The Michelle Spectrometer arrives at UKIRT

Alistair Glasse

At long last, UKIRT has taken delivery of Michelle, the 8 to 25 -µmm, thermal infrared imager and spectrometer built at the UKATC in Edinburgh to replace the successful but aging spectrometer CGS3.

FIGURE 1: Michelle mounted on UKIRT

Figure 1 shows Michelle mounted on UKIRT; the silver pipes carry helium to the two closed cycle coolers which keep its 300kg of all-mirror optics below 24K and the Joule-Thomson valve which cools its detector to 5K. Michelle's total on-telescope weight is some 1.5 tonnes, a testament to UKIRT's continuing ability to adapt to the new generation of big, heavy instruments.

The cryostat is big for a reason. It holds both a dedicated imager and a long-slit spectrometer equipped with five diffraction gratings mounted on a rotating drum (behind the blue end cover in Figure 1). The observer will be able to switch from imaging to spectroscopy at spectral resolving powers ranging from one hundred to twenty thousand in a minute or two. A mechanism for selecting and rotating a half-waveplate is mounted just in front of the cryostat window, to provide Michelle with the additional capability of polarimetry for all imaging and spectroscopic paths.

FIGURE 2: Michelle spectrum of the Planetary nebula BD+30, taken during early commissioning at UKIRT.

The best way for a potential observer to get to grips with the wide range of spectral and spatial resolutions that can be selected for any observation is to either try out the Michelle component in version 3 of the ORAC Observing Tool, or to run the Observation Planning Applet, which can be found from links via the UKIRT instruments web page ( http://www.jach.hawaii.edu/UKIRT/instruments/).

As this article is being written, the instrument is in the early stages of on-telescope commissioning. The commissioning team is taking advantage of the sky's good transmission soon after sunrise to use bright standard stars as targets for the optimisation of Michelle's automated observing sequences.

However, a single night was allocated to Michelle on 22nd August, immediately after it had been mounted on the telescope. In spite of the fact that all data taking and instrument control was of necessity carried out using an engineering interface, the major functions of the instrument were all demonstrated successfully. Sub-arcsecond images of Vega were taken, with a signal strength consistent with the imager path and the detector achieving their nominal optical efficiency. The picture of Saturn on the front cover of this newsletter was produced late on that night by combining images taken at 10.3 (blue), 12.5 (green) and 18.5-µm (red). The difference in colours between the rings and the disk is tentatively ascribed to molecular emission bands around 12-µm in Saturn's atmosphere.

The spectrum included with this article (Figure 2) shows the first attempt to try out the low dispersion spectroscopy path by observing the bright planetary nebula BD+30 at a spectral resolving power of around 100. It shows the strong emission line of singly ionised neon at 12.8-µm as well as a broader emission feature at 11.3-µm due to dust.

The current plan for Michelle has it available for PATT scheduled observing until the summer of 2002, when it will be moved over to the Gemini telescope for commissioning and possibly the installation of a new detector with improved cosmetic properties.

ORACOT3

Andy Adamson

Oracot, the preparation tool for ORAC observing programmes, has been used successfully at UKIRT for more than two semesters. It was based on the Gemini observing tool, which was originally built with a commercial user-interface building tool which is now obsolete and unsupportable. The decision was taken to upgrade to a version of the OT using Swing, an industry-standard software library, for building its user interface.

FIGURE 1: Some components of the oracot3 preparation tool. (i) Top left: the master menu, from which li braries and the summit database are accessed. (ii) Bottom left: the science programme editor, wi th its integrated component editor, replaces the oracot2 separate programme and editor windows. (iii) Top right: the position editor (showing the Michelle science area, dichroic support and vi rtual guide telescope range). (iv) Middle (behind): the UKIRT template library, opened at UFTI, in a second science programme editor window.

Oracot3, as it is known, will be used from the point at which Michelle common-user observing commences in October 2001. A screen shot of some of the components is shown above. Some differences from the existing OT (oracot2) are immediately apparent.

• Firstly, it is now possible to run the OT without the external desktop; for use over the network from HP, this is good news.
• Secondly, the science programme editor and associated components (instrument, target etc.) are now contained in a single window, which simplifies keeping track of the various windows as one edits a science programme.
• Finally, the new OT has an improved position editor; this is based on Jsky and is easier to use, supports name resolution and suffers none of the memory problems to which the PE in oracot2 was prone.

Some testing remains to be done on the new system before it can be released to observers, but the benefits of the improved and standardized user interface are clearly apparent and we believe that it provides a more sensible route into the future than oracot. Oracot3 also understands XML, the language of the Observation Management Project, so it will fit naturally into the OMP when that is released later this year.

View from the top

Thor Wold

I was highly anticipating some hands-on experience to write about in this edition on both the mirror cooling system (described in the last Newsletter) and Michelle, but circumstances and the inevitable publishing deadline have intervened. As of this writing, both ought to be up and running very shortly, and I hope to have some news for our next edition.

With the advent of Michell observing, it is worthwhile to again remind observers that the JAC has an absolute rule of 14 hours above Hale Pohaku in any 24 hour period. What this means is a maximum of 13 hours at the telescope and one hour of transit time, up and back. The 13 hour mark is not meant to be an indicator of when to stop observations. What this means is that observers are expected to have wrapped up their observing, closed up shop and are out the door before the 13 hour limit has been reached. Not after. Our past experience with observing at thermal wavelengths has revealed this misconception, which simply will not be allowed to continue.

Improvements and changes continue with the road infrastructure in the Hilo area. For a city that has not seen any truely new roads since around 1970 (Komohana Street), we will soon have two new means of accessing Saddle Road from our Komohana Street office facility in University Park.

Completion of the Mohouli Street extension is set for around October. This will branch off uphill from the stoplight that is one block north of University Park on Komohana, and will meet up with Kaumana Drive (Saddle Road) at Curt's 76 service station, where we fill our JAC cars. This will eliminate having to traverse most of Komohana on your way up and down the mountain. Visitors over the past year may have noticed the construction.

Even better, the much-awaited (since the 1960s!) Puainako Street extension is now assured. Construction will start in the fall, with a completion target in 2003. This will jump off of Komohana Street about a block south of University Park and shoot all the way up to near the 7 mile mark on Kaumana Drive, very close to where it officially becomes Saddle Road, thereby avoiding nearly all of the winding bits of Kaumana.

The slated improvements to Saddle Road itself are currently mired in court over issues of hunting access, endangered species, and the re-routing of the roadbed up onto the slopes of Mauna Kea to avoid the military's Pohakuloa Training Area. The east side of Saddle Road is going to be the last part of the whole project, anyway, but I do hope this can get underway. The point is that the lower end of it will connect to the above-mentioned Puainako Street extension, which will make the whole process of going up and down the mountain so much more convenient and safe.

Much interest has been generated lately over a Mauna Kea silversword plant (Argyoxiphium sandwicense subsp. sandwicense) which is growing next to the gravel road on the way up to the summit (see the accompanying photograph). This is not to be confused with its cousin, the Haleakala silversword (Argyoxiphium sandwicense subsp. macrocephalum).

As this plant is rather robust and large, I wondered how it could kind of "spontaneously appear". Investigation has revealed that, indeed, it has not.

This is one of about 9 or 10 plants that were planted in that area about 9 years ago. The others were victimized by sheep and/or goats, so the remaining plant has had a fence erected around it. At this point, nobody seems to know who put up the fence, but it is certainly a good idea as these plants are very rare--one hopes this gives enough protection against the predators. Probably the reason this plant is being noticed is that the fencing is very apparent from the road, and the plant itself is getting big enough to be seen over the rocks. Its whiteness really glows against the volcanic background.

Efforts mandated by the Federal Government to fully eradicate the sheep population on Mauna Kea in order to protect endangered species have not been totally successful, as some animals still exist. Eradication efforts do continue, from time to time, to at least keep the population greatly diminished.

The State of Hawai'i and the Silversword Foundation have sponsored efforts for years to propagate silverswords, including the Mauna Kea subspecies, by collecting seeds and germinating them in the Hawai'i Volcanoes National Park in a greenhouse and then out-planting them in their native areas. This is no doubt how this particular plant got where it is.

There is an area that is fenced, over the shoulder of the mountain in a northerly direction from Hale Pohaku and at about 8000' elevation, that has a nice collection of these plants. However, getting to this area involves a two hour 4WD drive and a half-hour hike.

Silverswords seem to be ready to bloom after they produce polycarpic rosettes, kind of like branches. Indeed, the plant near the access road seems to be starting to bud, leading to speculation that it could possibly be getting ready to flower in a year or two. Silverswords live from about 9 to 20 years, dying after they flower. However, the mother plant only dies; the rosette offspring continue to grow. Flowering is generally mid-June to November.

This can lead to large agglomerations of the plants. In fact, it is reported that in the fenced area north of HP, one has so many rosettes that it resembles a bush about four feet across. This mother plant has produced a flower spike that is nearly 10 inches in diameter and 10 feet tall!

The flowers attract at least two known native pollinators; a yellow-faced bee and a type of fly (Nysisus terrestris). The flowers are about the size of an American quarter (about the size of a ten-pence-piece) and the flower spikes can contain as many as 600 florets.

While the silverswords have developed this dual method of ensuring survival and genetic diversity, they have evolved -- as did all native Hawaiian plants, in the absence of large grazing animals and man. Hawai'i is the world capital of extinct and endangered species. Many unique species of flora and fauna (mostly birds) have disappeared forever. This is not a title to be proud of! For a very nice photo gallery and further information, see: http://www.botany.hawaii.edu/faculty/carr/asan.htm

and click on Mauna Kea Silversword (or Haleakala silversword). There is also access from this page to the Silversword Alliance for even more information about the various species/subspecies.

We can only hope that man can intervene in time to save what is left of genetic diversity. That said, I do hope the fence works to keep the predators away...and that people will be mindful and not cause harm to this very rare plant. It just might be possible that in a short time, a flowering silversword might grace our drive to and from work.

John Davies

John Davies, support scientist of long standing, left the JAC in June to take up the position of Opticon scientist at the UKATC, organizing the UK's involvement in the Opticon initiative across Europe. John was responsible for the scheduling of UKIRT, and also supported visiting observers' use of the thermal-infrared spectrometer CGS3 up to its decommissioning in 1998. John's organizational ability was always well to the fore in dealing with scheduling requests from observers, some of which might be described as inventive. John took this in his stride, always emerged with an intact schedule, and satisfied observers where humanly possible (and sometimes where not).

It should not be forgotten that John was responsible for some scheduling innovations which have without doubt improved UKIRT's science output: reactive scheduling (enhancing the completion rate of the highest-rated science programmes) and more recently the flexing experiment (in which pairs of science programmes have been flexed together to take best advantage of variable observing conditions). Perhaps more remarkably, John carried out these duties while wearing some of the most distracting Hawaiian shirts ever seen on the University Park; these, too, will be missed and we wish John the very best in his new position.