extensive tests of the one we have (#41). QE across science bands is good with mean values of 0.66, 0.68, 0.77, 0.76 at Y,J,H,K. Persistence, which has been something of a problem with the HgCdTe PACE process on saphire, is virtually unmeasurable. Read noise is better than spec and we achieve a 15-electrons CDS with a prototype preamp + controller lab system. Cosmetically the device is quite good with a single dead column in one of the quadrants and a roughly circular patch of a few hundred contiguous bad pixels. One unexpected problem discovered during focal plane prototyping was a mechanical instability in which the detector squirmed out of its ZIF socket by ~15 microns with each thermal cycle. With WFCAM's f/2.4 fast final focus we need excellent detector coplanarity and mechanical stability, so this has forced a late re-design of the focal-plane assembly.

All four 32-channel SDSU controllers have been received - a major electronics milestone. These required the development of new 8-channel analogue boards and 250 MHz fibre link, and the entire 128 channel system will be able to read out the four 2kx2k detectors in around 0.65 seconds. The controllers will be mounted under the mirror cell, with ATC-designed preamps on the cryostat.

FIGURE 1: The WFCAM cryostat in the lab.

Cryostat and mechanisms

The WFCAM cryostat was delivered just before Christmas, and vacuum tests were conducted in January 2003. Some re-seating and cleaning of o-ring seals was found necessary to remove leaks and the cryostat vacuum performance is now satisfactory. The radiation shield, internal optical tube and focal plane ring have also been delivered. We anticipate that the first cooldown, during which key internal temperatures will be checked, will occur towards the end of February. Optical alignment tests of the cryostat assembly will be done vertically, but flexure tests of the entire cryostat with field lens tower will be conducted horizontally.

A new stiffer primary mirror lifting plug, onto which WFCAM will mount, is being manufactured and will be shipped to JAC in time for mirror aluminizing in summer when it will replace UKIRT's original one.

FIGURE 2: The M2 mirror with lightweighting pockets visible. This will fit on the existing UKIRT tip-tilt/hexapod assembly.	FIGURE 3: The M3 Zerodur double-arch mirror. This will operate at around 120K.

The WFCAM filter paddles are a new type of cryomechanism and were prototyped and tested cold last year. Tests consisted of cold lifetime tests involving thousands of cycles inside a large test cryostat. Accuracy and repeatability has been shown to be excellent. The full 8 paddle set is now being manufactured.

FIGURE 4: The WFCAM handling rig on display at the suppliers

Optics

Manufacturing of all the optical components by SESO and AMOS is now well under way. The cryostat window and final field flattening lens are finished and awaiting coating. Rough machining of the other components including the new lightweighted secondary and double-arch zerodur tertiary is complete. Small imperfections (chips) arose from the machining process in the field lens, M2 and M3 optics. These have no impact on the performance of the field lens and M2, and have been removed by grinding in the case of M3. SESO has test-coated samples with their proposed broadband anti-reflection coating and have shown that our specification is achieved.

Software

The WFCam software is currently progressing in two major areas, the camera control system and the high level sequencing and control systems.The real-time software for the camera controller has reached a stable release, and is now frozen for a time to allow development of the interfaces to the control systems. The sequencing and control systems are currently running in simulation mode, and we hope to have tested these on the final hardware in the next few weeks. The next two months will also be the first all up tests of the mechanism control and other services in a cold cryostat, work which was completed last year. Also, the prototype survey component of the Observing Tool (OT) is currently being tested.

Instrument Handling

WFCAM will mount above the primary mirror, and so some special handling gear will be required to safely install the one tonne cryostat. A custom lift truck has been designed by Hyster and JAC personnel will attend acceptance tests in North Carolina at the end of February.

Delivery

Delivery to JAC is planned for before Christmas 2003, with commissioning on the telescope early in 2004.

For the very latest information on WFCAM, please visit the WFCAM web pages at the UK Astronomy Technology Centre in Edinburgh.

UIST commissioning in Autumn 2003

Suzanne Ramsay Howat¹, Stephen Todd¹, Sandy Leggett² and Chris Davis²

The new UKIRT Imaging Spectrometer achieved first light on the telescope on 24th September 2003. This major event signified the end of an intense period of installation and testing by engineers and scientists from the UK Astronomy Technology Centre (UK ATC) and the JAC. Weather, telescope and instrument cooperated to allow UIST to be tested in its three major modes (imaging, spectroscopy and integral field spectroscopy) during the first half-night of observations. A 20 night commissioning period followed, completed in December 2003, before 'shared risks' PATT observing with the instrument began.

FIGURE 1: JHK "true colour" image of the elephant trunks" in the Eagle nebula. Right - a wide-field L-band image of the same regions, revealing some of the reddest and most embedded sources in the region.

The commissioning offered a chance to test out in more detail the UIST observational modes: thermal and non-thermal imaging and spectroscopy, spectral and imaging polarimetry and 3-D spectroscopy with the integral field unit. Three-colour JHK and L images of the Eagle nebula obtained during the commissioning (Fig.1) shows the powerful combination of the UIST field (2' square) and spatial resolution (0.12arcsec pixels). The field of view of thermal imaging in particular offers significant gains over IRCAM.

FIGURE 2: Top - a wide-field UFTI image of the star forming region G25.65. Note the "Herbig-Haro-like" bow shocks centre-left in these data. Bottom - a UIST IFU "image" of the bow-shocks structure discovered in the UFTI data. The UIST image shows the 1-0S(1) emission, though images of this object were obtained simultaneously in other H2 lines, allowing for excitation analysis.

FIGURE 3: An IFU "map" of part of the planetary nebula NGC 7027. The greyscale shows H2 1-0S(1) emission, the contours Br gamma emission.	FIGURE 4: An L-band spectrum of NGC 1068 showing the strong absorption feature at 3.4um.

Exploration of the integral field mode was one of the highlights of commissioning. UIST's deployable IFU is a unique feature of the instrument. Spectra are obtained over a 3.3arcsec x 6arcsec area of the sky, with spatial resolution of 0.24arcsec x 0.48arcsec. A 3D cube of data is produced by the pipeline reduction software. Extremely high fidelity observations of the wavelength dependent morphology of astronomical objects can be obtained with an order of magnitude greater efficiency than slit scanning techniques. A molecular hydrogen (1-0 S(1)) image of newly discovered bow shocks in the high mass star forming region G25.65 is shown in Fig.2.

FIGURE 5: Mark Horita, Tim Chuter and Chris Davis install new optics (grisms, filters and slits) into the UIST wheel modules at UKIRT. Sandy Leggett - also involved in the engineering work - took the photo.

Once the initial checks of the IFU were carried out, experiments in mapping larger objects were undertaken. Three IFU positions are required to span the diameter of the planetary nebula NGC7027. Images in 1-0 S(1) line of H2 and in Brackett gamma (Fig.3) show the excited molecular gas located in complex filamentary structures beyond the ring of co-located ionised and molecular gas.

UIST functioned with an extremely low level of fault during the commissioning. As a result, data were obtained for twelve UIST service programmes, many of which were completed. The service observations ranged from JHKLM photometry of galaxies to HK spectroscopy of brown dwarf candidates and integral field spectroscopy of elliptical galaxies. One spectrum obtained, of the 3.4micron absorption featurs in NGC1068, is shown in Fig.4. This spectrum confirms that the spectral shape of this feature in NGC1068 is the same as for the Galactic ISM. The absence of a 3.0micron ice feature is also confirmed, thanks to the wide wavelength coverage with the 1024x1024 UIST array.

Full information on the UIST performance can be obtained from the instrument web pages ( /UKIRT/instruments/uist/uist.html). In comparison with predictions before delivery, the overall image quality and functionality are as expected, with the wide wavelength coverage a notable enhancement over CGS4. However, the raw sensitivity is lower than anticipated due to significantly reduced instrumental transmission. During a February 2003 engineering period, a modest improvement will be wrought by increasing the instrument aperture. However, UFTI is recommended for JHK imaging, unless the large field is required.

Other enhancements to UIST during the scheduled engineering time include the installation of a new IJ grism and a grism to provide a cross-dispersed mode for the HK bands. The IJ grism should cover a wavelength range of 0.8-1.4 micron with higher efficiency than the work-around which has been in use during the commissioning and shared risks observing. The HK cross-dispersed mode will cover a range from 1.4-2.4 micron with spectral resolution of about 1000 with the 0.5arcsec wide (4-pixel) slit. Additional narrowband imaging filters have also been installed.

PATT applicants may apply to use these new grisms for 03B. However, they should mention a backup option in their proposal, in case these new grisms prove to be unusable.

View from the Top

Thor Wold

As usual, it seems, many changes are happening at UKIRT and surrounding areas. Firstly, we have a new look in the UKIRT control room. Here are two archival photos of the changes through the years, the lower photo is of our new layout, with eight large flat-screen LCD monitors and a further panel which serves as both the second head for kiki, our data-acquisition machine, and the link for our Polycom. The LED displays did not show up in the photo, but believe me, they were up and running. Now, the telescope and kauwa (the observing prep and data reduction machine) are three-headed. With this came a new screen management system to learn. Nobody can say they are getting bored around here. The top photo, courtesy of John Davies, shows observer Simon Green with his feet up on the venerable Ann Arbor computer, circa 1985. Note the Hadfields rack to the right, which is in the same position as always, and so appears over just behind the unidentified reprobate in the bottom photo. UKIRT was just beginning to hire full-time operators around this time, but often the observer would also run things (or Simon was just using the chair?).

Then and Now... The UKIRT control room back in the mid-1980's (top), and a few weeks ago. (Golden Oldie from 1984, courtesy of John Davies, UKATC). Click on each image for the gorey details...

Down in University Park where the JAC offices are, the Smithsonian folks are busy building their new headquarters across the street. The US Department of Agriculture is erecting a new office and lab building at the corner where you turn towards the office complexes, and ground has been broken for the new $30 million Mauna Kea Astronomy Center, which will contain an exhibit gallery and world-class planetarium.

Construction on the first $60 million segment of the Saddle Road re-alignment is slated to finally begin this fall. This is 13 miles of the 47 mile project, and will move the current route through the military's Pohakuloa Training Area further up the side of Mauna Kea, so that traffic will no longer bisect the training grounds. This is Section II of the project. I was quite surprised to find out that the planners have changed their minds and decided that the next sections they will worked on will be Sections III and IV, which will cost $52 and $12 million, respectively. These are the sections that will run from the 6 to 28 mile markers, up from Hilo. The timetable for this is pending the securing of funding. Section I, which is the western end, will be last...so the personnel who are headquartered in Waimea will have to wait.

Section IV will connect to the 6 mile mark on Kaumana Drive, where construction of the Puainako Street extension is well underway. When this is completed, we will be able to traverse from the offices off of Komohana Street, up Puainako and right onto the realigned Saddle Road and on up to the summit. Not only will this be more convenient, it will be quite a bit safer.

As if construction down there were not enough, there is a lot to contend with up at Hale Pohaku. It seems that the folks that run our camp forgot that their main mission was to support people that work all night, so need to sleep in the day! They launched a project to bring the place into full compliance with the Americans With Disabilities Act; decided that the ramps that lead off the upper parking lot were substandard, so they cranked up the jackhammers nice and early, even removing the pavement from a few parking stalls while they were at it. Not satisfied with this, they also started into another project, replacing the siding on Building C, while still putting people in the rooms! They are still putting people in rooms only one room away from the activity to this date. The resulting impact on the lack of sleep on the JAC TSSs merited a stiff letter of complaint - if for no other reason than this was a safety issue. It really seems that they DID forget that people do need sleep! I have always thought it would behoove the folks that run the show to try to follow our sleep patterns a few times a year, to remind them. Also to stay in the rooms. Yeah, right...

One hopes this will be over and done with soon, but a noticeable lack of activity after the first few weeks of intense action is now happening. One benefit to come from this (whenever it finally happens!) is the enlargement of the upper parking lot. In the meantime, as of this writing, they are going to rip apart the toilets in the commons building, which will undoubtedly take some time. We will have a host of porta-potties located out the western door until whenever.

So, as for your wonderful Vacation Resort Hale Pohaku: so much changes...yet so much stays ever the same.

The tour vans that run up the mountain every day to catch the sunset are seemingly always totally full. I've heard that Mauna Kea is now classified as a major tourist attraction, and the number of folks wandering around at sunset is certainly an indication. The van drivers apparently have discovered the silversword plant I wrote about in the Autumn 2001 issue of the Newsletter. They park and disgorge the hordes, armed with their cameras, to hopefully not abuse the poor plant. I hope that at least this ensures that the fence around it to protect it from the feral ungulates will be maintained.

The Rangers who have been hired to monitor the visitors have been performing wonderfully. They keep people from knocking on our door, and I've not found anyone up on our roof for years! They also make sure people go down after sunset. Their hiring came just in time, with the huge increase in the tourists.

We have just begun our experiment in fully-flexed observing. I have had the pleasure of being the first TSS at the helm for the first run and it appears to be working very well. Stuart Littlefair, the observer whose program was rated highly and who then came out to run the queue did manage to finish almost all of his own program. We also started taking data for four other programs (depending on the atmospheric conditions) within these first five days allotted. Had his run been classically scheduled, he would have gotten one night's worth of data. Stuart was a joy to work with through this 'teething' process, keeping his good spirits up while we worked out the inevitable kinks.

Note to Stuart: take heart that the cooks at HP didn't zero in on you or I am sure they would have dug up some creative apellation with a twist on the movie mouse Stuart Little. You know how they give everyone pet names (no pun intended).

Greatly assisting in organizing and handling this is the OMP system, which has been discussed in this publication previously. It seems to be working well, but as always, it is still evolving as we see what our needs are in the realm of working in fully queued-scheduling.

This winter has been considerably less wet than last. A weak El Nino condition was declared last fall; it has already been declared to be weakening in January and the forecast is for 'normal' weather patterns (whatever that means!) to prevail April through October. The moisture that made its way to the upcountry last winter and spring and made the pastureland once again green has been long gone. So have the cattle, who have been moved to lower pastures. The upcountry drought in Hawai'i that has been going on for more than the past ten years continues. Even Hilo, notorious for its rain, had a mini-drought in the first two months of this year. Kind of hurts a lifelong resident like me to see the place turning brown. The rains are back now, though, so it will be back to having to beat back the jungle.

Aloha!

People

We would like to extend a welcome to Jeff Cabral, Observatory Technician who joined the JAC in October. Jeff will be working within the ETS Group where he will provide support for filling JAC instruments with liquid cryogens as scheduled daily. He will also perform general facilities maintenance tasks, vehicle safety checks and minor repairs, and transport equipment and supplies, including cryogens, to and from the summit facilities.