Efficiency improvements – mainly by upgrade routes

A programme of sub-arcsecond astronomy

Provision of heterodyne focal plane arrays and associated correlator

Potential new (innovative and fast track) instruments

The telescope control system upgrade is a programme to improve the efficiency and capabilities for controlling telescope slewing, tracking and rastering. This project will replace the original VAX-based control system with a microprocessor and Unix-based system using the standard software environments of VxWorks and DRAMA that are in use at other observatories. The new system will have less latency and thus more efficiency, will be more flexible, and will be based on a modern, easy-to-maintain system. It is due for completion in the summer of 1999.

The OCS sits above the TCS and co-ordinates the movements of the telescope and secondary mirror with commands to the instruments to integrate, to the data storage system to write the data to disk, and so on. Once an observation has been completed, the data-file is automatically transferred to the Unix systems for analysis, and header information is uploaded to a Sybase observation database. Currently there are two separate systems, one for SCUBA and one for the heterodyne instruments. Again, both of these are VMS specific ADAM systems. The SCUBA OCS allows the parameters of an observation to be defined in advance in an Observation Definition File, and includes a simple queue manager. The heterodyne OCS requires each observation to be set up and executed interactively via a command line interface.

Both of these systems will be replaced by a new Java-based system known as the Todd (Telescope Observation Designer and Driver). This will allow JCMT software engineers and support scientists to set up "recipes" for each type of observation, including the ability to send commands in parallel to multiple sub-systems in an efficient manner. Parameters for the observation will be read from an observation definition file created in advance, and it will be possible to place a number of observations in a queue for automatic execution. The new OCS underwent proof-of-concept observing tests in November 1998; and should be completely installed in the summer of 1999.

At the centre of all work on new and upgraded heterodyne receivers is the development of new SIS mixers. The JCMT has a long-term contract with the Netherlands Space Research Organisation (SRON) at the University of Groningen for the production of SIS mixer devices. These devices are used for new receivers and for upgrades of existing receivers. SRON manufacture niobium devices covering the entire range of frequencies of interest to the JCMT, 200-900 GHz.

As one of the highest development priorities, the JCMT staff are working to improve the surface accuracy of the antenna in order to have better system sensitivity at the shortest wavelengths as well as cleaner beams. The goal is for an rms surface accuracy of ~22 microns through improved setting of the panels. Furthermore, through the use of active control system, this figure of merit will be achieved throughout the 16-hour observing window. To achieve these goals two sub-projects are underway.

Active Surface Control System: This is to implement a system where temperature measurements from the dish and backing structure are fed into an FEA model and used to predict corrective panel adjustments which will be made in real time. This project has required the development and validation of detailed thermal and mechanical FEA models of the dish and an upgrade to the panel adjuster control system. It is now almost complete, the final tests will be undertaken in the summer of 1999.

Provision of a new Holography Receiver: Because the determination of the surface accuracy is limited by the resolution capability of the current receiver, a new full-phase, dual-frequency (90, 180 GHz) holography system is being developed by MRAO, RAL and the JAC. This new receiver (RxH3) is in the final stages of construction and will be installed and commissioned in late summer. RxH3 should allow dish surface measurements to an accuracy of 5 microns or better.

These are in three phases: easy to achieve improvements in current system reliability and performance; more difficult and potential improvements in performance; potential provision of a new instrument with larger field-of-view and higher sensitivity. The first of these upgrades paths is planned for the summer of 1999 and will mainly involve installation of new and improved filters (from QMW) and replacement of the optics by mirrors with diamond turned surfaces (UKATC).

Design studies are underway to investigate the second phase, which includes potential provision of differential amplifiers to allow the ‘no-chop’ fast jiggling DREAM-like modes to be undertaken as well as the possibility of replacing the horns on the long wavelength array with more efficient designs.

A watching brief is being kept on detector development (for FIRST/Planck) with regard to the ultimate upgrade, or new instrument. Financial provision for these upgrades has been earmarked by the JCMT Board as an area of top-priority.

The JCMT will collaborate with the Smithsonian Sub-millimetre Array (SMA) in sub-millimetre aperture synthesis observations on Mauna Kea. The addition of the JCMT to the SMA increases the collecting area of the array by 60% and, in particular, enhances sensitivity on the longer baselines in the array. This will improve sensitivity to objects with small-scale structure such as compact protostellar regions and AGNs and may significantly improve important observing techniques such as self-calibration.

To collaborate with the SMA, we need to convert our receivers to 5GHz centre IFs, provide a polarisation rotator, install signal transmission fibres, and ensure the JCMT is controllable from the SMA. First light (fringes) for the SMA using two antennae on Mauna Kea are expected by the end of September 1999 and the JCMT should be in a position to participate fully in interferometry with the entire array in mid-2001. Earlier tests with the JCMT using our receivers in an overlap region of the Ifs is anticipated well before this time. The fibre optics cables have been purchased and a Memorandum of Understanding is expected to be agreed during 1999. The current mode of collaboration is based on the ‘altruistic principle’ of collaboration between astronomers on specific projects rather than a national/facility shares basis. Undoubtedly this will develop with observing experience.

Use of the enlarged array will bring two-fold benefits to users from the partner countries: access to sub-arcsecond submillimetre astronomy; experience of using an interferometer before the advent of the LMA.

In support of the existing JCMT-CSO short-baseline interferometry, water vapour radiometers have been developed by MRAO and are installed on both the JCMT and CSO. These instruments monitor changes in phase between the two telescopes induced by the atmosphere and provide a way to correct for this phase offset in real time or in post-time data reduction. The radiometer looks slightly offset from the main beam and we hope to use it to give a continuous record of the water vapour in the observing path and hence allow better extinction corrections. We are currently awaiting the software from MRAO before being able to commission this mode.

The ACSIS correlator is now well under way and the CDR is planned for June 2000 with delivery planned for late 2001. The prime contractor for ACSIS is HIA Penticton, with major work being undertaken by the UKATC and the JAC.

The Board recently approved the first of the focal plane heterodyne cameras. This is called HARP-B, and is a 345 GHz ("hence B-band") 16 element (4x4) camera. MRAO are the prime contractors with extensive work being also being carried out by the UKATC. The CoDR will be on March 22/23 and delivery is planned for mid-2002.

The camera is designed to suffer no significant performance penalty compared to the best single-beam systems. The receiver will be based on a horn-reflector antenna developed by Withington and others at MRAO; this has very low losses and naturally lends itself to a "stackable" linear layout.

Work is under way to formulate plans for the construction of an 8-element D-band (650 GHz) camera by the Netherlands. The funds for this camera are not yet approved.

There are no plans for an announcement of opportunity for instruments under this heading as yet. This will depend on how the D-band array and SCUBA upgrades progress. It is hoped that funds might be identified under this heading during the year 2000.

Although not strictly in this heading, provision of visitor instruments allowing collaborative astronomical programmes to be undertaken is ongoing. SPIFI, the South Pole Imaging Fabry-Perot Interferometer from Cornell, will be on the JCMT this April, and it is hoped this will become a long-term visitor instrument. Discussions are also underway with the MPIfR (Bonn) with regard to provision of an 800 GHz heterodyne receiver for collaborative programmes.

The JCMT has a tremendously exciting programme of developments, a number of which will come to fruition this summer. The future looks highly positive and productive. On the other hand, all is not sunshine and light. Operations continues to be extremely tightly squeezed by budgetary restrictions and in my opinion is now barely adequate for delivery of the mission to which we are committed and at the quality level we wish to achieve. I am aware of the dissatisfaction of users when we deliver less than 100% performance, and this is something that grates on every facility director.

However, there is only so much that I can do. The JCMT is a strictly resource-limited facility. I appeal to the users in the three countries to demonstrate and vocalise their support for the facility through their national peer review systems to put pressure on the agencies for additional operational funding for the JCMT which will bring benefit to all users.