Newsletter

Seeing statistics at UKIRT in 2001

Figure 1: Seeing versus time of the night, point by point and in histogram form.

Michelle - the first five months

UKIRT's observatory statistics show that in its first 5 months of operations, Michelle was available for over 400 hours, of which 60% were observed, 1% were lost to faults and the rest lost to bad weather. These impressive figures are a fair reflection of the success that Michelle has enjoyed, with articles elsewhere in this issue illustrating the leap in performance at thermal infrared wavelengths that Michelle has brought to UKIRT.

All of Michelle's faculties have been used for successful PATT allocated programmes, from straightforward imaging to spectroscopy at low and high spectral resolutions, and even a little spectro-polarimetry. Of course there have been some problems. The four hours of lost time implied by the figures above hide a handful of runs that were lost due to either the cryostat front window becoming opaque because of water damage, or the recent (February 2002), loss of cooling power at the detector. The possibility of a recurrence of these problems is being eliminated as quickly as the busy observing schedule allows.

The details of Michelle's delivered performance are still being evaluated for publication in the next few months, but some basic conclusions are readily apparent.

Most importantly, although the sensitivities for imaging and spectroscopy are not far off the target of background limited performance, there are a number of factors which make some programmes rather more difficult to carry out than might be expected. For example, imaging through the 50% pass band filter at 10µm does not produce the anticipated sensitivity gain over the 10% pass band filters. This is due to a combination of the limited detector readout rate and the high sky background seen by the broad band filter. As a rough guide, in a 60 minute observation using the 50% pass band filter under typical seeing and sky conditions (Tau at 225 Ghz of 0.1), only 20 minutes will be spent collecting photons from the target, and a strong detection will only be achieved on sources brighter than 10mJy.

The planning applet on the JAC/Michelle web site will be modified to reflect the new sensitivity figures (please check the revision date at the top of the applet web page.)

Michelle is currently planned to be available on UKIRT until the end of September 2002. It will then have a new detector with improved cosmetic properties fitted, before being transferred to Gemini North where on-telescope commissioning is planned for January.

UKIRT has been testing the waters of flexible scheduling for the last two years, with a great deal of success. We undertook thsee experiments with the encouragement of the UKIRT Board in order to demonstrate that it is possible to take full advantage of good weather conditions for programmes that need them the most.

Our mini-flex experiments consisted of selecting two PATT projects and flexing between them in a block of time equal to the sum of their two "classical" allocations. The results are significant: Under the mini-flex conditions we have achieved completion rates of more than 90% for programmes which, if classically scheduled, would have achieved less than 20%.

In general this has worked best when scheduling a programme that has particular weather requirements along with one which has not. This has enabled us to flex programmes with seeing and telluric water vapour requirements. It is clearly also possible to flexibly schedule programmes requiring photometric weather, but to date we have not attempted this.

The release of ORAC (and in particular the ORAC-OT) at UKIRT has formalised observation preparation and has enabled us to contemplate the next step: providing software support to aid flexible scheduling. So far our mini-flex experiments were carried out "manually" - in fact what was being flexed was control of the observer's chair at the summit! The actual observing took place as it would have on a classical night.

If we are to extend the practice of flexible scheduling without increasing the load on the observer or UKIRT staff, we need software that will automate all stages of the process. Since our partner telescope, the JCMT, has been working towards this for some time under the guise of the OMP (the Obsevatory Management Project), we joined with them in order to produce a common software suite that will support flexible scheduling at UKIRT as well.

What does UKIRT look like in a potential OMP era? Quite similar to UKIRT in the ORAC era, in fact. PIs will be expected to gain PATT time and prepare their programmes with the ORAC-OT as they do now. There will be only two significant differences at this stage. Firstly, PIs will be expected to include a Site Quality Component in their projects. This will contain requirements on seeing, photometric conditions, tau and moon brightness. Secondly, observations in a submitted science programme are assumed schedulable at any time; if a PI wants two observations scheduled together (for example because one is a calibrator for the other) they have to group them together in what we call an MSB, a `Minimum Schedulable Block', which is the scheduling quantum if you like. A single observation is assumed to be an MSB of one; if that observation is a long integration that can be done on different nights, the PI can turn it into several MSBs of shorter duration, thus increasing its chances of being scheduled later in the night where a longer observation would not fit.

When a PI submits their science programme, much magic takes place. The OMP provides a sophisticated database server which takes the submitted program, splits it into its constituent MSBs and extracts information of a schedulable nature - not only the Site Quality information but also RAs, estimated duration, instrument configuration and so on. This information is stored in a relational database for efficient searching.

Currently at the telescope, the observer uses the ORAC-OM to retrieve a given PI's entire science programme, visually selects an observation from a list of names and sends it to the ORAC acquisition system for execution. Under the OMP, the observer will be able to use a `Query Tool' (the QT) to retrieve the most appropriate MSBs in any PI's programme. Criteria for the selection include whether the source is currently accessible, the weather conditions and the instrument availability. Although the list of MSBs will be sorted using an algorithm that folds the conditions with project properties such as TAG priority and completion status, the observer will be free to exercise their judgement and choose an MSB that is further down the list. They can also weed out certain instrument configurations - for example a novice observer with only imaging experience may wish to remove spectro-polarimetry MSBs from consideration.

Finally, we have learned from the JCMT experience that feedback to and from the PI about their programme is vital to the success of flexible scheduling because it increases scientific efficiency by encouraging the PI's involvement. So the OMP will provide a feedback system whereby the PI will be informed of the progress of their project, can retrieve their data, and can discuss any issues with observatory staff.

We note that the OMP does not enforce a strict queue scheduled operation. For example there is no requirement for a Phase II deadline, or for the entire time allocation to be requested at once, or for a single queue manager. The aim is to allow for the substantial gains of matching rare conditions to the projects best able to make use of them while retaining all the best features of classical scheduling: the ability to apportion your time as you choose, to change your observing strategy on the basis of early results and to have a support scientist who will help you make the most of your UKIRT time.

The OMP software was written by Tim Jenness, Matthew Rippa and Kynan Delorey at the JAC, and Martin Folger at the ATC. It will be commissioned on the UKIRT service programme in early March with the assistance of Paul Hirst. Following this and further tests in April, the UKIRT Board in May will discuss the details of the flexing process, observer selection, priority weighting, etc. Watch this space..!

UIST, the imager/spectrometer/IFU instrument designed to replace and augment the existing near-infrared instrumentation on UKIRT, has suffered a delay due to high read noise which became apparent when the science-grade Aladdin array was integrated into the cryostat late in 2001. Semester 02A was already scheduled by the time it became clear that a sizeable delay was inevitable. The UIST commissioning time which was scheduled for May through July was therefore removed, and the semester accordingly ends two weeks earlier than it otherwise would. As a result, Semester 02B will include approximately two weeks at the end of July.

Unfortunately, previously-planned JCMT heavy engineering through the summer imposes a further delay, whatever the progress of work on the read noise. This means that the earliest UIST can be brought to the JAC will be August 2002. Commissioning will follow and the instrument should be ready for shared-risks use in mid-December. UIST proposals are therefore invited for the end of Semester 02B.

Since this call for proposals is being made before the read noise has been reduced to acceptable levels, PIs should note in the Technical Case of the PATT form whether there are elements of your programme which could be addressed with CGS4, IRCAM or UFTI. This will generally not apply to IFU work or to programmes which require the long, simultaneous coverage offered by the HK grism, for example; but standard imaging and single-band spectroscopy can probably be accommodated to some extent by the existing instrumentation in the event we are unable to offer UIST.

Sidney Arakaki, Head of JAC Instrumentation Support, died suddenly in January 2002. Sidney was a key figure at the JAC, with more than two decades of experience - first on UKIRT, then also on the JCMT - and thus able to apply a huge amount of expertise in cryogenics, high vacuum and instrumentation. Sidney of course had many very close friends and colleagues both here at the JAC and at the UKATC in Edinburgh, and he will be greatly missed. While the professional and personal effects of his passing are perhaps not yet fully grasped, it is clear that we have lost a greatly valued colleague, a strong personality and a good friend.

It always amazes me...so much changes, yet so much stays the same. Here we are, another six months and a semester have gone by. Michelle is in action, going through the inevitable teething. UIST is delayed, somewhat messing up our nice scheduling for semester 02A, but not anything that cannot be dealt with.

The biggest change, though, is the loss of Sidney. I mean, it is one thing to hire and train someone to take his place, but it is also quite another thing entirely to replace his expertise, let alone his being. He is already sorely missed.

Sidney with his gasolene-powered blender at the Michelle Attitude Adjustment Party - the best Margaritas ever!

When I heard the news, I was totally flabbergasted. Sid was only four months younger than I, what could possibly have gone wrong?

When I walked into the first day on this job, 17 years ago, Sid was already here--and had been for a few years. After all these years, he was one of the very few left that had been here longer than I...

I was fortunate in that I was not on-shift when his funeral took place, but this was one of the darkest days I have had in years, as I ended up going to TWO funerals that day. It turned out my former Scoutmaster, college advisor and neighbor had passed away and ironically the services preceded Sid's by only a matter of hours. The last funeral I had been to was three years ago...the one before that, beyond rememberance. And, here I was, going to two in one day.

Thinking that this surely must be a sign of times to come for someone my age, it was with heavy heart that I left immediately and headed across town to Harrington's. I thought for sure that Sid would not have enjoyed what I went through one whit and that hoisting a few in his memory at one of his watering holes was surely what he would have appreciated.

I got there and there was nobody at all at the bar. Harrington's bar is quite small; there are only four barstools. I saw a Beck's dark sitting by the window, so I took the second stool in and ordered myself one of the same.

It was not too much later that a school teacher came in and asked if the seat was taken, and the bartender explained that the Beck's dark by the window was in honor of a good friend who's funeral had just taken place. Sid mostly stood there by the window, holding up the end of the bar. He wasn't one for much sitting.

A little later on quite a few of the gang, who had been at the services, drifted in. We hoisted a few in Sid's honor and enjoyed good repartee and comraderie; it seemed everyone had the same idea that this was most appropriate.

In fact, folks felt that this was not quite enough; another get-together took place a week later at Charley's in Kea'au, another of Sid's watering holes.

I think we all thought that Sid would have been pleased. He certainly would have been in the thick of it if he could have been there.

You have probably heard all the standard cliches...live every day, enjoy yourself, love life, love what you are doing in your work, etc., etc. I am sure Sid sure did.

So, that is the answer to my gloom. Thank you, Sid!

In the past 12 months UKIRT has seen a number of staff changes. In Issues 8 and 9 of the UKIRT Newsletter we bade a fond Aloha to Tim Hawarden and John Davies, who have both returned to the ATC in Edinburgh. To replace them we would now like to welcome Marc Seigar and Jane Buckle to the UKIRT team of Support Scientists.

Marc graduated from Liverpool John Moores University and arrived in Hilo via Post Doc. positions at Imperial College, London and the University of Ghent in Belgium. He works on galaxies of all shapes, flavours and forms, and has already contributed to the Newsletter! He is a regular on the soccer pitch (surprising, considering he's an Arsenal fan) and, from the look of his new car, seems to be settling in nicely to the Hawaiian lifestyle.

Jane came to us from UMIST where she recently obtained her Ph.D and completed a year as a Post Doc. Her research interests include disks, jets and outflows around young stars. Jane enjoys cycling and, to her credit, still hasn't bought a car. Surviving in Hilo without a car is like walking across the moon without your helmet on - challenging, to say the least! Happily, Marc says she can borrow his car anytime...

We are also delighted to welcome Brad Cavanagh to the JAC. Some regular visitors to Hilo may remember Brad, who was a Co-op student here a few years ago. Well, he must have had a good time because he's come back for more! Brad will be working on software support and development at UKIRT, and has already signed up for the next five years with the JAC soccer team (though he doesn't know it yet!).

The JAC also now has a Science Outreach Specialist, in the guise of Douglas Pierce-Price. Douglas, famous the world over for his work on the SCUBA map of the Galactic Centre (see the JCMT web pages for details), will be promoting the world-beating science routinely carried out with UKIRT and JCMT (by you lot!). So, if you have something astronomical to shout about, perhaps some results worthy of a press release, please send Douglas the details (d.pierce-price@jach.hawaii.edu)! When not promoting the JAC, Douglas will be continuing his research on the Galactic Centre and his work on data reduction algorythms.

We'd also like to welcome David Laird and John Pascual to the JAC. Dave brings with him much experience from his many years at the ATC in Edinburgh, where he worked on many of UKIRT's past and present instruments. While in Hawaii, Dave plans on taking up golf. For clubs, he's already invested in a set of Walmart's finest. John and his family lived on the Big Island before joining the JAC, so they will already know their Poi from their Portuguese sausage... John takes on the position of electronic/electrical engineer.

As many observers will know, Alistair Glasse is currently at the JAC on secondment from the ATC. Alistair is in Hilo commissioning Michelle on UKIRT (with Tom Kerr), and from the science already being achieved (see articles in this Newsletter), he's clearly been doing a great job! He expects to return to Edinburgh this summer, though probably it'll be too late to see Newcastle United come second in the English Premiership (behind Arsenal, quips Marc...).

Finally, Linsay Marcer, our finance officer, returned to PPARC in Swindon after 3 years in Hilo. She was replaced by Sally Nicol who (during working hours) will be keeping us all on the straight-and-narrow, financially speaking at least.

UNITED KINGDOM INFRARED TELESCOPE

Issue 10, Spring 2002